Evolution of late-life mortality in Drosophila melanogaster

Abstract.— Aging appears to cease at late ages, when mortality rates roughly plateau in large-scale demographic studies. This anomalous plateau in late-life mortality has been explained theoretically in two ways: (1) as a strictly demographic result of heterogeneity in life-long robustness between individuals within cohorts, and (2) as an evolutionary result of the plateau in the force of natural selection after the end of reproduction. Here we test the latter theory using cohorts of Drosophila melanogaster cultured with different ages of reproduction for many generations. We show in two independent comparisons that populations that evolve with early truncation of reproduction exhibit earlier onset of mortality-rate plateaus, in conformity with evolutionary theory. In addition, we test two population genetic mechanisms that may be involved in the evolution of late-life mortality: mutation accumulation and antagonistic pleiotropy. We test mutation accumulation by crossing genetically divergent, yet demographically identical, populations, testing for hybrid vigor between the hybrid and nonhybrid parental populations. We found no difference between the hybrid and nonhybrid populations in late-life mortality rates, a result that does not support mutation accumulation as a genetic mechanism for late-life mortality, assuming mutations act recessively. Finally, we test antagonistic pleiotropy by returning replicate populations to a much earlier age of last reproduction for a short evolutionary time, testing for a rapid indirect response of late-life mortality rates. The positive results from this test support antagonistic pleiotropy as a genetic mechanism for the evolution of late-life mortality. Together these experiments comprise the first corroborations of the evolutionary theory of late-life mortality.     

Proteasome-associated cysteine deubiquitinases are molecular targets of environmental optical brightener compounds

The levels of organic pollutants, such as optical brightener (OB) compounds, in the global environment have been increasing in recent years. The toxicological effects and signal transduction systems associated with OB toxicity have not been thoroughly studied. The ubiquitin-proteasome system (UPS) plays a crucial role in regulating multiple essential cellular processes, and proteasome-associated cysteine deubiquitinases (DUBs), ubiquitin C-terminal hydrolase L5 (UCHL5) and USP14, are two major regulators for (de)ubiquitination and stability of many important target proteins. Therefore, potential inhibition of UCHL5 and USP14 activities by some environmental chemicals might cause in vivo toxicity. In the current study we hypothesize that electrophilic OB compounds, such as 4,4′-diamino-2,2′-stilbenedisulfonic acid(DAST), fluorescent brightener 28 (FB-28) and FB-71, can interact with the catalytic triads (CYS, HIS, and ASP) of UCHL5 and USP14 and inhibit their enzymatic activities, leading to cell growth suppression. This hypothesis is supported by our findings presented in this study. Results from in silico computational docking and ubiquitin vinyl sulfone assay confirmed the UCHL5/USP14-inhibitory activities of these OB compounds that have potencies in an order of: FB-71 > FB-28 > DAST. Furthermore, inhibition of these two proteasomal DUBs by OBs resulted in cell growth inhibition and apoptosis induction in two human breast cancer cell models. In addition, we found that OB-mediated DUB inhibition triggers a feedback reaction in which expression of UCHL5 and USP14 proteins is increased to compromise the suppressed activities. Our study suggests that these commonly used OB compounds may target and inhibit proteasomal cysteine DUBs, which should contribute to their toxicological effects in vivo.     

Ultrasonic monitoring of early-stage biofilm growth on polymeric surfaces

Biofilm growth on polymeric surfaces was monitored using ultrasonic frequency-domain reflectometry (UFDR). The materials utilized for this study included nonporous polycarbonate (PC) sheets, polyamide (PA) nanofiltration composite membranes and porous polyvinylidene fluoride (PVDF) microfiltration membranes (nominal pore size: 0.65 microm). Coupons of each material were placed in a biologically active annular reactor for up to 300 days, and subjected to a constant shear field (0.12 N m(-2)), which induced sessile microbial growth from acetate amended municipal tap water. Acoustic monitoring was non-destructively executed by traversing coupons in a constant temperature water bath using a spherically focused 20-MHz immersion transducer. This semi-automated system was configured to obtain reflections from 50 regions (c.a. 120x10(3) microm2) distributed evenly near the centerline of each coupon. The resulting reflected power distributions were compared with standard biochemical and microscopic assays that described surface associated biofilms. When compared to clean (virgin) conditions, biofilms growing on coupons induced consistent attenuations in reflection amplitude, which caused statistically significant shifts in reflected power (p<0.01). Using exocellular polysaccharides as a surrogate measure of total biofilm mass, UFDR was able to detect biofilms developing on any of the materials tested at surface-averaged masses < or = 150 microg cm(-2). Above these threshold levels, increasing amounts of exocellular polysaccharides correlated with significant decreases in total reflected power (TRP). The distribution of biomass on the coupon surfaces determined by acoustic spectra was consistent with that observed using environmental scanning electron microscopy (ESEM). These results suggest that UFDR may be used as a non-destructive tool to monitor biofouling in a wide variety of applications.     

A Sunken Ship of the Desert at the River Danube in Tulln,Austria

Rescue excavations recovered a skeleton that resurrect the contemporary dramatic history of Austria in the 17^th century as troops besieged Vienna in the second Osmanic-Habsburg war. Unique for Central Europe is the evidence of a completely preserved camel skeleton uncovered in a large refuse pit. The male individual of slender stature indicates a few but characteristic pathological changes revealing not a beast of burden but probably a valuable riding animal. Anatomical and morphometrical analyses suggest a hybrid confirmed by the ancient DNA analyses resulting in the presence of a dromedary in the maternal and a Bactrian camel in the paternal line.     

