Comparative in vivo and in vitro analyses of putative virulence factors of Burkholderia pseudomallei using lipopolysaccharide, capsule and flagellin mutants

Burkholderia pseudomallei is a gram-negative bacillus that is the causative agent of melioidosis. We evaluated host–pathogen interaction at different levels using three separate B. pseudomallei mutants generated by insertional inactivation. One of these mutants is defective in the production of the polysaccharide side chains associated with lipopolysaccharide; one does not produce the capsular polysaccharide with the structure -3)-2- O -acetyl-6-deoxy-β- d - manno -heptopyranose-(1-; and the third mutant does not produce flagellin. We compared the in vivo virulence in BALB/c mice, the in vitro fate of intracellular survival inside human polymorphonuclear cells (PMNs) and macrophages (Mφs) and the susceptibility to killing by 30% normal human serum, reactive nitrogen and oxygen intermediates and antimicrobial peptides with that of their wild-type counterpart. The lipopolysaccharide and capsule mutants demonstrated a marked reduction in virulence for BALB/c mice, but the flagellin mutant was only slightly less virulent than the parent strain. The results from the BALB/c mice experiments correlated with survival in Mφs. The lipopolysaccharide and capsule mutants were also more susceptible to killing by antimicrobial agents. All bacteria were equally susceptible to killing by PMNs. Altogether, the data suggest that lipopolysaccharide and capsule and, to a much lesser extent, flagella, are most likely associated with the virulence of this bacterium and highlight the importance of intracellular killing by PMNs and Mφs in disease pathogenesis.     

Fine structure of the mammalian renal capsule: The atypical smooth muscle cell and its functional meaning

Summary The present electron microscopic study on the fine structure of the renal capsule of some mammals (mouse, rat, mole, guinea pig and rabbit) shows that, although there are some variations in the structure, the general morphology is the same.The renal capsule of these animals consists of two layers, a connective tissue layer and an atypical smooth muscle cell layer, and is bound to the renal parenchyma by a thin peritubular loose connective tissue. The atypical smooth muscle cell is characterized by the existence of fine cytoplasmic filaments usually arranged along the long axis of the cell, and the cells also show a complicated interlocking among adjacent cells. The atypical smooth muscle cells gradually undergo a transition to fibroblasts of the upper connective tissue layer, losing their similarities to smooth muscle cells.When intrarenal pressure is elevated and the renal capsule is distended, the intercellular space among interdigitating or overlapping atypical smooth muscle cells is extensively dilated.Tracers such as horseradish peroxidase and ferritin injected intravenously or intraperitoneally can transverse the renal capsule.From the present study, it is concluded that the renal capsule of mammals possesses common structures, and contains atypical smooth muscle cells. These morphological characteristics suggest that the renal capsule could play a certain role related to the renal function.The author wishes to acknowledge the helpful advices of Prof. T. Yamamoto     

Observations on the production of purple pigments in the egg capsules,hypobranchial and reproductive glands from seven species of Muricidae (Gastropoda: Mollusca)

Summary

Tyrian purple is a well-known colourant that can be obtained from the hypobranchial glands of muricids. Here we investigate the presence of purple and related pigments in the hypobranchial glands, reproductive glands and egg capsules of three Rapaninae, three Ocenebrinae and one Muricinae species. Observations on the dissected specimens revealed the presence of purple pigmentation in the hypobranchial glands of all species. All of the Rapaninae and the Muricinae, but only some species of Ocenebrinae, appear to transfer the pigment precursors to their egg capsules. This provides evidence that the precursors of Tyrian purple are not produced for the sole purpose of protecting the egg masses as has been previously suggested. In all the subfamilies, the hypobranchial and reproductive (capsule and prostate) glands lie adjacent to one another. Colour changes in the reproductive glands, indicating the presence of dye precursors, were observed in two species of Rapaninae. In Dicathais orbita, colour changes could be seen in both the capsule glands of females and prostrate glands of males. The final colour was more red in the reproductive glands than the purple observed in the hypobranchial glands. Preliminary observations of detached hypobranchial gland sections in both D. orbita and Pterynotus triformis indicate a different suite of colour reactions occur when compared to sections that are intact and attached to the reproductive glands. This demonstrates that the reproductive glands can influence the chemical conversions of dye precursors synthesized by these species. Further studies on the secondary metabolism occurring within the hypobranchial glands and reproductive organs of Muricidae are ongoing, including histological sectioning and confirmation of the chemistry behind the colours observed and functional analysis of Tyrian purple precursors.     

Bound morphine and codeine in the capsule of Papaver somniferum

The polysaccharide fraction of the capsule of Papaver somniferum contained bound morphine and codeine. The alkaloids appear to be bound to the polymer by two different types of linkage.     

Pericapsular smooth muscle cells in renal corpuscles of the Mongolian gerbil

Summary During the course of a systematic investigation of the renal corpuscles in various desert rodents (Meriones unguiculati, Meriones shawii, Psammomys obesus, and Dipodymis), a thickened Bowman's capsule was observed light microscopically in some kidneys of adult Meriones unguiculati (Mongolian gerbil). Electron microscopic studies show that this unusual finding may depend on the presence of one or two layers of typical smooth muscle cells adjacent to the outer surface of the basal lamina. In the kidneys of other species of desert rats examined, no pericapsular smooth muscle cells were observed.     

Genetic determinants of host tropism in Klebsiella phages

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Length-weight relationships of four predatory stonefly species in Japan

Estimates of biomass are essential for studies modeling the structure, animal growth, production, and energy flow in ecosystems. The relationships between dry weight and head capsule width or body length in summer and winter were examined for four species of predatory stonefly (Perlidae) nymphs in Japan. There were some variations in regression constants between seasons and species. However, the distribution of length-weight plots did not show marked differences between species or season. Our results suggest that length-weight relationship data, regardless of season or including multiple species, are also valid for estimation of dry weight when the target species are classified into the same taxonomic family.