Plankton composition,biomass, phylogeny and toxin genes in Lake Big Momela,Tanzania

Lake Big Momela, one of the East African soda lakes in Northern Tanzania characterised by highly saline-alkaline conditions, making them inhospitable to a range of organisms, although supporting massive growths of some adapted planktonic microorganisms that serve as food for birds, such as Lesser Flamingo. The temporal dynamics of plankton, with an emphasis on cyanobacteria, were examined in 2007 using morphological traits and ribosomal genetic markers (16S and 18S rRNA). Cyanobacterial genes encoding for hepatotoxins (mcyE and ndaF) were also screened. Rotifers and copepods dominated the zooplankton, whereas cyanobacteria, such as Anabaenopsis elenkinii and Arthrospira fusiformis dominated the phytoplankton community, and these being related to representatives in other East African soda lakes. The cyanobacteria community also showed distinct seasonal patterns influenced by environmental parameters, mainly salinity, pH and nitrate. Significant positive correlations were found between phytoplankton abundance and nitrate concentrations (r = 0.617, p = 0.033). No signals of the hepatotoxin synthetase genes mcyE and ndaF were retrieved from cyanobacteria during the whole year. In general, our data illustrate the presence of rich planktonic communities, including some unique and potentially endemic cyanobacteria.     

Identification of genes encoding exported Mycobacterium tuberculosis proteins using a Tn552'phoA in vitro transposition system

Secreted and cell envelope-associated proteins are important to both Mycobacterium tuberculosis pathogenesis and the generation of protective immunity to M. tuberculosis. We used an in vitro Tn552'phoA transposition system to identify exported proteins of M. tuberculosis. The system is simple and efficient, and the transposon inserts randomly into target DNA. M. tuberculosis genomic libraries were targeted with Tn552'phoA transposons, and these libraries were screened in M. smegmatis for active PhoA translational fusions. Thirty-two different M. tuberculosis open reading frames were identified; eight contain standard signal peptides, six contain lipoprotein signal peptides, and seventeen contain one or more transmembrane domains. Four of these proteins had not yet been assigned as exported proteins in the M. tuberculosis databases. This collection of exported proteins includes factors that are known to participate in the immune response of M. tuberculosis and proteins with homologies, suggesting a role in pathogenesis. Nine of the proteins appear to be unique to mycobacteria and represent promising candidates for factors that participate in protective immunity and virulence. This technology of creating comprehensive fusion libraries should be applicable to other organisms.     

Value of a newly sequenced bacterial genome

Next-generation sequencing(NGS) technologies have made high-throughput sequencing available to medium- and small-size laboratories, culminating in a tidal wave of genomic information. The quantity of sequenced bacterial genomes has not only brought excitement to the field of genomics but also heightened expectations that NGS would boost antibacterial discovery and vaccine development. Although many possible drug and vaccine targets have been discovered, the success rate of genome-based analysis has remained below expectations. Furthermore, NGS has had consequences for genome quality, resulting in an exponential increase in draft(partial data) genome deposits in public databases. If no further interests are expressed for a particular bacterial genome, it is more likely that the sequencing of its genome will be limited to a draft stage, and the painstaking tasks of completing the sequencing of its genome and annotation will not be undertaken. It is important to know what is lost when we settle for a draft genome and to determine the "scientific value" of a newly sequenced genome. This review addresses the expected impact of newly sequenced genomes on antibacterial discovery and vaccinology. Also, it discusses the factors that could be leading to the increase in the number of draft deposits and the consequent loss of relevant biological information.     

Fatty acid composition of the depot fats of the Polynesian rat,Rattus exulans,Tokelau Islands

The fatty acid composition of the stomach contents, adipose tissue, and perinephric fat of Polynesian rats (Rattus exulans Peale), from the Tokelau Is indicated that the dietary fat consisted mainly, if not exclusively, of coconut oil. Lower ratios of lauric : myristic acids were found in the depot fats of the Polynesian rats than in the dietary coconut oil. These results were consistent with chain elongation of lauric to myristic acid after ingestion, as previously reported in rats and other mammals.     

