Analysis of Dysgenesis-Induced Lethal Mutations on the X Chromosome of a Q Strain of DROSOPHILA MELANOGASTER

The Q strain known as v6 was tested for its ability to induce X-linked lethal mutations in male and female hybrids from crosses with M strains in the P-M system of hybrid dysgenesis. All measurements of the mutation rate were made on the X chromosome derived from the v6 strain. The lethal rate for young hybrid males from the cross M female X v6 male was 1.11% per chromosome. For older males, it was only 0.44%, suggesting that there is less mutational or more repair activity in the germ cells of the older males or that mutant cells are selectively eliminated as the hybrid males age. The lethal rate for hybrid females from comparable crosses was approximately the same for both ages that were tested. However, it was substantially less than the rate for the hybrid males--only 0.26% per chromosome. Genetically identical hybrid females from reciprocal crosses also showed a low mutation rate, 0.13% per chromosome. Again, there was no difference between young and old flies. Mapping experiments established that most of the lethal mutations that were recovered from the male and female hybrids were located in two regions on the X chromosome, one between bands 14B13 and 15A9 , the other between bands 19A1 and 20A , which encompasses the maroonlike locus. More refined mapping of the lethals in the maroonlike region demonstrated that the vast majority of these affected a single gene located in band 19C4 . Cytological analysis of the lethal chromosomes revealed that several carried rearrangements, including inversions, duplications and deficiencies. Chromosome breakage occurred primarily in bands 14D1 -3 and 18F- 20A , and most of the breaks in the latter segment were located in 19C . However, rearrangements involving 19C and mutations of the gene in 19C4 were mutually exclusive events. In situ hybridization of a P element probe to the chromosomes of v6 demonstrated that P elements reside at a minimum of five sites on the X chromosome. These P element sites correspond to the mutational and breakage hot spots on that chromosome. The combined genetic and cytological data imply that most of the X-linked lethal mutations that occur in M X v6 hybrids are due to local P element action. Consideration of these and other data suggest that v6 is a weak P strain in the P-M system of hybrid dysgenesis and that other Q strains might also be regarded in this way.     

Comparative effects of trichothecene mycotoxins on bovine platelet function: Acetyl T-2 toxin,a more potent inhibitor than T-2 toxin

The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10^?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds.     

An extensive review on antifungal approaches in the treatment of mucormycosis

During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B ( 1 ) and isavuconazole ( 2 ) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole ( 3 ) and deferasirox ( 4 ) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 ( 5 ) and APX001A ( 6 ), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis.     

Monoclonal antibodies to rabbit liver cytochrome P-448

Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed.     

Saikosaponin-d,a novel SERCA inhibitor,induces autophagic cell death in apoptosis-defective cells

Autophagy is an important cellular process that controls cells in a normal homeostatic state by recycling nutrients to maintain cellular energy levels for cell survival via the turnover of proteins and damaged organelles. However, persistent activation of autophagy can lead to excessive depletion of cellular organelles and essential proteins, leading to caspase-independent autophagic cell death. As such, inducing cell death through this autophagic mechanism could be an alternative approach to the treatment of cancers. Recently, we have identified a novel autophagic inducer, saikosaponin-d (Ssd), from a medicinal plant that induces autophagy in various types of cancer cells through the formation of autophagosomes as measured by GFP-LC3 puncta formation. By computational virtual docking analysis, biochemical assays and advanced live-cell imaging techniques, Ssd was shown to increase cytosolic calcium level via direct inhibition of sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase pump, leading to autophagy induction through the activation of the Ca²⁺/calmodulin-dependent kinase kinase–AMP-activated protein kinase–mammalian target of rapamycin pathway. In addition, Ssd treatment causes the disruption of calcium homeostasis, which induces endoplasmic reticulum stress as well as the unfolded protein responses pathway. Ssd also proved to be a potent cytotoxic agent in apoptosis-defective or apoptosis-resistant mouse embryonic fibroblast cells, which either lack caspases 3, 7 or 8 or had the Bax-Bak double knockout. These results provide a detailed understanding of the mechanism of action of Ssd, as a novel autophagic inducer, which has the potential of being developed into an anti-cancer agent for targeting apoptosis-resistant cancer cells.     

