Subcellular Distribution of 3α-Hydroxysteroid Dehydrogenase and Antiestrogen Action on Androgen-Metabolizing Enzymes in Rat Pituitary Gland

Abstract: Gonadectomy of male rats led to a threefold increase of 3α-hydroxysteroid dehydrogenase (3α-HSDH) activity in pituitary homogenates that could be completely reversed by chronic administration of estradiol or 5α-dihydrotestosterone (DHT). 3α-HSDH was found to be distributed mainly between the 10,000 g and 100,000 g sediments from whole homogenates. The microsomal enzyme activity showed a substantial specificity for NADH whereas the cytosolic enzyme (100,000 g supernatant) demonstrated a slight preference for NADPH. The changes in V _max found in homogenates following gonadectomy and gonadal steroid administration reflected changes in NADH- linked activity of the microsomal, but not the cytosolic enzyme. Estradiol-induced suppression of NADH-linked 3α-HSDH activity in pituitary homogenates from gonadectomized rats of either sex was accompanied by a similar suppression of NADPH-linked 5α-reductase activity and a marked decrease of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release. In the ovariectomized rat chronic administration of nonsteroidal antiestrogens had strong estrogenic effects on 3α-HSDH activity and LH release, but not on 5α-reductase activity and FSH release. In the gonadectomized male rat, which was much less sensitive to intrinsic estrogenicity of the antiestrogens tested, nafoxidine completely blocked estradiol-induced suppression of 5α-reductase activity and FSH release and partially antagonized suppression of LH release. The trans -isomeric, substituted triphenylethylenes, tamoxifen, and enclomiphene, as well as nitromifene (mixture of trans and cis isomers) were able partially to counteract estradiol-induced suppression of 5α-reductase, but not 3α-HSDH activity. It is concluded that estradiol action on pituitary 5α-reductase, but not 3α-HSDH activity, involves an estrogen receptor mechanism.     

Assessment of interleukin 1 and interleukin 2 effects on cycling and noncycling murine thymocytes

When mouse thymocytes are stimulated with PHA, the proliferative response is very low, unless the culture medium is enriched with interleukin 1 (IL-1)- or interleukin 2 (IL-2)-containing supernatants. Cytofluorometric analyses show, however, that PHA stimulation generates a significant number of cells with increased RNA content (transition from the G₀ to G₁ phase of the cell cycle). If IL-2 is added to such cultures, the activated cells complete their process of RNA synthesis and then enter the S phase. The use of IL-2-containing culture medium thus permits one to obtain a high correlation between the number of g₁ cells and [³H]thymidine incorporation (r = 0.97). Enrichment with IL-1-containing supernatants also results in a statistically significant correlation (r = 0.68), but the regression lines are markedly different for the two interleukins (s = 20.3 for IL-2 and s = 9.2 for IL-1), when analyzed after 48 hr of incubation. These observations suggest that the G₁ phase must be divided into two subcompartments, G_1a and G_1b, the G_1a-G_1b transition being an IL-2-dependent event. If the number of G_1b cells is used to establish correlations with [³H]thymidine incorporation, all values fall on the same regression line, regardless of culture conditions and of the addition of interleukins. It is concluded that IL-2 regulates lymphocyte proliferation at the level of RNA synthesis (G_1a-G_1b transition) rather than that of DNA synthesis (G₁-S transition).     

IgG opsonization of HIV impedes provirus formation in and infection of dendritic cells and subsequent long-term transfer to T cells

