Search

Raccoons ( Procyon lotor) are considered synanthropic, with high densities reported from urban landscapes. However, little information is available on population density and demography within the urban matrix. To better understand how urban land-use patterns influence raccoon density and demographic patterns, we sampled raccoons at multiple, replicated sites across an urban landscape. Density differed by land-use type ( F2,17 = 4.66, P = 0.027): urbanized sites, ${\bar {x}}$ = 4.96 ± 2.64 raccoons/km2, range = 1.25-10.00 raccoons/km2; urban open sites, ${\bar {x}}$ = 14.84 ± 6.35 raccoons/km2, range = 3.00-29.25 raccoons/km2; rural open sites, ${\bar {x}}$ = 15.50 ± 4.66 raccoons/km2, range = 13.00-20.25. Although we found no clear patterns in sex ratio, reproductive condition, or body condition, we observed differences in age structure among urban open, rural open, and urbanized sites. The most striking difference was the absence of older animals at urbanized sites and relatively low numbers of young individuals at urban open sites. Raccoons were the dominant mesocarnivore in open fragments, but less so in the urban matrix. Spatial variation in density across urban landscapes is likely influenced by site level differences in abundance of anthropogenic resources and differences in habitat quality. Furthermore, the association between changes in land-use and population age structure may have reflected different mortality sources across the landscape. Our results illustrate that wildlife species considered synanthropic may have complex relationships with urban landscapes. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Endogenous lipid pneumonia was found in 11 out of 15 (73.3%) opossums (Didelphis virginiana) captured in six municipalities from the state of Colima, Mexico. Macroscopically, multifocal yellow white subpleural plaques were found in the dorsocaudal region of both lungs. These lesions were extended to the pulmonary parenchyma. Microscopically, they were characterized by aggregates of macrophages in the alveolar walls and spaces. These macrophages had small lipid vacuoles in the cytoplasm. Also, hyperplasia of pneumocytes type II, perivascular lymphoid hyperplasia, emphysema and fibrosis were discovered. Based on these findings, endogenous lipid pneumonia was diagnosed, which seemed to be associated in 11 (73.3%) opossums with the presence of Didelphostrongylus hayesi in lungs. [ABSTRACT FROM AUTHOR]

The article presents case studies of four Virginia opossums (Didelphis virginiana) with severe clinical disease and inflammation associated with besnoitiosis. It says that symptoms include incoordination, circling, and sudden death. Besnoitia darlingi was confirmed in three of the four opossums through polymerase chain reaction (PCR) and sequencing.

Studies of limb bone loading in terrestrial mammals have typically found anteroposterior bending to be the primary loading regime, with torsion contributing minimally. However, previous studies have focused on large, cursorial eutherian species in which the limbs are held essentially upright. Recent in vivo strain data from the Virginia opossum (Dideiphis virginiana), a marsupial that uses a crouched rather than an upright limb posture, have indicated that its femur experiences appreciable torsion during locomotion as well as strong mediolateral bending. The elevated femoral torsion and strong mediolateral bending observed in D. virginiana might result from external forces such as a medial inclination of the ground reaction force (GRF), internal forces deriving from a crouched limb posture, or a combination of these factors. To evaluate the mechanism underlying the loading regime of opossum femora, we filmed D. virginiana running over a force platform, allowing us to measure the magnitude of the GRF and its three-dimensional orientation relative to the limb, facilitating estimates of limb bone stresses. This three-dimensional analysis also allows evaluations of muscular forces, particularly those of hip adductor muscles, in the appropriate anatomical plane to a greater degree than previous two-dimensional analyses. At peak GRF and stress magnitudes, the GRF is oriented nearly vertically, inducing a strong abductor moment at the hip that is countered by adductor muscles on the medial aspect of the femur that place this surface in compression and induce mediolateral bending, corroborating and explaining loading patterns that were identified in strain analyses. The crouched orientation of the femur during stance in opossums also contributes to levels of femoral torsion as high as those seen in many reptilian taxa. Femoral safety factors were as high as those of non-avian reptiles and greater than those of upright, cursorial mammals, primarily because the load magnitudes experienced by opossums are lower than those of most mammals. Thus, the evolutionary transition from crouched to upright posture in mammalian ancestors may have been accompanied by an increase in limb bone load magnitudes. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are an important class of posttranscriptional gene expression regulators. In the course of mapping novel marsupial-specific miRNAs in the genome of the gray short-tailed opossum, Monodelphis domestica, we encountered a cluster of 39 actual and potential miRNAs spanning 102 kb of the X chromosome. Analysis of the cluster revealed that 37 of the 39 miRNAs are predicted to form thermodynamically stable hairpins, and at least 3 members have been directly cloned from M. domestica tissues. The sequence characteristics of these miRNAs suggest that they all descended from a single common ancestor. Further, 2 distinct families appear to have diversified from the ancestral sequence through different duplication mechanisms: one through a series of simple tandem duplications and the other through a recurrent transposon-mediated duplication process. [ABSTRACT FROM PUBLISHER]

Terrestrial locomotion can impose substantial loads on vertebrate limbs. Previous studies have shown that limb bones from cursorial species of eutherian mammals experience high bending loads with minimal torsion, whereas the limb bones of non- avian reptiles (and amphibians) exhibit considerable torsion in addition to bending. It has been hypothesized that these differences in loading regime are related to the difference in limb posture between upright mammals and sprawling reptiles, and that the loading patterns observed in non-avian reptiles may be ancestral for tetrapod vertebrates. To evaluate whether non- cursorial mammals show loading patterns more similar to those of sprawling lineages, we measured in vivo strains in the femur during terrestrial locomotion of the Virginia opossum (Dideiphis virginiana), a marsupial that uses more crouched limb posture than most mammals from which bone strains have been recorded, and which belongs to a dade phylogenetically between reptiles and the eutherian mammals studied previously. The presence of substantial torsion in the femur of opossums, similar to non- avian reptiles, would suggest that this loading regime likely reflects an ancestral condition for tetrapod limb bone design. Strain recordings indicate the presence of both bending and appreciable torsion (shear strain: 419.1±212.8μϵ) in the opossum femur, with planar strain analyses showing neutral axis orientations that placed the lateral aspect of the femur in tension at the time of peak strains. Such mediolateral bending was unexpected for a mammal running with near-parasagittal limb kinematics. Shear strains were similar in magnitude to peak compressive axial strains, with opossum femora experiencing similar bending loads but higher levels of torsion compared with most previously studied mammals. Analyses of peak femoral strains led to estimated safety factor ranges of 5.1-7.2 in bending and 5.5-7.3 in torsion, somewhat higher than typical mammalian values for bending, but approaching typical reptilian values for shear. Loading patterns of opossum limb bones therefore appear intermediate in some respects between those of eutherian mammals and non-avian reptiles, providing further support for hypotheses that high torsion and elevated limb bone safety factors may represent persistent ancestral conditions in the evolution of tetrapod limb bone loading and design. [ABSTRACT FROM AUTHOR]