Expression and characterization of GSK-3 mutants and their effect on beta-catenin phosphorylation in intact cells

Glycogen synthase kinase-3 (GSK-3) is a serine-threonine kinase that is involved in multiple cellular signaling pathways, including the Wnt signaling cascade where it phosphorylates beta-catenin, thus targeting it for proteasome-mediated degradation. Unlike phosphorylation of glycogen synthase, phosphorylation of beta-catenin by GSK-3 does not require priming in vitro, i.e. it is not dependent on the presence of a phosphoserine, four residues C-terminal to the GSK-3 phosphorylation site. Recently, a means of dissecting GSK-3 activity toward primed and non-primed substrates has been made possible by identification of the R96A mutant of GSK-3beta. This mutant is unable to phosphorylate primed but can still phosphorylate unprimed substrates (Frame, S., Cohen, P., and Biondi R. M. (2001) Mol. Cell 7, 1321-1327). Here we have investigated whether phosphorylation of Ser(33), Ser(37), and Thr(41) in beta-catenin requires priming through prior phosphorylation at Ser(45) in intact cells. We have shown that the Arg(96) mutant does not induce beta-catenin degradation but instead stabilizes beta-catenin, indicating that it is unable to phosphorylate beta-catenin in intact cells. Furthermore, if Ser(45) in beta-catenin is mutated to Ala, beta-catenin is markedly stabilized, and phosphorylation of Ser(33), Ser(37), and Thr(41) in beta-catenin by wild type GSK-3beta is prevented in intact cells. In addition, we have shown that the L128A mutant, which is deficient in phosphorylating Axin in vitro, is still able to phosphorylate beta-catenin in intact cells although it has reduced activity. Mutation of Tyr(216) to Phe markedly reduces the ability of GSK-3beta to phosphorylate and down-regulate beta-catenin. In conclusion, we have found that the Arg(96) mutant has a dominant-negative effect on GSK-3beta-dependent phosphorylation of beta-catenin and that targeting of beta-catenin for degradation requires prior priming through phosphorylation of Ser(45).     

An association of early puberty with disordered eating and anxiety in a population of undergraduate women and men

Eating and anxiety disorders are more prevalent in females, increase during adolescence, and are associated with early pubertal development. This study examined whether timing of puberty onset is associated with disordered eating and anxiety in a large sample of postpubertal male and female undergraduate students. Self-report questionnaires assessed timing of puberty, disordered eating, anxiety, alcohol use, personality, and sensation seeking. Females scored significantly higher on measures of disordered eating (binge eating, dietary restraint, eating concerns, and weight and shape concerns) and anxiety (state and trait anxiety) than did males. In addition, early maturing women and men scored significantly higher on measures of disordered eating and anxiety than on time or late maturing women and men. Measures of alcohol use, sensation seeking, and personality characteristics differed in males and females but did not vary with pubertal timing. Findings suggest that early puberty is associated with disordered eating and anxiety, and this association may be due to an organizational effect of pubertal hormones. Despite important differences in body fat composition, both males and females experiencing early puberty had an increased incidence of disordered eating. The fact that early puberty was associated with increased eating and anxiety symptoms in both sexes suggests that puberty may influence these symptoms through both biological and psychosocial mechanisms.     

Conservation of Forest Birds: Evidence of a Shifting Baseline in Community Structure

Background

Quantifying changes in forest bird diversity is an essential task for developing effective conservation actions. When subtle changes in diversity accumulate over time, annual comparisons may offer an incomplete perspective of changes in diversity. In this case, progressive change, the comparison of changes in diversity from a baseline condition, may offer greater insight because changes in diversity are assessed over longer periods of times. Our objectives were to determine how forest bird diversity has changed over time and whether those changes were associated with forest disturbance.

Methodology/Principal Findings

We used North American Breeding Bird Survey data, a time series of Landsat images classified with respect to land cover change, and mixed-effects models to associate changes in forest bird community structure with forest disturbance, latitude, and longitude in the conterminous United States for the years 1985 to 2006. We document a significant divergence from the baseline structure for all birds of similar migratory habit and nest location, and all forest birds as a group from 1985 to 2006. Unexpectedly, decreases in progressive similarity resulted from small changes in richness (<1 species per route for the 22-year study period) and modest losses in abundance (−28.7–−10.2 individuals per route) that varied by migratory habit and nest location. Forest disturbance increased progressive similarity for Neotropical migrants, permanent residents, ground nesting, and cavity nesting species. We also documented highest progressive similarity in the eastern United States.

Conclusions/Significance

Contemporary forest bird community structure is changing rapidly over a relatively short period of time (e.g., ∼22 years). Forest disturbance and forest regeneration are primary factors associated with contemporary forest bird community structure, longitude and latitude are secondary factors, and forest loss is a tertiary factor. Importantly, these findings suggest some regions of the United States may already fall below the habitat amount threshold where fragmentation effects become important predictors of forest bird community structure.