Already at initial phases of infection, HIV is coated with complement fragments. During the chronic phase, when HIV-specific IgGs appear, the virus circulates immune complexed with IgG and complement. Thus, we studied the interaction of dendritic cells (DCs) and DC-T cell cocultures with complement (C)-opsonized and C-IgG-opsonized HIV. HIV infection of monocyte-derived DCs and circulating BDCA-1-positive DCs was significantly reduced upon the presence of virus-specific but non-neutralizing IgGs. DCs exposed to C-Ig-HIV or IgG-opsonized HIV showed an impaired provirus formation and p24 production and a decreased transmission rate to autologous nonstimulated T cells upon migration along a chemokine gradient. This reduced infectivity was also observed in long-term experiments, when T cells were added delayed to DCs exposed to IgG-coated HIV without migration. Similar kinetics were seen when sera from HIV-1-infected individuals before and after seroconversion were used in infection assays. Both C- and C-IgG-opsonized HIV were captured and targeted to a tetraspanin-rich endosome in immature DCs, but differed with respect to MHC class II colocalization. The reduced infection by IgG-opsonized HIV is possibly due to interactions of virus-bound IgG with FcgammaRIIb expressed on DCs. Therefore, the intracellular fate and transmission of immune-complexed HIV seems to differ depending on time and opsonization pattern.     

Phylogeny and phylogeography of the genus Geothelphusa (Crustacea: Decapoda, Brachyura, Potamidae) in southwestern Taiwan based on two mitochondrial genes

Eleven species of Geothelphusa have been reported from southwestern Taiwan (Tainan, Kaohsiung and the northern part of Pingtung counties): G. albogilva Shy, Ng, and Yu, 1994; G. ancylophallus Shy, Ng, and Yu, 1994; G. caesia Shy, Ng, and Yu, 1994; G. lili Chen, Cheng, and Shy, 2005; G. nanhsi Shy, Ng, and Yu, 1994; G. neipu Chen, Cheng, and Shy, 1998; G. olea Shy, Ng, and Yu, 1994; G. pingtung Tan and Liu, 1998; G. shernshan Chen, Cheng, and Shy, 2005; G. tsayae Shy, Ng, and Yu, 1994 and G. wutai Shy, Ng, and Yu, 1994. Comparisons of DNA sequences encoding parts of the mitochondrial large subunit (16S) rRNA and cytochrome oxidase subunit I (COI) genes revealed three major clades, of which one is the species G. ancylophallus, and the other two are species groups here referred to as the G. olea and G. pingtung clades. Geothelphusa ancylophallus is geographically restricted and adapted to an ecologically challenging habitat with an unstable water supply and uneven topology. The G. olea clade (G. olea, G. caesia, G. nanhsi, G. tsayae, and G. wutai) is widely distributed throughout central-western and southwestern Taiwan. The G. pingtung clade (G. pingtung, G. neipu and G. shernshan) is confined to southwestern Taiwan between the previously defined southernmost clades of G. tawu, G. albogilva, and G. ferruginea, and the G. olea clade to the north. It includes an isolated population on distant Chaishan Mountain near Taiwan Strait, which probably dispersed from the peripheral hills of the Central Range during the early Pleistocene. The available genetic evidence indicates that the differential coloration observed in members of the G. olea and G. pingtung clades is not reflected in mtDNA, appears to be dependent on environmental conditions, food, etc., and has little value as a taxonomic character. Possible geological events and climatic factors responsible for the historic isolation of the different freshwater crab clades in southwestern Taiwan are discussed in detail.     

Flight initiation distance and escape behavior in the black redstart (Phoenicurus ochruros)

There are many anti‐predatory escape strategies in animals. A well‐established method to assess escape behavior is the flight initiation distance (FID), which is the distance between prey and predator at which an animal flees. Previous studies in various species throughout the animal kingdom have shown that group size, urbanization, and distance to refuge and body mass affect FID. In most species, FID increases if body mass, group size or distance to refuge decreases. However, how age and sexual dimorphism affect FID is rather unknown. Here, we assess the escape behavior and FID of the black redstart (Phoenicurus ochruros), a small turdid passerine. When approached by a human, males initiated flights later, that is allowing a closer approach than females. Males of this species are more conspicuous, and therefore, may exhibit aposematism to deter potential predators or are less fearful than females. Additionally, juveniles fled at shorter distances and fled to lower heights than adults. Lastly, concerning escape strategy, black redstarts, unless other passerine birds, fled less often into cover, but rather onto open or elevated spots. Black redstarts are especially prone to predation by ambushing predators that might hide in cover. Hence, this species most likely has a higher chance of escaping by fleeing to an open spot rather than to a potentially risky cover.     