The article discusses research which examines the chromosomal instability and growth inhibition of cultured marsupial (opossum) cells following DNA polymerase α inhibitor treatment. The study showed that dehydroaltenusin inhibits euthorian and metatherian DNA replication. Further, it revealed that dehyroaltenusin clearly suppressed the growth of metatherian cultured cells.

The article offers new data regarding the natural history and morphometrics of Lutreolina crassicaudata, noted to be one of the least studied didelphid marsupial species, in Argentina. Field work was performed in the central-eastern part of the country during two consecutive years and juveniles and sub-adults were caught during summer and autumn. Reproduction revealed seasonality with a continuous breeding period from spring to summer and the analysis of 17 scats which belong to 17 individuals depicted mainly seeds and vegetal remains, as well as amphibians, birds and invertebrates.

The article discusses non-traditional models in understanding mechanisms that regulate limb development among mammals. Research in non-traditional mammals have been done on organisms including opossum Monodelphis domestica, bats Carollia perspicillata, and pigs Sus scrofa, to understand the modified evolution of their limb development, as well as generate adult morphologies. Knowledge of differing limb development among mammals will improve understanding of human development.

In Brazil there is not report of Salmonella in opossum, so then, the objective of this study is to determine the isolation frequency of Salmonella enterica in opossum in São Paulo State, Brazil. From January 2005 to December 2006, 106 D. aurita and 40 D. albiventris were necropsied and samples from small and large intestine and cloacal swab were collected. These samples were submitted to direct plating in Mac Conkey agar and parallel suspension in Rappaport- Vassiliadis and Tetrationate broths with posterior streaking in XLT4 agar. The characterization of the isolates was done through biochemical tests and serotyping. Salmonella enterica was found in 17.0% (18/106) of the D. aurita; 50% presented the bacteria in the small intestine (SI), 88.9% in the large intestine (LI) and 66.7% in the cloaca. Of the S. enterica were found the subspecies: diarizonae (11.1%), enterica and houtenae (5.5% each); and the serotypes of the S. enterica enterica were Newport (83.3%), Typhimurium and Cerro (5.5% each). In the D. albiventris 17.5% (7/40) were positive; 42.8% in the SI, 85.7% in the LI and 71.4% in the cloaca. Newport (71.4%) was also the most frequent serotype and the second were Typhimurium, Bareilly and Thompson (14.3% each). The presence of Salmonella enterica in the intestines of opossums in Brazil was proved. [ABSTRACT FROM AUTHOR]

Abstract: Changes in gene expression have been measured 24h after injury to mammalian spinal cords that can and cannot regenerate. In opossums there is a critical period of development when regeneration stops being possible: at 9days postnatal cervical spinal cords regenerate, at 12days they do not. By the use of marsupial cDNA microarrays, we detected 158 genes that respond differentially to injury at the two ages critical for regeneration. For selected candidates additional measurements were made by real-time PCR and sites of their expression were shown by immunostaining. Candidate genes have been classified so as to select those that promote or prevent regeneration. Up-regulated by injury at 8days and/or down-regulated by injury at 13days were genes known to promote growth, such as Mitogen-activated protein kinase kinase 1 or transcription factor TCF7L2. By contrast, at 13days, up-regulation occurred of inhibitory molecules, including annexins, ephrins, and genes related to apoptosis and neurodegenerative diseases. Certain genes such as calmodulin 1 and NOGO, changed expression similarly in animals that could and could not regenerate without any additional changes in response to injury. These findings confirmed and extended changes of gene expression found in earlier screens on 9 and 12day preparations without lesions and provide a comprehensive list of genes that serve as a basis for testing how identified molecules, singly or in combination, promote and prevent central nervous system regeneration. [Copyright &y& Elsevier]

Abstract: Gnathostoma turgidum is a gastric nematode parasite of opossums found in the Americas. We recently found that G. turgidum juveniles appear in the liver of the opossums where they become mature adults and almost synchronously move to the stomach during certain months of the year, suggesting the importance of the liver for the growth and maturation of this species in the final hosts. In this study we attempted to detect G. turgidum larvae in the liver of opossums, Didelphis virginiana that are the natural final hosts. The results show that tiny (<3mm in length) third stage larvae (L3) appeared in the liver of opossums around November and December. Also in the liver, we found large L3 of up to about 10mm in length together with juveniles and mature adults from February to March. In spite of their length, large L3 have 4 rows of hooklets, and their gonads remained undeveloped. Morphological features of the small and large L3 of G. turgidum are described including scanning electron microscope images. The seasonal switching of the several growth stages of G. turgidum from small L3 to adult worms in the liver and eventual migration to the stomach in opossums suggests the unique feature of G. turgidum utilizing the liver as the maturation site. [ABSTRACT FROM AUTHOR]

Abstract: The B cell receptor (BCR) is a multiprotein complex that is pivotal to antigen recognition and signal transduction in B cells. It consists of an antigen binding component, membrane Ig (mIg), non-covalently associated with the signaling component, a disulphide-linked heterodimer of CD79a and CD79b. In this study, the gene and corresponding cDNA for CD79a and CD79b in the gray short-tailed opossum, as well as the cDNA sequences for CD79a and CD79b in the tammar wallaby, are described. Many of the structural and functional features of CD79a and CD79b were conserved in both marsupials, including the ITAM regulatory motif in the cytoplasmic tails of both subunits. The marsupial CD79 sequences shared a high degree of amino acid identities of 76% (CD79a) and 72% (CD79b) to each other, as well as 60–61% (CD79a) and 58–59% (CD79b) with their eutherian counterparts. RT-PCR analysis of CD79a and CD79b transcripts in the immune tissues of tammar pouch young revealed CD79a transcripts in the bone marrow, cervical thymus and spleen at day 10 postpartum. CD79b transcripts were detected in the bone marrow and cervical thymus at day 10 but were not detected in the spleen until day 21 postpartum. These results suggest that a functional BCR may not be assembled until day 21 postpartum and the tammar neonate may not be capable of mounting an effective adaptive immune response until this time. The molecular information presented here will allow further investigation of the role of the CD79 subunits in marsupial B cell signaling, especially during ontogeny and disease. [Copyright &y& Elsevier]

