Seasonal variation in the regulation of redox state and some biotransformation enzyme activities in the barn swallow (Hirundo rustica L.)

Little is known of the normal seasonal variation in redox state and biotransformation activities in birds. In long-distance migratory birds, in particular, seasonal changes could be expected to occur because of the demands of migration and reproduction. In this study, we measured several redox parameters in the barn swallow (Hirundo rustica L.) during the annual cycle. We captured the wintering barn swallows before spring migration in South Africa, and we captured the barn swallows that arrived in spring, bred in summer, and migrated in autumn in Finland. The redox status and biotransformation activities of barn swallows varied seasonally. Wintering birds in South Africa had high biotransformation activities and appeared to experience oxidative stress, whereas in spring and summer, they showed relatively low redox (superoxide dismutase [SOD], catalase [CAT], and glutathione reductase [GR]) and biotransformation enzyme activities. Autumn birds had very low biotransformation enzyme activities and low indication of oxidative stress but high activity of some redox enzymes (GR and glucose 6-phosphate dehydrogenase [G6PDH]). High activities of some redox enzymes (SOD, GR, and G6PDH) seem to be related to migration, whereas low activities of some redox enzymes (SOD, CAT, and GR) may be associated with breeding. Barn swallows in South Africa may experience pollution-related oxidative stress, which may hamper interpretation of normal seasonal variation in redox parameters.     

Fibroblast growth factor 8b causes progressive stromal and epithelial changes in the epididymis and degeneration of the seminiferous epithelium in the testis of transgenic mice

Transgenic (Tg) mice expressing human fibroblast growth factor 8b (FGF8-b) under the probasin promoter (Tg [Pbsn-FGF8] L2-L5Elo; hereafter referred to as FGF8-b-Tg) were shown to produce FGF8-b at high levels in the prostate and epididymis and at lower levels in the testis. The present study examined the effects of FGF8-b expression on the epididymis and testis. In old (age, >6 mo) FGF8-b-Tg mice, epididymides were frequently enlarged, with epithelial and stromal hypercellularity progressing upon aging to epithelial dysplasia and malignant transformation of stroma. In addition, oligospermia, dilatation of the duct, and inflammation were frequently observed in the epididymides. In association with the epididymal changes, some FGF8-b-Tg mice presented a degenerative seminiferous epithelium of the testis. Consistent with this observation, infertile males were found in two FGF8-b-Tg mouse lines. Masson trichrome staining and immunohistochemical analysis of smooth muscle actin, laminin, and androgen receptor revealed that changes in the epididymal stroma closely resembled those previously found in the prostates of the FGF8-b-Tg mice. Genes previously found to be upregulated in the prostate of FGF8-b-Tg mice, such as osteopontin (Spp1) connective tissue growth factor (Ctgf), apolipoprotein D (Apod), and FGF receptor 1c (Fgfr1-c), were also upregulated in the epididymides, suggesting that similar molecular mechanisms were active in both tissues. However, unlike in the prostate, the changes in the epididymal epithelium of the FGF8-b-Tg mice did not progress into invasive carcinoma. The results suggest that prolonged and enhanced FGF signaling induces dramatic changes in the epididymis and testis that lead to infertility in a portion of the FGF8-b-Tg males.     

Serological survey for potential disease agents of free-ranging cervids in six selected national parks from Germany

A total of 164 blood samples, collected from free-ranging red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in six German national parks (NP) between 2000 and 2002, were assayed for antibodies against nine viral disease agents. Antibodies were only detected against the alpha-herpesviruses; specifically, bovine herpesvirus-1 (BHV-1) (22 of 157, 14%), cervid herpesvirus-1 (17 of 157, 10.8%), and caprine herpesvirus-1 (11 of 159, 6.9%). Titers ranged from 4 to 102. Most of the seropositive sera, and those with the highest antibody titers, were from red and roe deer in the Harz and Hochharz NP, which are connected and allow migration between the two. The distribution and specificity of antibodies detected in individual deer suggests that the three alpha-herpesviruses are circulating in these deer populations. No antibodies were detected against bovine viral diarrhea virus, epizootic hemorrhagic disease virus, bovine leukemia virus, bluetongue virus, foot-and-mouth disease virus, or sheep and goat poxvirus.     

