Turnover of cell surface-bound capsular polysaccharide in Staphylococcus aureus

The capsular polysaccharide (CPS) of Staphylococcus aureus strain Smith was labelled by growth of bacteria in the presence of radioactive N-acetylglucosamine and was separated from labelled cell wall components by affinity chromatography on wheat germ agglutinin following dissolution of the cells by lysostaphin. The products were partially characterised chemically and immunochemically. Similar labelled components were found in the culture fluid during growth. In a pulse-chase experiment, cell-bound CPS was released continuously into the culture fluid at the same rate as cell wall turnover and there was no evidence of direct excretion of CPS.     

Cub growth and maternal care in cheetahs

Using cub growth as an index, I examine the influence of maternalnutrition, litter size, and cub sex on maternal care in cheetahs(Acinonyx jubatus) and compare cub and litter growth rates withthose of other large feilds. Seventy-nine free-living cheetahcubs in 21 litters from 15 mothers were weighed at least oncebetween 6 and 48 days of age. Eleven litters were weighed atthe beginning and end of a 5-day observation of their mothers.The mean cub growth rate varied significantly between litters,due primarily to differences in maternal food intake. Growthdeclined sharply when maternal food intake was less than 1.5kg/ day, but did not increase with greater levels of food intake.Lower limits of growth rates may therefore have been set bythe mother's food intake, whereas upper limits may be set bythe intrinsic physiological ability of cubs to grow. Althoughmale cubs were heavier than female cubs in the same litter whenfirst weighed, major differences in growth rate between thesexes were not apparent at this stage. Both cheetah cubs andlitters grow fast relative to other large felids, and I arguethat this may be an adaptation to the high rate of cheetah juvenilemortality from predation.     

Temperature gradient gel electrophoresis: detection of a single base substitution in the cattle β-lactoglobulin gene

An A in equilibrium with G transition in exon III is known to differentiate alleles A and B of the cattle beta-lactoglobulin (BLG) gene. A BLG exon III fragment containing the transition site was amplified by the polymerase chain reaction. Temperature gradient gel electrophoresis (TGGE) was then used to detect this transition and hence to genotype cattle: the AT base-pair in allele A was readily distinguished from the GC base-pair of allele B. TGGE can be used to detect any single base-pair substitution, and thus is a powerful method of detecting genetic variability.     

The structure and function of phytochrome A: the roles of the entire molecule and of its various parts

Phytochrome A is readily cleavable by proteolytic agents to yield an amino-terminal fragment of 66 kilodalton (kDa), which consists of residues 1 to approximately 600, and a dimer of the carboxy-terminal 55-kDa fragment, from residue 600 or so to the carboxyl terminus. The former domain, carrying the tetrapyrrole chromophore, has been studied extensively because of its photoactivity, while less attention has been paid to the non-chromophoric portion until quite recently. However, the evidence gathered to date suggests that this domain is also of great improtance. We present here a review of the structure and the biochemical and physiological functions of the two domains, of parts of these domains, and of the cooperation between them.     

Neuronal calcium signaling via store-operated channels in health and disease

Store-operated calcium entry (SOCE) is the flow of calcium ions (Ca²⁺) into cells in response to the depletion of intracellular Ca²⁺ stores that reside predominantly in the endoplasmic reticulum (ER). The role of SOCE has been relatively well understood for non-excitable cells. It is mediated mostly by the ER Ca²⁺ sensor STIM1 and plasma membrane Ca²⁺ channel Orai1 and serves to sustain Ca²⁺ signaling and refill ER Ca²⁺ stores. In contrast, because of the complexity of Ca²⁺ influx mechanisms that are present in excitable cells, our knowledge about the function of neuronal SOCE (nSOCE) is still nascent. This review summarizes the available data on the molecular components of nSOCE and their relevance to neuronal signaling. We also present evidence of disturbances of nSOCE in neurodegenerative diseases (namely Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease) and traumatic brain injury. The emerging important role of nSOCE in neuronal physiology and pathology makes it a possible clinical target.     

Conjugation of phosphonoacetic acid to nucleobase promotes a mechanism-based inhibition

Small molecule inhibitors have a powerful blocking action on viral polymerases. The bioavailability of the inhibitor, nevertheless, often raise a significant selectivity constraint and may substantially limit the efficacy of therapy. Phosphonoacetic acid has long been known to possess a restricted potential to block DNA biosynthesis. In order to achieve a better affinity, this compound has been linked with natural nucleotide at different positions. The structural context of the resulted conjugates has been found to be crucial for the acquisition by DNA polymerases. We show that nucleobase-conjugated phosphonoacetic acid is being accepted, but this alters the processivity of DNA polymerases. The data presented here not only provide a mechanistic rationale for a switch in the mode of DNA synthesis, but also highlight the nucleobase-targeted nucleotide functionalization as a route for enhancing the specificity of small molecule inhibitors.     

Metabolic Reconfiguration in C. elegans Suggests a Pathway for Widespread Sterol Auxotrophy in the Animal Kingdom

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Detecting early-warning signals for influenza A pandemic based on protein dynamical network biomarkers

The outbreak of influenza A comes from a relatively stable state is a critical phenomenon on epidemic. In this paper, influenza A varying from different states is studied in the method of dynamical network biomarkers (DNB). Through studying DNB of influenza A virus protein, we can detect the warning signals of outbreak for influenza A and obtain a composite index. The composite index varies along with the state of pandemic influenza, which gives a clue showing the turn point of outbreak. The low value (<1) steady state of the composite index means influenza A is normally in the relatively steady stage. Meanwhile, if the composite index of a certain year increases by more than 0.8 relative to the previous year and it is less than 1 and it increases sharply and reaches a peak being larger than 1 in next year, it means the year is normal in the critical state before outbreak and the next year is normally in the outbreak state. Therefore, we can predict the outbreak of influenza A and identify the critical state before influenza A outbreak or outbreak state by observing the variation of index value.