Passive treatment of raccoons (Procyon lotor) through distribution of vaccine-laden baits recently has emerged as a potential solution to address health and economic conflicts associated with raccoon rabies and may have applications in the management of other pathogens carried by raccoons if frequent bait deployments are used. Consumption of baits by nontarget species reduces the efficiency in which baits can be used to manage wildlife disease, although no study has explicitly evaluated the influence of bait competitor density on the ability to treat raccoons. Our objectives were to use the biomarker Rhodamine B (RB) to 1) evaluate patterns of raccoon bait acceptance as a function of competition with Virginia opossums (Didelphis virginiana), the dominant bait competitor; 2) characterize attributes of opossum bait acceptance to improve efficiency of raccoon treatment; and 3) evaluate the effect of repeated bait exposure on rates of bait acceptance as may be required in the management of wildlife disease issues beyond rabies. Identifying bait consumption by individuals based on the presence of an RB mark in a sample of whiskers, we used logistic regression to model raccoon and opossum bait acceptance as a function of bait availability, previous exposure to baits, demographic attributes, and an index of time spent in the baited area (residency index). For both raccoons and opossums, the best measure of bait availability was the variable number of baits per opossum. The most parsimonious logistic regression model for raccoon bait acceptance included the variables baits per opossum, exposure history, and residency index. The strength of the variable baits per opossum relative to competing measures of bait availability indicated bait consumption by opossums significantly limited the ability to treat raccoons. The most parsimonious model for opossum acceptance was composed of the variables baits per opossum, sex, weight, residency index, baits per opossum × sex, and weight × sex. Patterns of opossum bait acceptance likely were driven by effects of bait availability and sex-dependent differences in movement. Our results call attention to the importance of bait competition in limiting the ability to effectively treat raccoon populations through distribution of baits and suggest managers incorporate information on density of bait competitors, particularly opossums, in allocation of baits. [ABSTRACT FROM AUTHOR]

Abstract: The effects of perinatal exposure to progesterone (P) and estradiol (E) on sexual differentiation of behavior and morphology were examined by treating male and female gray short-tailed opossums on postnatal day 8 with progesterone alone (P), P plus estradiol (E) (PE), the P receptor antagonist mifepristone/RU486 (MIF), or corn oil control (C) and gonadectomizing them before puberty. When given female hormone replacement therapy in adulthood and tested with intact stimulus males, MIF animals showed less female-typical aggressive threat behavior than animals in other treatment groups. Stimulus males scent marked in more tests involving females than males and in more tests involving MIF animals than animals in other treatment groups. Body weight was lower in females than in males and was lower in MIF animals than in animals in other treatment groups, and P females failed to show female-typical genital locks after copulation. Sexual receptivity was similar in males and females and, while not decreased by any perinatal hormone treatment, was higher in PE males than in animals of either sex in any treatment group. These findings suggest that perinatal exposure to P is associated with the organization of feminine threat behavior and the defeminization of attractivity, body weight and genital anatomy in this marsupial. Reasons for these findings and for why female sexual receptivity is enhanced by perinatal exposure to exogenous E only in an endogenous masculine environment are discussed. [ABSTRACT FROM AUTHOR]

NKG2D is a major activating receptor of natural killer cells. Its ligands are major histocompatibility complex (MHC) class I-like molecules whose expression is induced by cellular stresses such as infections and tumorigenesis. Humans have two families of NKG2D ligands (NKG2DL): MHC class I-related chains (MIC) encoded in the MHC and UL16-binding proteins (ULBP) encoded outside the MHC. By contrast, mice have only the latter family of ligands; instead, they have non-MHC-encoded MILL molecules that are closely related to MIC, but do not function as NKG2DL. To gain insights into the origin and evolution of MIC, ULBP, and MILL gene families, we conducted comparative genomic analysis of NKG2DL family genes in five mammalian species. In the opossum MHC, we identified a ULBP-like gene adjacent to a previously described MIC-like gene, suggesting that ULBP genes were originally encoded in the MHC. The opossum genome also contained a transcribed MILL-like gene in a region syntenic to the rodent regions encoding MILL molecules. These observations indicate that MIC-, ULBP-, and MILL-like genes emerged before the divergence of placental and marsupial mammals. Comparison of the human, cattle, rat, mouse, and opossum genomes indicates that after emigration from the MHC, ULBP genes underwent extensive duplications in each species. In mice, some of the ULBP genes appear to have been translocated telomerically on the same chromosome, forming a major cluster of existent NKG2DL genes. [ABSTRACT FROM AUTHOR]

Mammalian ALDH3 isozymes participate in peroxidic and fatty aldehyde metabolism, and in anterior eye tissue UV-filtration. BLAT analyses were undertaken of the opossum genome using rat ALDH3A1, ALDH3A2, ALDH3B1, and ALDH3B2 amino acid sequences. Two predicted opossum ALDH3A1-like genes and an ALDH3A2-like gene were observed on chromosome 2, as well as an ALDH3B-like gene, which showed similar intron–exon boundaries with other mammalian ALDH3-like genes. Opossum ALDH3 subunit sequences and structures were highly conserved, including residues previously shown to be involved in catalysis and coenzyme binding for rat ALDH3A1. Eleven glycine residues were conserved for all of the opossum ALDH3-like sequences examined, including two glycine residues previously located within the stem of the rat ALDH3A1 active site funnel. Phylogeny studies of human, rat, opossum, and chicken ALDH3-like sequences indicated that the common ancestor for ALDH3A- and ALDH3B-like genes predates the appearance of birds during vertebrate evolution. [ABSTRACT FROM AUTHOR]