Proteolytic Function of GPI-Anchored Plasma Membrane Protease Yps1p in the Yeast Vacuole and Golgi

Yps1p is a member of the GPI-anchored aspartic proteases which reside at the plasma membrane of Saccharomyces cerevisiae. Here we show that in Δerg6 cells, where a late biosynthetic step of the membrane lipid ergosterol is blocked, part of Yps1p was targeted to the vacuole. There it overtook proteolytic functions of the Pep4p protease, resulting in processing of pro-CPY to CPY in cells lacking the PEP4 gene. Yps1p was enriched in membrane microdomains, as it could be isolated in detergent-insoluble complexes from both normal and Δerg6 cells. Vacuolar Yps1 caused degradation of a mammalian sialyltransferase ectodomain fusion protein (ST6Ne), which was directed from the Golgi to the vacuole in both normal and Δerg6 cells. Unexpectedly, ST6Ne was degraded also when arrested in the Golgi in a temperature-sensitive sec7–1 mutant. Newly synthesized Yps1p, in transit to the plasma membrane, was also involved in the Golgi-associated degradation. These data show that GPI-anchored proteases, whose biological roles are unknown, may reside and function in different subcellular locations.     

Midsummer spatial variation in methane efflux from stands of littoral vegetation in a boreal meso-eutrophic lake

1. Spatial variation of methane (CH₄) efflux from the littoral zone of a meso‐eutrophic boreal lake was studied with a closed‐chamber technique for three summer days in 22 vegetation stands, consisting of three emergent and three floating‐leaved species. 2. Between‐species differences in CH₄ emission were significant. The highest emissions were measured from the emergent Phragmites australis stands (0.5–1.7 mmol m^?2 h^?1), followed by Schoenoplectus lacustris > Equisetum fluviatile > Nuphar lutea > Sparganium gramineum > Potamogeton natans. Within‐species differences between stands were not significant. 3. In P. australis stands, the stand‐specific mean CH₄ emission was significantly correlated with solar radiation, probably indicating the role of effective pressurised ventilation on CH₄ fluxes. The proportion of net primary production emitted as CH₄ was significantly higher in P. australis stands (7.4%) than in stands of S. lacustris and E. fluviatile (both 0.5%). 4. In N. lutea stands, CH₄ efflux was negatively correlated with the mean fetch and positively with the percentage cover of leaves on the water surface. There were no differences in CH₄ efflux between intact N. lutea leaves and those grazed by coleopteran Galerucella nymphaeae. In S. graminaeum and P. natans stands, CH₄ effluxes were not related to any of the measured environmental variables. 5. For all vegetation stands, the biomass above water level explained about 60% of the observed spatial variation in CH₄ emission, indicating the important role of plants as gas conduits and producers of substrates for methanogens in the anoxic sediment.     

Large-scale geographical variation confirms that climate change causes birds to lay earlier

Advances in the phenology of organisms are often attributed to climate change, but alternatively, may reflect a publication bias towards advances and may be caused by environmental factors unrelated to climate change. Both factors are investigated using the breeding dates of 25 long-term studied populations of Ficedula flycatchers across Europe. Trends in spring temperature varied markedly between study sites, and across populations the advancement of laying date was stronger in areas where the spring temperatures increased more, giving support to the theory that climate change causally affects breeding date advancement.     

Loss of Occludin and Functional Tight Junctions, but Not ZO-1, during Neural Tube Closure—Remodeling of the Neuroepithelium Prior to Neurogenesis

Neuroepithelial cells can generate nonepithelial cells, the neurons. Here we have investigated, for chick and mouse embryos, the epithelial character of neuroepithelial cells in the context of neurogenesis by examining the presence of molecular components of tight junctions during the transition from the neural plate to the neural tube. Immunoreactivity for occludin, a transmembrane protein specific to tight junctions, was detected at the apical end of the lateral membrane of neuroepithelial cells throughout the chick neural plate. During neural tube closure, occludin disappeared from all neuroepithelial cells. Correspondingly, the addition of horseradish peroxidase to the apical side of the neuroepithelium by injection into the amniotic cavity of mouse embryos revealed the presence of functional tight junctions in the neural plate (Embryonic Day 8), but not the neural tube (Embryonic Day 9). In contrast to occludin, expression of ZO-1, a peripheral membrane protein of tight junctions, increased from the neural plate to the neural tube stage, also being confined to the apical end of the lateral neuroepithelial cell membrane. This localization coincided with that of N-cadherin, whose expression increased concomitantly with the disappearance of occludin. We propose that the loss of tight junctions from neuroepithelial cells reflects an overall decrease in their epithelial nature, which precedes the generation of neurons.     

