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How to manage harvest under great uncertainty is a fundamental question for many wildlife managers, particularly when resources necessary to estimate abundance or population trends are limited. The large Newfoundland and Labrador murre hunt is the only licensed harvest of seabirds in Canada. Though harvest of thick‐billed murres (Uria lomvia) and common murres (Uria aalge) has declined considerably since the 1960−1970s from >500,000 birds taken annually to approximately 100,000 annually in recent years, potential murre colony declines across the North Atlantic have again triggered concerns over the sustainability of murre harvest in Canada. The effect of current harvest is difficult to assess because there is considerable uncertainty in recent population size, trend, demographic rates, licensed harvest, fisheries bycatch, and illegal harvest. To assess the situation, we simulated the population size necessary to sustain current levels of approximated anthropogenic mortality using a potential biological removal approach, which simplifies and constrains population processes to a few key variables. Based on these simulations, the Canadian licensed harvest of thick‐billed murre is consistent with conservation management objectives, as is common murre licensed harvest and fisheries bycatch. Adding estimated illegal harvest resulted in unstainable mortality levels in both species. While wildlife managers will need to formally assess the relative costs and benefits of reducing uncertainty in this system through improved harvest and population monitoring, illegal harvest and commercialization need to be addressed to manage Canadian murre populations. Potential biological removal approaches can be a useful framework to assess harvest management decisions for marine birds and other data‐limited species. [ABSTRACT FROM AUTHOR]

Understanding the phenology of migration is fundamental to management of migratory gamebirds, in part because of the role migratory timing plays in setting harvest regulations. Migratory timing is particularly important for determining appropriate dates for hunting seasons, which may be selected to coincide with major periods of migration, according to local management objectives. We used global positioning system (GPS)‐transmitters to track American woodcock (Scolopax minor), characterize the timing of woodcock migration, and identify sources of variation in timing relative to current hunting season structures in eastern North America. We captured 304 woodcock in 3 Canadian provinces and 12 states from 2017 to 2020, primarily within the Eastern Woodcock Management Region. Using locations collected every 1.7 days on average, we assessed whether initiation, termination, or stopover timing of woodcock migration during fall and early spring varied geographically, differed among age and sex classes, or was influenced by individual body condition. During fall, woodcock migrating from summer use areas farther north and west (e.g., Ontario, Quebec, Canada) initiated and terminated migration earlier than woodcock migrating from areas farther south and east (e.g., Rhode Island, USA). Adult woodcock made multiday stopovers that were 3 days longer on average than juveniles and females made more stopovers on average (8.0 stopovers) compared to males (6.1 stopovers). During the onset of spring migration, woodcock that wintered farther west initiated migration before birds that spent the winter farther east, and males initiated migration on average 6 days earlier than females. Under the current 45‐day harvest regulatory framework in the United States, hunting seasons in northern breeding and southern wintering areas are generally consistent with migration phenology. At more intermediate latitudes, however, periods of migration are generally longer than 45 days, resulting in many circumstances where migrating woodcock are present during periods when hunting seasons are closed. Managers in mid‐latitude states could consider opening hunting seasons later, allowing hunters to harvest more migrant woodcock. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Animal Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

American woodcock (Scolopax minor; woodcock) are monitored, in part, by counts of displaying male woodcock collected via the American Woodcock Singing Ground Survey (SGS), which suggests long‐term, range‐wide declines in woodcock populations. Data from the SGS have been used extensively to develop conservation plans, direct management actions, and understand causes of decline. To avoid bias, the SGS should be timed to avoid spring migration, and the distribution of survey routes should coincide with woodcock breeding distribution. Our objectives for this research were to evaluate SGS timing with the phenology of male woodcock migration, relate the spatial coverage of the SGS to male woodcock breeding distributions, and explore other sources of variation in woodcock migration timing. We marked 133 male woodcock captured throughout eastern North America with global positioning system (GPS) transmitters during 2019–2022, and compared the timing of their spring migration with the spatiotemporal stratification of the SGS. Most woodcock (74%) completed migration prior to the onset of the SGS. In the northernmost SGS zone, a greater percentage of males (34%) continued migration during the survey window; however, the influence of this mismatch is offset because SGS routes were run more frequently during the second half of the window. Young woodcock completing their first spring migration took 8.6 days longer to do so, on average, compared to adults, and so were more likely to migrate during the SGS window. We found little evidence that timing of migration varied among years. Existing SGS routes cover the majority of male woodcock post‐migratory breeding distribution, with 90% of male woodcock establishing final breeding sites within the spatial coverage of the SGS. Our results confirm the SGS includes some migrating males, with the proportion relative to resident breeding males increasing in more northern survey strata. Our data suggests these errors are unlikely to bias trend estimates at large scales (e.g., within woodcock management regions), but there may be potential for bias at more local scales (e.g., state or provincial population indices). [ABSTRACT FROM AUTHOR]