Opossum is considered one of the most primitive mammals, with transition evolutive characteristics. In mammals, the aorta artery is referred as the main body blood vessel. The arteries wall structural organization follows a basic pattern, being contituted of three tunics: Intima, Median and Adventicial. After euthanasia, three samples of opossum had segments from the aorta artery ascendent, thoracic descending and abdominal descending portions removed, fixed in phormalin at 10% for 48 hours. Then, the material was washed in alcohol 70% several times, dehydrated in alcohois of growing concentrations, diafanized in xylol and included in "paraplast". Cuts with 5 to 7μm of thickness were placed in histological laminae and submitted to color methods of Hematoxilin-Eosin, Masson, Mallory and Calleja Tricromics. It was observed that in the different portions ascendent, thoracic and abdominal descending of aorta, the intima tunic presents much thick, made up of a layer of smooth muscular cells and elastic fibers, forming a limiting internal elastic membrane. In the three portions studied, the median tunic was the most evident layer, constituted of colagen fibers, smooth muscular cells arranged in a circular manner and elastic fibers, showing a variation in the mural elements proportion. It was evidenced the presence of a external elastic lamina, marking the transition between the median and adventicial tunic, formed by elastic fibers condensation. The aortic adventicial tunic showed to be little organized, having in its structure predominantely colagen fibers beans with some isolated smooth muscular fibers or in small fascicules among a few elastic fibers. [ABSTRACT FROM AUTHOR]

We use opossums Monodelphis domestica to study the development of mammalian motor systems. The immature forelimbs of the newborn perform rhythmic and alternating movements that are likely under spinal control. The hindlimbs start moving in the second week. Chemical synapses are scant in the spinal enlargements of neonatal opossums and the presence of electrochemical synapses has not been evaluated in this species or in other marsupials. As a first step aiming at evaluating the existence of such synapses in the neonatal spinal cord, we have investigated the presence of the exclusively neuronal gap junction protein connexin36 (Cx36) by immunohistochemistry in light microscopy. At birth, Cx36 immunoreactivity is moderate in the presumptive gray matter in both enlargements. Thereafter, it decreases gradually, except in the superficial dorsal horn where it increases to a plateau between P10 and P20. Cx36 labeling is detected in the presumptive white matter at birth, but then decreases except in the dorsal part of the lateral funiculus, where it is dense between P10 and P20. Cx36 has become virtually undetectable by P52. The presence of Cx36 in the spinal enlargements of postnatal opossums suggests that neurons might be linked by gap junctions at a time when chemical synapses are only beginning to form. The greater abundance of Cx36 observed transiently in the superficial dorsal horn suggests a stronger involvement of this protein in spinal sensory systems than in direct motor control of the limbs. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

BLAT (BLAST-Like Alignment Tool) analyses of the opossum (Monodelphis domestica) and zebrafish (Danio rerio) genomes were undertaken using amino acid sequences of the acylglycerol acyltransferase (AGAT) superfamily. Evidence is reported for 8 opossum monoacylglycerol acyltransferase-like (MGAT) (E.C. 2.3.1.22) and diacylglycerol acyltransferase-like (DGAT) (E.C. 2.3.1.20) genes and proteins, including DGAT1, DGAT2, DGAT2L6 (DGAT2-like protein 6), AWAT1 (acyl CoA wax alcohol acyltransferase 1), AWAT2, MGAT1, MGAT2 and MGAT3. Three of these genes (AWAT1, AWAT2 and DGAT2L6) are closely localized on the opossum X chromosome. Evidence is also reported for six zebrafish MGAT- and DGAT-like genes, including two DGAT1-like genes, as well as DGAT2-, MGAT1-, MGAT2- and MGAT3-like genes and proteins. Predicted primary, secondary and transmembrane structures for the opossum and zebrafish MGAT-, AWAT- and DGAT-like subunits and the intron–exon boundaries for genes encoding these enzymes showed a high degree of similarity with other members of the AGAT superfamily, which play major roles in triacylglyceride (DGAT), diacylglyceride (MGAT) and wax ester (AWAT) biosynthesis. Alignments of predicted opossum, zebrafish and other vertebrate DGAT1, DGAT2, other DGAT2-like and MGAT-like amino acid sequences with known human and mouse enzymes demonstrated conservation of residues which are likely to play key roles in catalysis, lipid binding or in maintaining structure. Phylogeny studies of the human, mouse, opossum, zebrafish and pufferfish MGAT- and DGAT-like enzymes indicated that the common ancestors for these genes predated the appearance of bony fish during vertebrate evolution whereas the AWAT- and DGAT2L6-like genes may have appeared more recently prior to the appearance of marsupial and eutherian mammals. [Copyright &y& Elsevier]

Abstract: Sarcocystis neurona, a protozoal parasite shed by opossums (Didelphis virginiana), has been shown to cause significant morbidity and mortality in horses, sea otters, and other marine mammals. Over the course of 3 years (fall 2005–summer 2008), opossums from central California were tested for infection with S. neurona. Of 288 opossums sampled, 17 (5.9%) were infected with S. neurona based on the molecular characterization of sporocysts from intestinal scrapings or feces. Risk factors evaluated for association with S. neurona infection in opossums included: age, sex, location, season, presence of pouch young in females, concomitant infection, and sampling method (live-trapped or traffic-killed). Multivariate logistic regression analysis identified that opossums in the Central Valley were 9 times more likely to be infected than those near the coast (p =0.009). Similarly, opossum infection was 5 times more likely to be detected during the reproductive season (March–July; p =0.013). This first investigation of S. neurona infection prevalence and associated risk factors in opossums in the western United States can be used to develop management strategies aimed at reducing the incidence of S. neurona infections in susceptible hosts, including horses and threatened California sea otters (Enhydra lutris neries). [Copyright &y& Elsevier]