Survival rate of preantral follicles derived from vitrified neonate mouse ovarian tissue by Cryotop and conventional methods

The aim of this study was to investigate the growth and survival rate of preantral follicles isolated from vitrified ovarian tissue by Cryotop and conventional methods. The ovaries of 14-day-old mice were separated and divided into four groups as following: Cryotop group, vitrified by Cryotop; CV (Conventional; CV) group, vitrified by conventional straw; toxicity test group and control group. After warming the vitrified ovaries, isolated preantral follicles from four groups were cultured for 4 days to compare survival rate and follicular growth between above-mentioned groups. Survival rate (97.3%) in toxicity test group alike the control group (98.7%) were significantly higher (P<0.05) than the Cryotop (92.7%) and CV (47.7%) groups. Increase in follicle diameters after 4 days in Cryotop and CV groups was significantly lower (P<0.05) than the control and toxicity test groups, but growth and survival rate of follicles in Cryotop group was significantly higher (P<0.05) than the CV group. These results demonstrated that ovarian tissue vitrification by Cryotop highly preserves the viability rate of preantral follicles.     

Lateralization in monogamous pairs:wild geese prefer to keep their partner in the left hemifield except when disturbed

Behavioural lateralization, which reflects the functional specializations of the two brain hemispheres, is assumed to play an important role in cooperative intraspecific interactions. However, there are few studies focused on the lateralization in cooperative behaviours of individuals, especially in a natural setting. In the present study, we investigated lateralized spatial interactions between the partners in life-long monogamous pairs. The male-female pairs of two geese species (barnacle, Branta leucopsis, and white-fronted, Anser albifrons geese), were observed during different stages of the annual cycle in a variety of conditions. In geese flocks, we recorded which visual hemifield (left/right) the following partner used to monitor the leading partner relevant to the type of behaviour and the disturbance factors. In a significant majority of pairs, the following bird viewed the leading partner with the left eye during routine behaviours such as resting and feeding in undisturbed conditions. This behavioural lateralization, implicating the right hemisphere processing, was consistent across the different aggregation sites and years of the study. In contrast, no significant bias was found in a variety of geese behaviours associated with enhanced disturbance (when alert on water, flying or fleeing away when disturbed, feeding during the hunting period, in urban area feeding and during moulting). We hypothesize that the increased demands for right hemisphere processing to deal with stressful and emergency situations may interfere with the manifestation of lateralization in social interactions.     

Effect of low-level laser therapy on experimental wounds of hard palate mucosa in mice

Under general anesthesia and sterile conditions, incision wound was induced in the hard palate mucosa of adult male mice. The wounds of groups 1 and 2 were irradiated daily with He-Ne laser at 3 and 7.5 J/cm2 for 120 and 300 s, respectively, while the incision wound of group 3 not exposed served as controls. On day 3 of injury, the laser-treated wounds contained significantly lower neutrophils than the wounds in the control group. By day 7 after injury, the laser-treated wounds contained significantly more fibroblasts and at the same time contained significantly fewer macrophages. In conclusion, an acceleration of the wound healing process of experimental wounds in the hard palate mucosa of mice at low-level laser therapy with a He-Ne laser at energy densities of 3 and 7.5 J/cm2 was observed.     

Conformational Flexibility Determines Selectivity and Antibacterial, Antiplasmodial, and Anticancer Potency of Cationic ��-Helical Peptides

We used a combination of fluorescence, circular dichroism (CD), and NMR spectroscopies in conjunction with size exclusion chromatography to help rationalize the relative antibacterial, antiplasmodial, and cytotoxic activities of a series of proline-free and proline-containing model antimicrobial peptides (AMPs) in terms of their structural properties. When compared with proline-free analogs, proline-containing peptides had greater activity against Gram-negative bacteria, two mammalian cancer cell lines, and intraerythrocytic Plasmodium falciparum, which they were capable of killing without causing hemolysis. In contrast, incorporation of proline did not have a consistent effect on peptide activity against Mycobacterium tuberculosis. In membrane-mimicking environments, structures with high α-helix content were adopted by both proline-free and proline-containing peptides. In solution, AMPs generally adopted disordered structures unless their sequences comprised more hydrophobic amino acids or until coordinating phosphate ions were added. Proline-containing peptides resisted ordering induced by either method. The roles of the angle subtended by positively charged amino acids and the positioning of the proline residues were also investigated. Careful positioning of proline residues in AMP sequences is required to enable the peptide to resist ordering and maintain optimal antibacterial activity, whereas varying the angle subtended by positively charged amino acids can attenuate hemolytic potential albeit with a modest reduction in potency. Maintaining conformational flexibility improves AMP potency and selectivity toward bacterial, plasmodial, and cancerous cells while enabling the targeting of intracellular pathogens.     

Hippocampal and Cortical Primary Cilia Are Required for Aversive Memory in Mice

It has been known for decades that neurons throughout the brain possess solitary, immotile, microtubule based appendages called primary cilia. Only recently have studies tried to address the functions of these cilia and our current understanding remains poor. To determine if neuronal cilia have a role in behavior we specifically disrupted ciliogenesis in the cortex and hippocampus of mice through conditional deletion of the Intraflagellar Transport 88 (Ift88) gene. The effects on learning and memory were analyzed using both Morris Water Maze and fear conditioning paradigms. In comparison to wild type controls, cilia mutants displayed deficits in aversive learning and memory and novel object recognition. Furthermore, hippocampal neurons from mutants displayed an altered paired-pulse response, suggesting that loss of IFT88 can alter synaptic properties. A variety of other behavioral tests showed no significant differences between conditional cilia mutants and controls. This type of conditional allele approach could be used to distinguish which behavioral features of ciliopathies arise due to defects in neural development and which result from altered cell physiology. Ultimately, this could lead to an improved understanding of the basis for the cognitive deficits associated with human cilia disorders such as Bardet-Biedl syndrome, and possibly more common ailments including depression and schizophrenia.