Population models commonly assume that the demographic parameters are spatially invariant, but there is considerable evidence that population growth rate ( r) and the strength of density dependence (β) can vary over a species' range. To address this issue we developed a spatially explicit Gompertz population model based on the spatially varying coefficients approach to assess the spatial variation in population drivers. The model was fit to spatially stratified time series population estimates of the mallard Anas platyrhynchos in western North America. We included precipitation during the previous year and spring maximum temperature in the current year as environmental factors in the density dependent population model. Because density dependent models can give biased estimates for time series of abundance data, we fit a naïve model without informative priors and a model where we constrained the mean and variance of r to biologically realistic values that were derived via a comparative demography approach. In the naïve model, r and β were not separately identifiable and their values were overestimated, leading to unrealistic population growth. The naïve model also implied spatial variation in population r and the return time to equilibrium [1⁄(- β)] across the survey area. In contrast, in the informative model, r and the return time to equilibrium did not vary markedly among populations and were generally equal across populations. The effects of the climatic factors were similar across models. Population growth rates in the Prairie-pothole region were positively correlated with precipitation, while in Alaska rates were positively correlated with spring temperature. Although it has been argued in the past that adding ecological realism could help avoid the pitfalls associated with density dependent models, our results demonstrate that imposing constraints on the population parameters is still the best course of action. [ABSTRACT FROM AUTHOR]

Assessing spatial variation in waterfowl harvest probabilities from banding data is challenging because reporting and recovery probabilities have distinct spatial patterns that covary temporally with harvesting regulations, hunter effort, and reporting methods. We analyzed direct band recovery data from American black ducks banded on the Canadian breeding grounds from 1970 through 2010. Data were registered to a 1-degree grid and analyzed using hierarchical logistic regression models with spatially correlated errors to estimate the annual probabilities of band recovery and the proportion of individuals recovered in Canada. Probability of harvest was estimated from these values, in combination with independent estimates of reporting probabilities in Canada and the USA. Model covariates included estimates of hunting effort and factors for harvest regulation and band reporting methods. Both the band recovery processes and the proportion of individuals recovered in Canada had significant spatial structure. Recovery probabilities were highest in southern Ontario, along the Saint Lawrence River in Quebec, and in Nova Scotia. Black ducks breeding in Nova Scotia and southern Quebec were harvested predominantly in Canada. Recovery probabilities for juveniles were correlated with hunter effort, while the adult recoveries were weakly correlated with the implementation of stricter harvest regulations in the early 1980s. Mean harvest probability decreased in the northern portion of the survey area but remained stable or even increased in the south. Harvest probabilities for juveniles in 2010 exceeded 20% in southern Quebec and the Atlantic provinces. Our results demonstrate fine-scale variation in harvest probabilities for black duck on the Canadian breeding ground. In particular, harvest probabilities should be closely monitored along the Saint Lawrence River system and in the Atlantic provinces to avoid overexploitation. [ABSTRACT FROM AUTHOR]

