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The luminal uterine epithelial cells are the first point of contact with the implanting blastocyst. Dramatic changes occur in the structure and function of these cells at the time of receptivity including changes in the lateral junctional complex. While these morphological changes are important for uterine receptivity, currently there is no known mechanism of regulation of the lateral junctional complexes. Rab13, a member of the Rab (Ras-related in the brain) family of GTPases has a critical role in endosomal trafficking to the lateral plasma membrane and is involved in modulation of the tight junction in several cell types. The aim of this study is to investigate the role of Rab13 in changes to the lateral junctional complex at the time of receptivity. Immunofluorescence microscopy demonstrated no association between Rab13 and ZO-1 (a tight junction protein) or Rab13 and E-cadherin (an integral component of adherens junctions). Co-localisation was demonstrated between Rab 13 and desmoglein-2 at the time of fertilization and also at receptivity suggesting involvement of Rab13 in relocalisation of desmoglein-2 and formation of giant desmosomes in the apical part of the lateral plasma membrane at the time of uterine receptivity. We suggest that despite the loss of the adherens junction at the time of receptivity, the presently reported redistribution of desmosomes regulated by Rab13 allows the uterine epithelium to maintain structural integrity. [ABSTRACT FROM AUTHOR]

The angiogenic factor vascular endothelial growth factor-A (VEGFA) plays a critical role during early pregnancy in many species including the rat, and any alterations in VEGFA levels can severely impact blastocyst implantation rates. The rat ovarian hyperstimulation (OH) model is useful in studying how the induction of superovulation affects VEGFA levels and endometrial receptivity to blastocyst implantation. The present study shows that the major isoform in the rat uterus, Vegf188, is reduced at the time of receptivity in OH compared to normal pregnancy, whereas there is no change in Vegf164 and Vegf120 messenger RNA (mRNA). The VEGFA receptor 2 (VEGFR2) protein levels are also reduced at the time of receptivity in OH. Our ovariectomy studies show that Vegf164, Vegf188, and Vegf120 are significantly decreased by estrogen, and, to a lesser extent progesterone, when compared to control animals. Although no change in the percentage of endometrial blood vessels was seen across all stages of pregnancy, at the time of receptivity in OH pregnancies, blood vessels were typically larger compared to other stages. The altered progesterone- estrogen ratio seen in OH, taken together with our ovariectomy studies, explains the changes to Vegfa mRNA in OH at the time of receptivity. Since VEGFA is important during implantation, the changes to Vegfa and VEGFR2 levels in the endometrium may help explain the observed lower endometrial receptivity following OH. This study aimed to analyse how ovarian hyperstimulation alters the levels of vascular endothleial growth factor and its major receptor, VEGFR2 in the uterus in a rat model. [ABSTRACT FROM AUTHOR]

During early pregnancy, uterine epithelial cells (UECs) become less adherent to the underlying basal lamina and are subsequently removed so the blastocyst can invade the underlying stroma. This process involves the removal of focal adhesions from the basal plasma membrane of UECs. These focal adhesions are thought to be internalized by caveolae, which significantly increase in abundance at the time of blastocyst implantation. A recent in vitro study indicated that prominin-2 prevents the formation of caveolae by sequestering membrane cholesterol. The present study examines whether prominin-2 affects the formation of caveolae and loss of focal adhesions in UECs during normal and ovarian hyperstimulation (OH) pregnancy in the rat. At the time of fertilization during normal pregnancy, prominin-2 is distributed throughout the basolateral plasma membrane. However, at the time of implantation and coincident with an increase in caveolae, prominin-2 is lost from the basal plasma membrane. In contrast, prominin-2 remains in the basolateral plasma membrane throughout OH pregnancy. Transmission electron microscopy showed that this membrane contained few caveolae throughout OH pregnancy. Our results indicate that prominin-2 prevents the formation of caveolae. We suggest the retention of prominin-2 in the basal plasma membrane during OH pregnancy prevents the formation of caveolae and is responsible for the retention of focal adhesions in this membrane, thereby contributing to the reduced implantation rate observed after such treatments. [ABSTRACT FROM AUTHOR]