Abstract: Trypanosoma cruzi is a genetically and biologically diverse species. In the current study we determined T. cruzi infection dynamics in two common North American reservoirs, Virginia opossums (Didelphis virginiana) and raccoons (Procyon lotor). Based on previous molecular and culture data from naturally-exposed animals, we hypothesised that raccoons would have a longer patent period than opossums, and raccoons would be competent reservoirs for both genotypes T. cruzi I (TcI) and TcIIa, while opossums would only serve as hosts for TcI. Individuals (n =2 or 3) of each species were inoculated with 1×106 culture-derived T. cruzi trypomastigotes of TcIIa (North American (NA) – raccoon), TcI (NA – opossum), TcIIb (South American – human), or both TcI and TcIIa. Parasitemias in opossums gradually increased and declined rapidly, whereas parasitemias peaked sooner in raccoons and they maintained relatively high parasitemia for 5weeks. Raccoons became infected with all three T. cruzi strains, while opossums only became infected with TcI and TcIIb. Although opossums were susceptible to TcIIb, infection dynamics were dramatically different compared with TcI. Opossums inoculated with TcIIb seroconverted, but parasitemia duration was short and only detectable by PCR. In addition, raccoons seroconverted sooner (3–7days post inoculation) than opossums (10days post inoculation). These data suggest that infection dynamics of various T. cruzi strains can differ considerably in different wildlife hosts. [Copyright &y& Elsevier]

Evidence is presented for six opossum ALDH1A genes, including four ALDH1A1-like genes on chromosome 6 and ALDH1A2- and ALDH1A3-like genes on chromosome 1. Predicted structures for the opossum aldehyde dehydrogenase (ALDH) subunits and the intron–exon boundaries for opossum ALDH genes showed a high degree of similarity with other mammalian ALDHs. Phylogenetic analyses supported the proposed designation of these opossum class 1 ALDHs as ALDH1A-like, ALDH1A2-like, and ALDH1A3-like and are therefore likely to play important roles in retinal and peroxidic aldehyde metabolism. Alignments of predicted opossum ALDH1A amino acid sequences with sheep ALDH1A1 and rat ALDH1A2 sequences demonstrated conservation of key residues previously shown to participate in catalysis and coenzyme binding. Amino acid substitution rates observed for family 1A ALDHs during vertebrate evolution indicated that ALDH1A2-like genes are evolving slower than ALDH1A1- and ALDH1A3-like genes. It is proposed that the common ancestor for ALDH1A genes predates the appearance of birds during vertebrate evolution. [ABSTRACT FROM AUTHOR]

Abstract: Computational methods were used to predict the amino acid sequences and gene locations for mammalian lactate dehydrogenase (LDH) genes and proteins using genome sequence databanks. Human LDHA, LDHC and LDH6A genes were located in tandem on chromosome 11, while LDH6B and LDH6C genes were on chromosomes 15 and 12, respectively. Opossum LDHC and LDH6B genes were located in tandem with the opossum LDHA gene on chromosome 5 and contained 7 (LDHA and LDHC) or 8 (LDH6B) exons. An amino acid sequence prediction for the opossum LDH6B subunit gave an extended N-terminal sequence, similar to the human and mouse LDH6B sequences, which may support the export of this enzyme into mitochondria. The platypus genome contained at least 3 LDH genes encoding LDHA, LDHB and LDH6B subunits. Phylogenetic studies and sequence analyses indicated that LDHA, LDHB and LDH6B genes are present in all mammalian genomes examined, including a monotreme species (platypus), whereas the LDHC gene may have arisen more recently in marsupial mammals. [Copyright &y& Elsevier]

Abstract: CD5 has previously been identified in marsupial tissues using anti-human CD5. However, despite the known cross-reactivity of the antibody in marsupial tissues, the cDNA sequence has not previously been characterised in any marsupial. This study has identified the CD5 gene in the opossum genome database and has characterised the CD5 cDNA sequence from the tammar wallaby. Both marsupial CD5 sequences have a high level of sequence identity to known eutherian CD5 sequences, are cysteine-rich and have identical structural motifs to their eutherian homologs. CD5 transcripts were strongly expressed in adult tammar wallaby spleen, mammary node and blood, and expressed at a lower level in liver, kidney and heart tissues. Characterisation of CD5 in marsupials allowed a comparison to the epitope sequence of anti-human CD5 and showed a high level of sequence identity. [Copyright &y& Elsevier]

Abstract: In eutherian mammals, CD8 is a key receptor of cytotoxic T cells and plays a pivotal role in the recognition and elimination of infected host cells by cell-mediated cytotoxicity. Here, we report the molecular cloning and expression analysis of CD8α and CD8β cDNAs in two marsupial species, the gray short-tailed opossum and the tammar wallaby. The opossum and tammar CD8 sequences share a high degree of amino acid identity of 63% (CD8α) and 57% (CD8β) to each other as well as 36–45% (CD8α) and 38–41% (CD8β) with their eutherian counterparts. In addition, many of the signature features of eutherian CD8α and CD8β are preserved in both marsupials including the two invariant cysteines that form the intra-chain disulphide bond in the extracellular IgSfV domain and the two hinge region cysteines involved in dimerisation between the two subunits. The p56 lck binding motif in the cytoplasmic tail of the CD8α subunit is also conserved. Interestingly, the opossum CD8α and the tammar CD8β sequences have a truncated cytoplasmic tail. RT-PCR analysis of CD8α and CD8β transcripts in the tissues of the adult opossum and tammar showed broad tissue expression with a high level of expression observed in the lymphoid tissues of both marsupials. Furthermore, RT-PCR analysis of CD8α and CD8β transcripts in the immune tissues of tammar young over the first 120 days of pouch life revealed a pattern of expression analogous to the maturation of the lymphoid tissues. This is the first report confirming the presence of CD8 in the tissues of a marsupial and will provide the tools to further analyse T cell subsets in this unique group of mammals. [Copyright &y& Elsevier]