Human immunodeficiency virus type 1 (HIV-1) transcription relies on its transactivating Tat protein. Although devoid of a signal sequence, Tat is released by infected cells and secreted Tat can affect uninfected cells, thereby contributing to HIV-1 pathogenesis. The mechanism and the efficiency of Tat export remained to be documented. Here, we show that, in HIV-1-infected primary CD4+ T-cells that are the main targets of the virus, Tat accumulates at the plasma membrane because of its specific binding to phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). This interaction is driven by a specific motif of the Tat basic domain that recognizes a single PI(4,5)P2 molecule and is stabilized by membrane insertion of Tat tryptophan side chain. This original recognition mechanism enables binding to membrane-embedded PI(4,5)P2 only, but with an unusually high affinity that allows Tat to perturb the PI(4,5)P2-mediated recruitment of cellular proteins. Tat–PI(4,5)P2 interaction is strictly required for Tat secretion, a process that is very efficient, as ∼2/3 of Tat are exported by HIV-1-infected cells during their lifespan. The function of extracellular Tat in HIV-1 infection might thus be more significant than earlier thought. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemical Engineering is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ERM (Ezrin/Radixin/Moesin) proteins are crosslinkers between plasma membrane proteins and the actin cytoskeleton, thereby involved in the formation of cell adhesion sites. Earlier work showed that Ezrin links syndecan-2 to the actin cytoskeleton. Here we provide evidence that the Ezrin N-terminal domain binds to the syndecan-2 cytoplasmic domain with an estimated KD of 0.71 μM and without the requirement of other proteins. We also studied the regions in the syndecan-2 cytoplasmic domain implicated in the binding to Ezrin. By truncating the syndecan-2 cytoplasmic domain and by oligopeptide competition assays we show that the Ezrin-binding sequence is not located in the positively charged juxtamembrane region (RMRKK), but in the neighboring sequence DEGSYD. We therefore conclude that the consensus sequence for Ezrin binding is unique among membrane proteins, suggesting a distinct regulation. [Copyright &y& Elsevier]

The current study focuses on the molecular mechanisms responsible for actin assembly on a defined membrane surface: the phagosome. Mature phagosomes were surrounded by filamentous actin in vivo in two different cell types. Fluorescence microscopy was used to study in vitro actin nucleation/polymerization (assembly) on the surface of phagosomes isolated from J774 mouse macrophages. In order to prevent non-specific actin polymerization during the assay, fluorescent G-actin was mixed with thymosin J34. The cytoplasmic side of phagosomes induced de novo assembly and barbed end growth of actin filaments. This activity varied cyclically with the maturation state of phagosomes, both in vivo and in vitro. Peripheral membrane proteins are crucial components of this actin assembly machinery, and we demonstrate a role for ezrin an(For moesin in this process. We propose that this actin assembly process facilitates phagosome/endosome aggregation prior to membrane fusion. [ABSTRACT FROM AUTHOR]

The interferon responsive element (IRE) of the 6-16 gene lies within two 39-bp elements in tandem. A purine-rich oligodeoxynucleotide, oligo(dN), was found to be able to pair with the purinerich strand of the IRE in an antiparallel orientation which led to triple-helix formation with Mg[SUP2+] being necessary for triplex stability. Footprinting analysis confirmed these results. The interaction between the IRE and the oligo(dN) was reversible and had a K[SUBd] equal to 20 nM. The two repeats of the 6-16 gene IRE can form a hinged DNA structure through pairing of their purine-rich regions: exonuclease Ill experiments support this model. The hybrid DNA structure leads to a parallel pairing of the purine strands of the 6-16 gene IRE and this conformation was shown to be destabilized by triplex formation. When co-transfected with a reporter gene whose promoter was under the control of the 6-16 gene IRE, the triple-helix-forming oligo(dN)s inhibit the interferon-induced stimulation of the reporter gene with complete inhibition being obtained with 1 pM oligo(dN) at the time of transfection. When added to the cell culture medium after transfection, the concentrations of oligo(dN) needed to obtain 50% inhibition of the interferon effect on gene transcription must be 50-100 times higher. Besides the existence of a peculiar structure for the 6-16 gene IRE, the possibility of interfering with gene expression by means of oligo(dN)s is demonstrated. [ABSTRACT FROM AUTHOR]