Species of Heterobasidion host a diverse pool of partitiviruses with global distribution and interspecies transmission

We investigated the geographic occurrence and genetic diversity of partitiviruses among 247 Heterobasidion specimens representing seven species and originating from Europe, Asia, and North America. Based on sequence analysis, partitiviruses were relatively rare, and occurred only in about 5 % of the Heterobasidion isolates analyzed, constituting a minority (about 28 %) of all virus-infected [double-stranded RNA (dsRNA)-positive] isolates. Altogether ten virus strains were characterized in sequence: one complete genome sequence of 3893 bp, six complete RNA-dependent RNA polymerase sequences of 2000-2033 bp, and three partial polymerase sequences. Based on phylogenetic analysis, the virus strains were assigned into three putative partitivirus species: HetRV1 (Heterobasidion RNA virus 1), HetRV4, and HetRV5. Degenerate consensus primers were designed for RT-PCR detection of these virus species. HetRV1 occurred in five different Heterobasidion species, and resembled the previously described Heterobasidion annosum virus (HaV). Highly similar HetRV1 strains with 98 % nucleotide level similarity were found from H. parviporum (member of the H. annosum species complex) and H. australe (member of the H. insulare complex) growing in the same region in Bhutan. This observation suggests recent virus transmission between these taxonomically distant Heterobasidion species in nature. It was also shown that HetRV1 can be transmitted by mycelial contact between the H. annosum and H. insulare complexes. The two other virus species, HetRV4 and HetRV5, were closely related to the Amasya Cherry Disease-associated mycovirus, to Heterobasidion parviporum partitivirus Fr110B, and also to several plant-infecting alphacryptoviruses. These results are in accordance with the view of a close evolutionary relationship between partitiviruses of plants and fungi.     

Origin of symmetrical triradial chromosomes in human cells

We have collected 23 sporadic symmetrical triradial chromosomes (plus one D with duplicate satellites), 22 from cultured lymphocytes and one from a bone marrow cell. Fifteen triradials were from patients with Bloom's syndrome, and two from a Fanconi's anemia patient. The following chromosomes and chromosome groups were involved: 1, 2, 3, 4, 5, C (11 identified), D, and 17. The branchpoints were localized nonrandomly. Regions in or near centric heterochromatin were often involved. Some of the branchpoints are regions which also contain a high number of mitotic chiasmata. When the present sporadic triradials combined with those from the literature were compared with triradials with branchpoints in the fragile regions, the localized branchpoints were different in these two groups. Our conclusion that most — possibly all — symmetrical triradials are caused by partial endoreduplication is based on the following observations: the shape of the triradials which shows that the extra segments are paired with their intact sister chromatids and not with each other; the failure of X-rays in G₂ to increase the incidence of symmetrical triradials; the fact that in some cases the end of the extra segment is joined to its intact sister chromatid; and the occurrence of duplicate satellites.     

Endomitosis in human trophoblast

Summary Endopolyploidy, which arises through the duplication of DNA without accompanying nuclear division, occurs in large numbers of lower and higher plants and animals, including the best known, the salivary gland nuclei of Drosophila. Endomitosis is one of the processes leading to endopolyploidy, in which the stages of mitosis (prophase, metaphase, anaphase) take place inside the nuclear membrane and without spindle formation. In mammals, endomitosis has been observed in the trophoblast of the placenta of the mouse, rat and rabbit. This is the first report of endomitosis in a normal human tissue, the trophoblast of first trimester human placenta.This research was supported in part by the Foundation for Reproductive Research and Education, Inc., Northwestern University, Department of Obstetrics and Gynecology.