Abstract: BLAT (BLAST-Like Alignment Tool) analyses and interrogations of the recently published opossum genome were undertaken using previously reported rat ADH amino acid sequences. Evidence is presented for six opossum ADH genes localized on chromosome 5 and organized in a comparable ADH gene cluster to that reported for human and rat ADH genes. The predicted amino acid sequences and secondary structures for the opossum ADH subunits and the intron–exon boundaries for opossum ADH genes showed a high degree of similarity with other mammalian ADHs, and four opossum ADH classes were identified, namely ADH1, ADH3, ADH6 and ADH4 (for which three genes were observed: ADH4A, ADH4B and ADH4C). Previous biochemical analyses of opossum ADHs have reported the tissue distribution and properties for these enzymes: ADH1, the major liver enzyme; ADH3, widely distributed in opossum tissues with similar kinetic properties to mammalian class 3 ADHs; and ADH4, for which several forms were localized in extrahepatic tissues, especially in the digestive system and in the eye. These ADHs are likely to perform similar functions to those reported for other mammalian ADHs in the metabolism of ingested and endogenous alcohols and aldehydes. Phylogenetic analyses examined opossum, human, rat, chicken and cod ADHs, and supported the proposed designation of opossum ADHs as class I (ADH1), class III (ADH3), class IV (ADH4A, ADH4B and ADH4C) and class VI (ADH6). Percentage substitution rates were examined for ADHs during vertebrate evolution which indicated that ADH3 is evolving at a much slower rate to that of the other ADH classes. [Copyright &y& Elsevier]

Abstract: Progesterone receptor immunoreactivity (PRir) in brain areas involved in reproductive behavior in eutherian species was examined for the first time in a female marsupial, the gray short-tailed opossum (Monodelphis domestica, hereinafter, opossum). PRir in nuclei of neurons, measured as area covered by stained nuclei, was seen in the arcuate nucleus (Arc); anteroventral periventricular nucleus (AVPv); bed nucleus of the stria terminalis (BST); medial preoptic area (MPOA), and ventromedial hypothalamus (VMH), but not in control areas adjacent to the hypothalamus or cortex. Female opossums are induced into cytological, urogenital sinus (UGS), estrus by male pheromones and into behavioral estrus, i.e., receptivity, by pairing with a male, and both estradiol (E) and progesterone (P) are involved in induction of receptivity in intact and ovariectomized females. PRir in the AVPv, MPOA, and VMH was very low in females that had never been exposed to males or their scent marks, i.e., naïve anestrous (NVA) females, and either previous or current exposure to males or their scent marks was associated with elevated PRir. PRir was significantly higher in the AVPv and MPOA of anestrous females with previous but no current exposure to males and their scent marks, i.e., experienced anestrous (EXPA) females, than in NVA females, but PRir was significantly lower in the MPOA and VMH of EXPA females than in females that were behaviorally receptive and had recently copulated, i.e., behavioral receptive estrous (BRE) females. PRir was higher in the VMH of both UGS estrous (UGSE) and BRE females compared to that in EXPA animals, but PRir did not differ between UGSE and BRE females in any of the 3 brain areas examined, including the MPOA These results provide evidence that pheromonal induction of estrus and sexual receptivity in opossums is associated with elevation of PRir in the VMH and MPOA and that prior exposure to males or their pheromones, even in the absence of current male stimuli, is associated with persistent elevation of PRir in the AVPv and MPOA. [Copyright &y& Elsevier]

Earlier studies have revealed the ability of sera from several mammals to neutralize the toxic effects of snake venom. The Venezuelan opossum (Didelphis marsupialis) is one that has been found to inhibit hemorrhagic and proteolytic activities of venoms from many species of snakes. In this article it is shown that the opossum sera and its 0.15DM fraction were able to completely neutralize both hemorrhagic and hydrolysis (proteolysis) of casein effects induced by venom of the Lansberg's hognose pit viper (Porthidium lansbergii hutmanni). We have used DEAE-cellulose ion exchange chromatography to collect protein fractions from D. marsupialis sera which were able to defend mice from the lethal effects of P.l. hutmanni venom. The fractions separated were homogeneous by conventional electrophoresis using SDS-PAGE. The protein bands obtained contained molecular weights of ∼ 6 to 220 kDa. These results revealed the presence of proteases inhibitors in the opossum sera fractions and the inhibition of venom activity by opossum sera suggesting a reciprocal adaptation at the molecular level. [ABSTRACT FROM AUTHOR]

Abstract: Quadrupedal animals moving on arboreal substrates face unique challenges to maintain stability. The torque generated by the limbs around the long axis of a branch during locomotion may clarify how the animals remain stable on arboreal supports. We sought to determine what strategy gray short-tailed opossums (Monodelphis domestica) use to exert torque and avoid toppling. The opossums moved across a branch trackway about half the diameter of their bodies. Part of the trackway was instrumented to measure substrate reaction forces and torque around the long axis of the branch. Kinematic analysis was used to estimate the center of pressure of the manus and pes; from center of pressure and vertical and mediolateral forces, the torque generated by substrate reaction forces versus muscular effort could be determined. Forelimbs generated significantly greater torque than hindlimbs, which is probably explained by the greater weight-bearing role of the forelimbs. Fore- and hindlimbs generated torque in opposite directions because contralateral fore- and hindlimbs typically contacted the branch. Torque generated by muscular effort, however, was often in the same direction in both fore- and hindlimbs. The muscle-generated torque is likely the result of mediolateral movement of the center of mass caused by mediolateral undulation of the torso. These results bear an important implication for the study of arboreal locomotion: center of mass dynamics are at least as important as static positions. M. domestica is a good representative for a primitive mammal, and comparisons with arboreal specialists will shed light on how proficient arboreal locomotion evolved. [Copyright &y& Elsevier]

Abstract: The small mineral-binding bone protein, osteocalcin, has been applied in a number of studies on ancient bone due to predictions of its long-term stability. However, the intact protein has not been shown to survive in ancient bone devoid of DNA, which is a much more phylogenetically informative biomolecule. In this investigation, the survival of osteocalcin is directly compared to the amplification of mtDNA in a set of 34 archaeological samples from four sites throughout Europe. We also present unpublished osteocalcin sequences of seven mammalian species in addition to the 19 published sequences to highlight phylogenetic limitations of this protein. The results indicate that the intact osteocalcin molecule survives less in archaeological samples than mtDNA and is more subject to the temperature of the archaeological site. Amino acid analyses show the persistence of the dominant protein collagen in samples that failed both osteocalcin and mtDNA analyses. The implications these findings present for biomolecular species identification in archaeological and palaeontological material are that, although proteins do survive beyond ancient DNA, osteocalcin does not appear to be the most ideal target. [Copyright &y& Elsevier]