De-ubiquitinating proteases USP2a and USP2c cause apoptosis by stabilising RIP1

Dynamic ubiquitination impacts on the degradation of proteins by the proteasome as well as on their effects as signalling factors. Of the many cellular responses that are regulated by changes in ubiquitination, apoptosis has garnered special attention. We have found that USP2a and USP2c, two isoforms of the ubiquitin-specific protease USP2, cause cell death upon ectopic expression. We show that both USP2 isoforms can control the ubiquitination status of many proteins but from a panel of potential targets only the protein level of RIP1 was increased by these enzymes. This effect is responsible for the activity of USP2a and USP2c to cause cell death. Both enzymes likewise de-ubiquitinate TRAF2, a ubiquitin-ligase in the TNFR1 complex. Whilst this and the similar sub-cellular localisations of both enzyme isoforms indicate a substantial overlap of activities, inactivation by RNAi revealed that only the knock-down of USP2c resulted in apoptosis, whilst targeting USP2a did not have any consequence on the cells' survival. Consequently, we focussed our studies on USP2a and found that TRAF2 inhibits USP2a's effect on K48- but not on K63-linked ubiquitin chains. Hence, the ratio between USP2a and TRAF2 protein levels determines the cells' sensitivity to cell death.     

Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS

This study aims at substituting the essential functions of photoreceptors in patients who are blind owing to untreatable forms of hereditary retinal degenerations. A microelectronic neuroprosthetic device, powered via transdermal inductive transmission, carrying 1500 independent microphotodiode-amplifier-electrode elements on a 9 mm² chip, was subretinally implanted in nine blind patients. Light perception (8/9), light localization (7/9), motion detection (5/9, angular speed up to 35 deg s⁻¹), grating acuity measurement (6/9, up to 3.3 cycles per degree) and visual acuity measurement with Landolt C-rings (2/9) up to Snellen visual acuity of 20/546 (corresponding to decimal 0.037 or corresponding to 1.43 logMAR (minimum angle of resolution)) were restored via the subretinal implant. Additionally, the identification, localization and discrimination of objects improved significantly (n = 8; p < 0.05 for each subtest) in repeated tests over a nine-month period. Three subjects were able to read letters spontaneously and one subject was able to read letters after training in an alternative-force choice test. Five subjects reported implant-mediated visual perceptions in daily life within a field of 15° of visual angle. Control tests were performed each time with the implant''s power source switched off. These data show that subretinal implants can restore visual functions that are useful for daily life.     

A multilocus sequence typing (MLST) approach to diminish the problems that are associated with DNA barcoding: A reply to Stahlhut et al. (2012)

In a recent Perspective, Stahlhut et al. (2012) argued that potential Wolbachia-induced effects on inheritance patterns of mitochondrial DNA do not significantly affect DNA barcoding efforts. Since this hypothesis can be readily tested, we suggest to do so by including multiple, nuclear markers in DNA barcoding studies.     

Soil seed bank contributes significantly to genetic variation of Hypericum sinaicum in a changing environment

The contribution of soil seed bank of a desert endemic plant species in maintaining genetic diversity has been addressed in this paper through investigating the differences in genetic diversity and structure (using AFLP markers) between plants grown from soil seed bank and standing crop plants within and among five populations of H. sinaicum growing at St. Katherine Protectorate, southern Sinai, Egypt. Standard genetic diversity measures showed that the molecular variation within and among populations was highly significantly different between standing crop and soil seed bank. While soil seed bank had lower genetic diversity than standing crop populations, pooling soil seed bank with standing crop samples resulted in higher diversity. The results revealed also that soil seed bank had lower differentiation (7 %) than among populations of the standing crop (18 %). Results of neighbor-joining, Bayesian clustering and principal coordinate analysis showed that soil seed banks had a separate gene pool different from standing crop. The study came to the conclusion that the genetic variation of the soil seed bank contributes significantly to the genetic variation of the species. This also stresses the importance of elucidating the genetic diversity and structure of the soil seed bank for any sound and long-term conservation efforts for desert species. These have been growing in small-size populations for a long time that any estimates gained only from aboveground sampling of populations may be ambiguous.