LLC-PKIL cells, a kidney-derived cell line, had sustained growth in a defined medium. When compared to the parent cell line growing with 10% fetal bovine serum, LLC-PKIL cells had about 100-times fewer vasopressin receptors. Upon modifications of the cell culture medium, the vasopressin response of the adenylate cyclase could be increased by more than 10-fold with a parallel increase in vasopressin receptor number. Using cells with high or low receptor densities, the stimulatory and inhibitory effects of N6-L-2-phenylisopropyl-adenosine on the modulation of the adenylate cyclase responsiveness to vasopressin were investigated. When high concentrations of GTP were added, low concentrations of phenylisopropyladenosine inhibited the enzyme, while higher concentrations were found to be stimulatory. The adenylate cyclase activity stimulated by vasopressin could only be inhibited by phenylisopropyladenosine under these conditions in membranes with high receptor density; only the increase in enzyme activity due to high GTP concentration was inhibitable. The analysis of the dependency of the adenylate cyclase activity as a function of the vasopressin concentrations showed that, besides reducing the maximum velocity of the system for vasopressin, the addition of phenylisopropyladenosine generated an heterogeneity in the adenylate cyclase response to vasopressin (as judged by a curvilinear Eadie plot). A high-affinity component in the adenylate cyclase response appeared when phenylisopropyladenosine was added. The growth of the cells in a medium containing adenosine deaminase gave results identical to those obtained for control cells. However, growing the cells with both phenylisopropyladenosine and adenosine deaminase abolished the inhibitory effects of the former on the adenylate cyclase and greatly reduced its stimulatory action. Under these conditions, the vasopressin response of the adenylate cyclase was not further regulated by phenylisoprophyladenosine. These results indicate a role of adenosine on vasopressin response, especially at low physiological concentrations of the hormone where a high-affinity component of the hormonal response could be demonstrated. [ABSTRACT FROM AUTHOR]

The effects of 17 non-ionic detergents on pig kidney plasma membrane adenylate cyclase were tested (digitonin; detergents from the Triton series: X45, X100, X102, X114, X165, X305, X405, N101; the Brij series: 35, 56, 96 and the Tween series: 20, 40, 60, 80, 85). Membranes (2.66 mg protein/ml) were treated with increasing amounts of detergent for 150 min at 0 °C. The adenylate cyclase activities present in treated membranes and in their corresponding non-sedimentable fractions were measured at 30 °C. Only detergents having hydrophilic lipophilic balance values from 12 to 14 were effective solubilizing agents. For these detergents, the solubilization yield was dependent on their structure. When solubilized adenylate cyclase kept at 0 °C was incubated at 30 °C, the enzyme catalytic activity exponentially decreased towards an equilibrium value with a half-time of 5 min. This temperature-dependent adjustment of enzyme activity was reversible. Its magnitude was dependent on the detergent used. A more progressive but less pronounced effect was observed with non-solubilizing detergents. The micellar form of detergent in the incubation medium was found to be responsible for the appearance of microheterogeneity in the population of solubilized enzyme molecules differing by the substrate accessibility. This effect was suppressed when reducing the detergent concentration in the incubation medium. [ABSTRACT FROM AUTHOR]

The effect of adding various Na+, K+ and Li+ salts was tested on the adenylate cyclase activity present in pig-kidney-medulla plasma membranes. Salts were found to exert dual effects: stimulation at lowest doses and inhibition at highest doses. The importance of the stimulatory effect depended on the addition of NaF, hormone or guanylyl 5′-imidodiphosphate (GMP-P(NH)P) in the incubation medium. In all cases, maximum effect (2-3.4-fold increase in activity) was observed in the presence of saturating amounts of (8-lysine)vasopressin. Rate of adenylate cyclase activation by GMP-P(NH)P was enhanced in the presence of salt. Basal adenylate cyclase activity stimulation by salt was highly dependent on the nature of the salt used. There was a 10% increase with NaSCN and a 210% increase with NaCl. The effects of salts could not be accounted for by a fluoride-like effect. Among all the tested salts, only lithium salts inhibited hormone-stimulated enzyme. The order of potency, Li+, Na+, K+, was found when considering the inhibitory effect observed with high salt concentrations. For anions, the stimulatory effect observed with low salt concentration was I-, SCN-, Br-, Cl-, N3-, HCOO- and CH3COO- in decreasing order of potency. Stimulatory effect of salt was observed when tested at 30 °C while highly inhibitory effect occurred at low temperature. Above 20 °C the energies of activation (Ea) were identical regardless of the presence of salt. At lower temperature, Ea was doubled in the presence of salt. All the stimulatory salts did not change the characteristics of adenylate cyclase activation by (8-lysine)vasopressin or its analogues, but stimulation ratio was enhanced. The above results cannot be entirely accounted for by a chaotropic action of ions on the membrane structure. [ABSTRACT FROM AUTHOR]