South American (SA) opossum lower esophageal sphincter (LES) circular smooth muscle relaxes by activation of enteric nerves elicited by EFS (electrical field stimulation, 0.5 ms, 48 V, 0.5–8 Hz for 10 s). The identity of the mediator released and the cellular mechanism, however, remain to be fully elucidated. The purpose of this study was to determine the effect of the enzyme soluble guanylate cyclase (cGC) inhibitors, cystamine (100 μm), methylene blue (30 μm), LY 83583 (6-anilino-5,8 quinoledione, 10 μm) and ODQ (H-[1,2,4]oxadiazolo[4,3]quinoxalin-1-one, 1 μm) on the relaxations induced by EFS and by exogenous NO (nitric oxide, 0.5 mm) or NO-donors on SA opossum LES smooth muscle strips. EFS caused frequency-dependent relaxations, which were inhibited by NO-synthase inhibitors and abolished by tetrodotoxin. Cystamine did not affect relaxations caused by EFS and NO or NO-donor. Methylene blue also failed to affect EFS-caused relaxations, although it was capable of inhibiting relaxation induced by NO. LY 83583 inhibited relaxations induced by NO, but did not affect those induced by EFS or by SNAP and HXA. ODQ abolished relaxations caused by EFS at lower frequencies and by HXA (hydroxylamine, 10 μm) and SNAP ( S-nitroso- N-acetyl penicillamine, 10 μm). Relaxations at higher frequencies of EFS and induced by SNP (sodium nitroprusside, 30 μm) and NO were only reduced by ODQ. These findings indicate that activation of the cGC can be involved in relaxations induced by EFS at lower frequencies, but other mechanisms can be involved at higher frequencies of EFS and caused by SNP or NO. [ABSTRACT FROM AUTHOR]

Abstract: The architecture of the amygdaloid complex of a marsupial, the opossum Didelphis aurita, was analyzed using classical stains like Nissl staining and myelin (Gallyas) staining, and enzyme histochemistry for acetylcholinesterase and NADPH-diaphorase. Most of the subdivisions of the amygdaloid complex described in eutherian mammals were identified in the opossum brain. NADPH-diaphorase revealed reactivity in the neuropil of nearly all amygdaloid subdivisions with different intensities, allowing the identification of the medial and lateral subdivisions of the cortical posterior nucleus and the lateral subdivision of the lateral nucleus. The lateral, central, basolateral and basomedial nuclei exhibited acetylcholinesterase positivity, which provided a useful chemoarchitectural criterion for the identification of the anterior basolateral nucleus. Myelin stain allowed the identification of the medial subdivision of the lateral nucleus, and resulted in intense staining of the medial subdivisions of the central nucleus. The medial, posterior, and cortical nuclei, as well as the amygdalopiriform area did not exhibit positivity for myelin staining. On the basis of cyto- and chemoarchitectural criteria, the present study highlights that the opossum amygdaloid complex shares similarities with that of other species, thus supporting the idea that the organization of the amygdala is part of a basic plan conserved through mammalian evolution. [Copyright &y& Elsevier]

Background: Equine protozoal myeloencephalitis (EPM) is a serious and often fatal neurologic disease of horses, but few studies have investigated risk factors. Objectives: To evaluate operation- and individual-level factors associated with likelihood of the occurrence of EPM. Animals: Data were collected as part of a study of the US equine industry from 1,178 operations representing 83.9% of horses and 51.6% of operations with ≥3 horses in 28 states. Methods: Probability-based sampling was used to enroll representative operations in a cross-sectional study. Interviews were conducted to collect information regarding health and management of horses. A nested case-control study was used to investigate risk factors among individual horses. Interview data were combined with climate data, human population density, and opossum regional ecology categories. Data were analyzed using logistic regression to identify risk factors for the occurrence of EPM. Results: Owners reported that 95% of EPM cases included in this study were diagnosed by veterinarians. Variables associated with EPM occurrence on premises included opossum regional ecology, reported exposure to small wildlife, climate, terrain, housing, choice of bedding material, method of storing feeds, equine stocking density, and primary use of horses. Among individual horses, age was most strongly associated with disease risk. Associations also were identified with sex, breed, primary use, and participation in competitions. Conclusions and Clinical Importance: Because the risk of EPM occurrence on operations is closely tied to factors that impact exposure to opossums, their feces, and their environment, controlling these exposures may be important in preventing the occurrence of EPM. [ABSTRACT FROM AUTHOR]

Currently, the use of anti-venoms is the only available treatment for envenomations caused by poisonous animals, namely snake, scorpion, spider, tick, and jellyfish. Anti-venoms are generally produced in big animals, mostly in horses. A large percentage of the population in some regions is allergic to horse proteins. Several animals are known to be resistant to snakebites, and the anti-hemorrhagic and anti-lethal components have been isolated from sera of opossum, mongoose, meerkat, and hedgehog, as well as from poisonous and non-poisonous snakes. Lethal toxin neutralizing factor (LTNF) was isolated in purity from opossum (D. virginiana) serum by high-pressure liquid chromatography. The molecular weight of LTNF is 63 kDa, and it does not form precipitates with venoms or toxins by immune diffusion test. Death due to intraperitoneal injection of a predetermined lethal dose of venom from major families of snakes (Crotalidae, Elapidae, Viperidae, and Hydrophiidae) is prevented in mice by subsequent intraperitoneal inoculation of LTNF. Furthermore, LTNF neutralizes the lethality of scorpion and bee venoms and toxins from various animal, plant, and bacterial sources. Thus, natural LTNF from opossum serum has potential as a universal therapy for envenomations and other toxin exposure caused by animals, plants, and bacteria. [ABSTRACT FROM AUTHOR]

The ovarian histology, the structural and the ultrastructural characteristics of the folliculogenesis in Dideiphis albiventris were described in detail. Recent studies suggest that methatherian mammals have unusual reproductive cycle but there are few informations regarding the marsupials reproductive life. Despite of the opossum folliculogenesis pattern resembles methatherian and eutherian pattern in many aspects, the analysis shows some peculiar features of the oocyte structure and ultrastructure that make available new data on the reproductive biology of marsupials. [ABSTRACT FROM AUTHOR]