Uterine luminal epithelial cells (UECs) undergo the plasma membrane transformation in the transition to receptivity. This involves transient alterations in the apical junctional complex (AJC) including increases to the depth and complexity of the tight junction, loss of the adherens junction, and a decrease in the number of desmosomes along the lateral cell membranes. Nectin-3 is key protein involved in the structure and function of the AJC. This study, used immunofluorescence, Western blotting, colocalization, and coimmunoprecipitation analyses, to investigate whether nectin-3 was present in the rat uterus and was regulated by hormones and the blastocyst during early pregnancy. The results showed that nectin-3 was present in UECs as 3 molecular weight protein isoforms (80 kDa, 60 kDa, and 32 kDa). At the time of fertilization (day 1 of pregnancy), nectin-3 was localized basally, but at the time of implantation, (day 6 of pregnancy) when UECs were receptive, nectin-3 increased in the cellular junctions. When UECs returned to the nonreceptive state (day 9 of pregnancy), nectin-3 redistributed back to the cell cytoplasm. This study also showed that nectin-3 localization at the cell junctions was likely to be controlled by progesterone; however, neither ovarian hormones nor the blastocyst regulated protein abundance. This study further showed that while nectin-3 localized to the tight junction at the time of implantation, it did not interact with occludin or l-afadin. These results suggest that at the time of implantation, nectin-3 may contribute to the formation of the tight junction in a protein complex independent from occludin and l-afadin. [ABSTRACT FROM AUTHOR]

Nanocrystals are under active investigation because of their interesting size-dependent properties and potential applications. Silicon nanocrystals have been studied for possible uses in optoelectronics, and may be relevant to the understanding of natural processes such as lightning strikes. Gas-phase methods can be used to prepare nanocrystals, and mass spectrometric techniques have been used to analyse Au and CdSe clusters. However, it is difficult to study nanocrystals by such methods unless they are synthesized in the gas phase. In particular, pre-prepared nanocrystals are generally difficult to sublime without decomposition. Here we report the observation that films of alkyl-capped silicon nanocrystals evaporate upon heating in ultrahigh vacuum at 200 °C, and the vapour of intact nanocrystals can be collected on a variety of solid substrates. This effect may be useful for the controlled preparation of new quantum-confined silicon structures and could facilitate their mass spectroscopic study and size-selection. [ABSTRACT FROM AUTHOR]

Embryogenic callus development, plant regeneration, and plant recovery were achieved from immature cotyledon explants of cultivated tea, when cultured on MS basal medium. The somatic embryo induction frequency was influenced when the medium was supplemented with 1 μM auxin (NAA, NOA, 2,4-D, TPB, and PBOA) in combination with cytokinin (0.5 μM BA, KIN) or 10% CM. The highest somatic embryo induction frequency was obtained using PBOA + BA or PBOA + KIN treatments. All auxins except 2,4-D stimulated rhizogenesis using 0.8% and l.5% agar concentrations, and differentiation of a characteristic swelling and friable callus from the exposed surface of the explant that remained nonembryogenic. Conversely, the novel auxins TPB and PBOA at 1 μM concentration with 3% or 6% agar, produced somatic embryo induction, while at 0.8% and 1.5% produced nonembryogenic callus. Explants isolated proximal to the zygotic embryonal axis showed a greater somatic embryo induction frequency than did the distal explants. The embryogenic competence was maintained through repetitive embryogenesis for a period of over 18 months. The somatic embryos developed into plantlets when incubated on hormone-free medium. The conversion frequency was increased by 50% in MS medium containing 1 μM Brassin and 0.8% agar. Concentration of agar at 3% and 6% decreased the conversion frequency and promoted anomalous plantlet development. The normal plantlets were treated with 1 μM IAN, 1 μM Brassin and 10 μ Phloroglucinol in liquid MS medium for 15 d, where profuse lateral roots were induced favoring a high rate of plant recovery. [ABSTRACT FROM AUTHOR]

Sendai viral infection enhances mice lung response to Saccharopolyspora rectivirgula (SR). The mechanisms of this viral enhancement remain unclear. The present study was done to verify if the viral infection was required and if the presence of the viral infection needed to be given simultaneously with the SR antigen for the enhanced response to occur. In a first experiment groups of C57BL/6 mice were instilled concomitantly with SR and live or inactivated Sendai virus. In a second experiment the viral infection in the appropriate group preceded the SR challenges by 4 weeks. As reported previously SR induced a cellular inflammatory response. This effect of SR was enhanced by the viral infection but not by inactivated virus particles. Total lavage cells 3 weeks after the virus inoculation in the appropriate groups were: saline = 69 ± 15 × 10; SR = 678 ± 104 × 10; Sendai = 277 ± 61 × 10; inactivated Sendai = 73 ± 23 × 10; SR + Sendai = 1232 ± 232 × 10; SR + inactivated Sendai = 515 ± 54 × 10. In the second experiment, where the infection preceded the SR challenge, no enhancement was observed. We conclude that Sendai virus enhances mice lung response to SR by an infectious process when both SR and the virus are present simultaneously. [ABSTRACT FROM AUTHOR]