Exploration Behavior and Morphology are Correlated in Captive Gray Mouse Lemurs (<Emphasis Type="Italic">Microcebus murinus</Emphasis>)

Behavior varies among individuals and is flexible within individuals. However, studies of behavioral syndromes and animal personality have demonstrated that animals can show consistency in their behavior and as such may be restricted in their behavioral responses. Like any other trait, including morphology, performance, or physiology, personality is now considered an important component of ecology and may have fitness consequences. Moreover, in some species personality correlates with other traits, as predicted in the context of a recent theoretical framework postulating that individual differences in growth and body size can affect behavior through effects on growth–mortality tradeoffs. This “pace of life” hypothesis predicts that animals that explore more should be larger and have higher growth rates than those that explore less. We tested for associations between morphology and a behavioral trait in a captive colony of gray mouse lemurs (Microcebus murinus). We used open-field tests to evaluate exploration behavior and measured a series of morphological traits in 72 individuals (32 males and 40 females). Our results show that the latency to start exploring correlates positively with adult body size and body weight at birth. These data provide evidence for a link between morphology and behavior in this species, thus supporting predictions of dispersal models but diverging from the predictions of the “pace of life” model.     

Coupling between taxonomic and functional diversity in protistan coastal communities

The study of protistan functional diversity is crucial to understand the dynamics of oceanic ecological processes. We combined the metabarcoding data of various coastal ecosystems and a newly developed trait-based approach to study the link between taxonomic and functional diversity across marine protistan communities of different size-classes. Environmental DNA was extracted and the V4 18S rDNA genomic region was amplified and sequenced. In parallel, we tried to annotate the operational taxonomic units (OTUs) from our metabarcoding dataset to 30 biological traits using published and accessible information on protists. We then developed a method to study trait correlations across protists (i.e. trade-offs) in order to build the best functional groups. Based on the annotated OTUs and our functional groups, we demonstrated that the functional diversity of marine protist communities varied in parallel with their taxonomic diversity. The coupling between functional and taxonomic diversity was conserved across different protist size classes. However, the smallest size-fraction was characterized by wider taxonomic and functional groups diversity, corroborating the idea that nanoplankton and picoplankton are part of a more stable ecological background on which larger protists and metazoans might develop.     

A Surface-Induced Asymmetric Program Promotes Tissue Colonization by Pseudomonas aeruginosa

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Dynamics of magnetotactic bacteria in a rotating magnetic field

The dynamics of the motile magnetotactic bacterium Magnetospirillum gryphiswaldense in a rotating magnetic field is investigated experimentally and analyzed by a theoretical model. These elongated bacteria are propelled by single flagella at each bacterial end and contain a magnetic filament formed by a linear assembly of approximately 40 ferromagnetic nanoparticles. The movements of the bacteria in suspension are analyzed by consideration of the orientation of their magnetic dipoles in the field, the hydrodynamic resistance of the bacteria, and the propulsive force of the flagella. Several novel features found in experiments include a velocity reversal during motion in the rotating field and an interesting diffusive wandering of the trajectory curvature centers. A new method to measure the magnetic moment of an individual bacterium is proposed based on the theory developed.     

A basic peptide derived from the HARP C-terminus inhibits anchorage-independent growth of DU145 prostate cancer cells

Heparin affin regulatory peptide (HARP) is an 18 kDa heparin-binding protein that plays a key role in tumor growth. We showed previously that the synthetic peptide P(111-136) composed of the last 26 HARP amino acids inhibited HARP-induced mitogenesis. Here, to identify the exact molecular domain involved in HARP inhibition, we investigated the effect of the shorter basic peptide P(122-131) on DU145 cells, which express HARP and its receptor protein tyrosine phosphatase beta/zeta (RPTPbeta/zeta). P(122-131) was not cytotoxic; it dose-dependently inhibited anchorage-independent growth of DU145 cells. Binding studies using biotinylated P(122-131) indicated that this peptide interfered with HARP binding to DU145 cells. Investigation of the mechanisms involved suggested interference, under anchorage-independent conditions, of P(122-131) with a HARP autocrine loop in an RPTPbeta/zeta-dependent fashion. Thus, P(122-131) may hold potential for the treatment of disorders involving RPTPbeta/zeta.     