Data on the reproductive patterns of the Brazilian slender opossum (Marmosops paulensis) were collected in an area of Montane Atlantic forest, southeastern Brazil, from August 2002 to July 2004. Reproduction occurred from September to March in both years, a period of high food supply, probably as a way to maximize survival of juveniles. There was nearly zero postmating survival, thus, no individual took part in more than 1 breeding event. This pattern characterizes a semelparous life history, which has been described in other small didelphids and dasyurids. Females were reproductively active during months with longer day lengths and abundant fruit supply. Breeding seems to be initiated by a 12L:12D photoperiod and a rapid rate of change in day length, as demonstrated in semelparous dasyurids. Hence, the effect of photoperiodic cues on the onset of reproduction also may stand for other semelparous didelphids. We suggest that fruit availability controlled the length of breeding activity in M. paulensis, and it could play a role in the occurrence of semelparity in this species. However, semelparity may occur only due to phylogenetic constraints, whereas food supply works as a selective force maintaining this trait. [ABSTRACT FROM AUTHOR]

Abstract: Antibodies directed against calcium-binding proteins (CaBPs) parvalbumin, calbindin-D28k and calretinin were used as neuronal markers to identify and characterize different principal cell types in the mammalian cochlear nucleus. For this purpose, double immunofluorescence labeling and the combination of CaBP-labeling with pan-neuronal markers were applied to analyze the CaBPs distribution in neurons of the cochlear nucleus (CN) of the Mongolian gerbil (Meriones unguiculatus) and the gray short-tailed opossum (Monodelphis domestica). Despite of the fact, that these two mammalian species are not closely related, principal cell types in the CN of the two species showed many corresponding morphological features and similarities in immunolabeling of the CaBPs. Parvalbumin seems not to be suited as a differential neuronal marker in the CN since it is expressed by almost all neurons. In contrast, calbindin and calretinin were more restricted to specific cell types and showed a mostly complementary labeling pattern. As one of the most interesting findings, calbindin and calretinin were predominantly found in subpopulations of globular bushy cells and octopus cells in the ventral CN. Such a neuron-specific CaBP-expression in subpopulations of morphologically defined cell types argues for a more refined classification of CN cell types in Meriones and Monodelphis. Additionally, other cell types (cartwheel cells, unipolar brush cells, fusiform cells) were marked with calbindin or calretinin as well. Calretinin staining was predominantly observed in auditory nerve fibers and their endings including endbulbs of Held in Meriones. Spherical bushy cells showed a different calretinin-immunolabeling in Meriones and Monodelphis. This species-specific difference may be related to adaptive differences in auditory function. [Copyright &y& Elsevier]

Damage to white matter in some premature infants exposed to intrauterine infections is thought to involve disruption of the blood–brain barrier. We have examined the effect of minocycline, an agent reported to reduce brain damage resulting from inflammation, on inflammation-induced disruption of the blood–brain barrier and damage to white matter. Post-natal marsupial opossums ( Monodelphis domestica) were studied as most brain development in this species occurs after birth. Single intraperitoneal lipopolysaccharide (LPS) injection (0.2 mg/kg) with or without minocycline (45 mg/kg) at post-natal day (P)35 caused short-lasting barrier breakdown to plasma proteins but not to 14C-sucrose. By P44, blood–brain barrier integrity was intact but a reduced volume of white matter was present. At P44 after prolonged inflammation (5 × 0.2 mg/kg LPS at 48 h intervals), proteins from blood were observed within brain white matter and permeability to 14C-sucrose in the hindbrain increased by 31%. The volume of the external capsule and the proportion of myelin were 70 and 57%, respectively, of those in control animals. Minocycline administered during prolonged inflammation restored blood–brain barrier integrity but not LPS-induced damage to white matter. These data suggest that long-term changes in blood–brain barrier permeability occur only after a prolonged period of inflammation during development; however, damage to white matter can result from even a short-lasting breakdown of the barrier. Manipulation of the inflammatory response may have implications for prevention of some developmentally induced neurological conditions. [ABSTRACT FROM AUTHOR]

Abstract: α-Defensins are essential molecules of the innate immune system that have broad spectrum antimicrobial activity against a range of bacteria and viruses. To date, α-defensins have only been identified in the Euarchontoglires branch of the mammals. This has led to speculation that α-defensins may be specific to this group, a somewhat surprising finding, given their importance in the immune system. The mammalian genome project provided us with the opportunity to search for α-defensins in previously unexamined mammalian superorders. Using hidden Markov model (HMM) profile searching, we report the discovery of α-defensins in the African savanna elephant, the lesser hedgehog tenrec, and the nine-banded armadillo genomes representing two of the most basal mammalian superorders, Afrotheria and Xenarthra. Furthermore, we identify an α-defensin-like gene in the gray short-tailed opossum, suggesting that α-defensins may have evolved much earlier than previously thought, before the divergence of placental mammals and marsupials approximately 130mya. [Copyright &y& Elsevier]

In comparison with many mammals, there is limited knowledge of the role of pheromones in conspecific communication in the gray short-tailed opossum. Here we report that mitral/tufted (M/T) cells of the accessory olfactory bulb (AOB) of male opossums responded to female urine but not to male urine with two distinct patterns: excitation followed by inhibition or inhibition. Either pattern could be mimicked by application of guanosine 5′-O-3-thiotriphosphate and blocked by guanosine 5′-O-2-thiodiphosphate, indicating that the response of neurons in this pathway is through a G-protein–coupled receptor mechanism. In addition, the inhibitor of phospholipase C (PLC), U73122, significantly blocked urine-induced responses. Male and female urine were ineffective as stimuli for M/T cells in the AOB of female opossums. These results indicate that urine of diestrous females contains a pheromone that directly stimulates vomeronasal neurons through activation of PLC by G-protein–coupled receptor mechanisms and that the response to urine is sexually dimorphic. [ABSTRACT FROM AUTHOR]

The data published on reproduction of the species of the genus Didelphis (Didelphimorphia, Didelphidae) were compiled and analysed to identify general patterns. The duration of the breeding season for the Didelphis species varied from 12 months near the Equator to 6 months at latitude 25°S and varied inversely with latitude and litter size. The mean litter size varied from 4.2 in Colombia to 9.4 in New York and was positively associated with latitude and negatively with the duration of breeding season. We propose that the higher investment in production at higher latitudes was compensated by increased mortality owing to the seasonal variation in food availability and environmental variables in theses latitudes. [ABSTRACT FROM AUTHOR]