A Route to Direct Fitness: Natural and Experimentally Induced Queen Succession in the Tropical Primitively Eusocial Wasp <Emphasis Type="Italic">Ropalidia marginata</Emphasis>

Insect societies are hallmarks of cooperation because one or a few queens monopolize reproduction and several non-reproductive workers cooperatively raise brood. However, the loss of the queen exposes a colony to potential reproductive conflict, which is resolved only after a new queen takes over. We studied queen succession in natural and experimental colonies of the primitively eusocial wasp Ropalidia marginata to understand the proximate behavioral strategies involved in the resolution of this conflict. Previous work has shown that in this species, experimental queen removal always results in only one worker becoming hyper-aggressive and taking over the colony as its next queen, without ever being challenged. Here we show that even during natural queen turnover, one and only one worker becomes hyper-aggressive and takes over as the next queen, without being challenged. During natural queen turn-over, aggression of the successor may sometimes begin before the loss of the old queen and may sometimes decline more rapidly, unlike in the case of experimental queen removal. The successor begins to lay eggs sooner after a natural queen turn-over as compared to experimental queen removal. This is expected because workers might detect the gradual decline of the queen preceding her disappearance. Because queen succession is expected to be more prevalent in tropical perennial species, we expect natural selection to have favored such an orderly queen succession so that a route to direct fitness is available without significant reduction in cooperation.     

Neutron crystallographic studies of T4 lysozyme at cryogenic temperature

Bacteriophage T4 lysozyme (T4L) has been used as a paradigm for seminal biophysical studies on protein structure, dynamics, and stability. Approximately 700 mutants of this protein and their respective complexes have been characterized by X‐ray crystallography; however, despite the high resolution diffraction limits attained in several studies, no hydrogen atoms were reported being visualized in the electron density maps. To address this, a 2.2 Å‐resolution neutron data set was collected at 80 K from a crystal of perdeuterated T4L pseudo‐wild type. We describe a near complete atomic structure of T4L, which includes the positions of 1737 hydrogen atoms determined by neutron crystallography. The cryogenic neutron model reveals explicit detail of the hydrogen bonding interactions in the protein, in addition to the protonation states of several important residues.     

SAC and Berberine Mediated Repression of Reactive Species and Hepatoprotection After DEN + CCl<Subscript>4</Subscript> Exposure

Oxidative stress is proposed to play a pivotal role in the development of hepatocellular carcinoma. With an accelerated metabolism cancer cells demand high reactive species accumulation to maintain their indiscriminate cell growth and proliferation. Here we wanted to see the status of reactive species in the chemically induced liver cancer. For this purpose swiss albino mice were exposed to DEN and CCl₄ to develop an in vivo model of hepatocarcinoma. Depletion of cellular antioxidants regulated accretion of reactive species during the development of DEN + CCl₄ induced tumor formation in hepatocytes. Currently available therapeutics for heptatocellular carcinoma is costly and coupled with certain bystander effects to the surrounding control cells. Therefore considering the antioxidant properties of SAC and berberine we treated DEN + CCl₄ exposed mice after the development of liver tumor. Results effectively pointed out the usefulness of the alternative treatment with SAC and berberine in hepatoprotection. Replenishment of both enzymatic and non enzymatic antioxidant efficiently reduced accumulation of reactive species and that eventually closely associated with effective reduction in tumor number and size after drug treatment in DEN + CCl₄ exposed mice.     

Antimicrobial protein from Streptomyces fulvissimus inhibitory to methicillin resistant Staphylococcus aureus

Fermented culture of Streptomyces fulvissimus was found to secrete an antibacterial protein inhibitory to Micrococcus luteus, Bacillus subtilis, Bacillus cereus and methicillin resistant Staphylococcus aureus (MRSA) strains. The extracellular protein from the fermented culture on concentration revealed a high molecular weight peptide of 63kDa on SDS-PAGE gel and the region on gel displayed inhibitory activity against methicillin resistant Staphylococcus aureus. Bioactivity of the extra cellular protein was non-sensitive to proteinase K, alpha chymotrypsin, protease, EDTA (ethylene diamine tetra acetic acid), PMSF (phenyl methyl sulfonyl fluoride) and DMSO (dimethyl sulfoxide) but partially susceptible to amylase and heat. Glycoprotein nature of the proteinaceous compound was confirmed by periodic acid schiffs (PAS) staining. The secretary protein of S. fulvissimus demonstrated a significant activity against MRSA strain. It could be an important source for developing new drugs to control multidrug resistant gram positive bacteria.     

Nonuniform strain of human soleus aponeurosis-tendon complex during submaximal voluntary contractions in vivo.

The distribution of strain along the soleus aponeurosis tendon was examined during voluntary contractions in vivo. Eight subjects performed cyclic isometric contractions (20 and 40% of maximal voluntary contraction). Displacement and strain in the apparent Achilles tendon and in the aponeurosis were calculated from cine phase-contrast magnetic resonance images acquired with a field of view of 32 cm. The apparent Achilles tendon lengthened 2.8 and 4.7% in 20 and 40% maximal voluntary contraction, respectively. The midregion of the aponeurosis, below the gastrocnemius insertion, lengthened 1.2 and 2.2%, but the distal aponeurosis shortened 2.1 and 2.5%, respectively. There was considerable variation in the three-dimensional anatomy of the aponeurosis and muscle-tendon junction. We suggest that the nonuniformity in aponeurosis strain within an individual was due to the presence of active and passive motor units along the length of the muscle, causing variable force along the measurement site. Force transmission along intrasoleus connective tissue may also be a significant source of nonuniform strain in the aponeurosis.     

Highly specific gene silencing by artificial microRNAs in the unicellular alga Chlamydomonas reinhardtii

MicroRNAs (miRNAs) are small RNAs, 21 to 22 nucleotides long, with important regulatory roles. They are processed from longer RNA molecules with imperfectly matched foldback regions and they function in modulating the stability and translation of mRNA. Recently, we and others have demonstrated that the unicellular alga Chlamydomonas reinhardtii , like diverse multicellular organisms, contains miRNAs. These RNAs resemble the miRNAs of land plants in that they direct site-specific cleavage of target mRNA with miRNA-complementary motifs and, presumably, act as regulatory molecules in growth and development. Utilizing these findings we have developed a novel artificial miRNA system based on ligation of DNA oligonucleotides that can be used for specific high-throughput gene silencing in green algae.     

Discovery of GlyT1 inhibitors with improved pharmacokinetic properties

Glycine transporter 1 (GlyT1) represents a novel target for the treatment of schizophrenia via the potentiation of glutamatergic NMDA receptors. The discovery of 4,4-disubstituted piperidine inhibitors of GlyT1 which exhibit improved pharmacokinetic properties, including oral bioavailability, is discussed.     

Molecular mechanisms of experience-dependent plasticity in visual cortex

A remarkable amount of our current knowledge of mechanisms underlying experience-dependent plasticity during cortical development comes from study of the mammalian visual cortex. Recent advances in high-resolution cellular imaging, combined with genetic manipulations in mice, novel fluorescent recombinant probes, and large-scale screens of gene expression, have revealed multiple molecular mechanisms that underlie structural and functional plasticity in visual cortex. We situate these mechanisms in the context of a new conceptual framework of feed-forward and feedback regulation for understanding how neurons of the visual cortex reorganize their connections in response to changes in sensory inputs. Such conceptual advances have important implications for understanding not only normal development but also pathological conditions that afflict the central nervous system.