Waikanae River estuary: Changes to habitat and bird fauna evident from surveys thirty years apart

Abstract

A second ecological survey of the Waikanae estuary, in the North Island of New Zealand, was carried out 30 years after the first (1941–1943), and was of similar duration. The observer for the first survey participated in the second, and the same methods were used. Brief accounts are given of the prevailing climate and geology, and of physical changes at the estuary. The effect of periodic storms and of the various encroachments by man is recorded; the latter appear to be particularly important. The vegetation of the estuary is described. Records of beach patrols and of other ornithologists supplement the authors' observations on the bird life. The numbers of birds recorded in the two surveys are compared by analyses of variance. Changes in the flora deduced from aerial photographs spanning the two surveys and from notes and photographs are related to man-induced disturbance, natural physical changes, and natural succession. The total of 79 bird species recorded at the estuary and in its immediate vicinity compares favourably with the 60 species recorded during the first survey. The increase of nearly one-third is due to such factors as the appearance of new Australian bird species, the information provided by the beach patrols, and the extension of sand-flat habitat. In terms of numbers observed, 10 bird species have increased, 11 remain unchanged, and 8 have declined. The distribution of birds is considered in relation to nine areas of habitat: the beach and open sea; open dunes at the beach front; river and sand flats; unfixed and fixed dunes; saltmarsh; grassed fields; and lakelets. The most species (29) were recorded on sand flats and the least (7) on unfixed dunes. Periodic rechannelling of the river mouth has led to expansion of the sand flats as a habitat for waders and some other shore birds, but other man-induced developments, such as housing, are threatening the present ecological balance of the estuary. Use of the area for recreation and for wildlife study is increasing, and we consider that action by conservation authorities is urgently required.     

ORGANIZATION AND BREAKDOWN OF THE PROTOPLAST DURING MATURATION OF PINE TRACHEIDS

The protoplast of maturing axial tracheids in the secondary xylem of shortleaf pine (Pinus echinata Mill.) was studied by transmission and scanning electron microscopy. The mature protoplast is differentiated into two interconnected components: (1) the commonly observed peripheral layer lining the secondary cell wall, and (2) an elaborate reticulum of cytoplasmic filaments and placoids within the central vacuole. The reticulum provides an extensive surface area of vacuolar membranes for rapid exchange of nutrients and metabolites with the vacuolar sap, which is envisaged to function as a vital medium during the period of secondary cell wall synthesis. The breakdown of the protoplast which terminates tracheid maturation is associated with poorly defined alterations of the vacuolar membranes. This is indicated by increased formation of cytoplasmic spherules and membraneous vesicles which may be portions of separated vacuolar membrane during early stages of degradation. Autolysis is supposed to occur when the cytoplasm is exposed to the vacuolar sap after rupture and separation of the vacuolar membranes. The Gomori acid phosphatase technique as combined with electron microscopy produced no evidence of autolysosomal segresomes in strands of intravacuolar reticulum of the cytoplasm.     

Chlormadinone acetate and its effect on the hemostatic mechanism

There is an apparent discrepancy between the effects on the hemostatic mechanism of synthetic progestins alone and synthetic progestins in combination with synthetic estrogens. Coagulation studies were carried out on 21 patients treated with chlormadinone acetate 0.5 mg. on a continuous daily basis for 12 weeks in order to determine its effects on hemostasis. Unlike the standard estrogen/progestin contraceptive agents, this synthetic progestin appears to have no effect on the coagulation system as determined by standard laboratory tests.     

Ectoparasites from fruit bats and rats on Niue Island

Examination of 3 species of mammals from Niue Island revealed the following host/ectoparasite associations. Rattus rattus (L.) : the mites Androlaelaps casalis, Laelaps echidninus, L. nuttalli, Ornithonyssus bacoti, Listrophoroides cucullatus, and Dermatophagoides pteronys‐sinus; and the louse Polyplax spinulosa. Rattus exulans (Peale) : L. echidninus, L. nuttali, and L. cucullatus; and the louse Hoplopleura pacifica. Pteropus t. tonganus Quoy & Gaimard: the mite Meristaspis calcarata. These new records for the island are discussed in relation to existing records from the Pacific region.