PaTrx1 and PaTrx3, two cytosolic thioredoxins of the filamentous ascomycete Podospora anserina involved in sexual development and cell degeneration

In various organisms, thioredoxins are known to be involved in the reduction of protein disulfide bonds and in protecting the cell from oxidative stress. Genes encoding thioredoxins were found by searching the complete genome sequence of the filamentous ascomycete Podospora anserina. Among them, PaTrx1, PaTrx2, and PaTrx3 are predicted to be canonical cytosolic proteins without additional domains. Targeted disruption of PaTrx1, PaTrx2, and PaTrx3 shows that PaTrx1 is the major thioredoxin involved in sulfur metabolism. Deletions have no effect on peroxide resistance; however, data show that either PaTrx1 or PaTrx3 is necessary for sexual reproduction and for the development of the crippled growth cell degeneration (CG), processes that also required the PaMpk1 mitogen-activated protein kinase (MAPK) pathway. Since PaTrx1 PaTrx3 mutants show not an enhancement but rather an impairment in CG, it seems unlikely that PaTrx1 and PaTrx3 thioredoxins participate in the inhibition of this MAPK pathway. Altogether, these results underscore a role for thioredoxins in fungal development.     

Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity

RecQ helicases are essential for the maintenance of chromosome stability. In addition to DNA unwinding, some RecQ enzymes have an intrinsic DNA strand annealing activity. The function of this dual enzymatic activity and the mechanism that regulates it is, however, unknown. Here, we describe two quaternary forms of the human RECQ1 helicase, higher-order oligomers consistent with pentamers or hexamers, and smaller oligomers consistent with monomers or dimers. Size exclusion chromatography and transmission electron microscopy show that the equilibrium between the two assembly states is affected by single-stranded DNA (ssDNA) and ATP binding, where ATP or ATPγS favors the smaller oligomeric form. Our three-dimensional electron microscopy reconstructions of human RECQ1 reveal a complex cage-like structure of approximately 120 Å × 130 Å with a central pore. This oligomeric structure is stabilized under conditions in which RECQ1 is proficient in strand annealing. In contrast, competition experiments with the ATPase-deficient K119R and E220Q mutants indicate that RECQ1 monomers, or tight binding dimers, are required for DNA unwinding. Collectively, our findings suggest that higher-order oligomers are associated with DNA strand annealing, and lower-order oligomers with DNA unwinding.     

The ion channel,TRPM2, contributes to the pathogenesis of radiodermatitis

Radiation and Environmental Biophysics - Radiodermatitis is a painful side effect for cancer patients undergoing radiotherapy. Irradiation of the skin causes inflammation and breakdown of the...     

Isozyme evidence for three sibling species in the Anopheles sundaicus complex from Indonesia

Electrophoretic studies of isoenzymes in three chromosomally distinct forms (A, B and C) of the mosquito Anopheles sundaicus Theobald (Diptera: Culiciae) were undertaken on wild samples collected from six geographically isolated populations in Indonesia. Analyses of 12 enzyme systems comprising 15 loci revealed significant allelic variations, genetic polymorphism, within and among the populations of the An. sundaicus complex. Phylogenetic dendrograms produced by analysis using the Biosys-1 program based on UPGMA methods show that all the populations of form A fall into one cluster, which is closely related to the form C cluster, whereas the populations of form B belong to a more distinct cluster. Allelic frequency and Wright's F statistics of Mpi (mannose phosphate isomerase) are sufficient to identify individuals of each cytological form. This isozyme data correlates with our previous cytological evidence for the existence of three isomorphic species within the taxon An. sundaicus in Indonesia. These three species of the An. sundaicus complex were found together sympatrically at one locality, Asahan in North Sumatra.