Splenectomy protects against sepsis lethality and reduces serum HMGB1 levels

High mobility group box 1 (HMGB1) is a critical mediator of lethal sepsis. Previously, we showed that apoptotic cells can activate macrophages to release HMGB1. During sepsis, apoptosis occurs primarily in lymphoid organs, including the spleen and thymus. Currently, it is unclear whether this accelerated lymphoid organ apoptosis contributes to systemic release of HMGB1 in sepsis. In this study, we report that splenectomy significantly reduces systemic HMGB1 release and improves survival in mice with polymicrobial sepsis. Treatment with a broad-spectrum caspase inhibitor reduces systemic lymphocyte apoptosis, suppresses circulating HMGB1 concentrations, and improves survival during polymicrobial sepsis, but fails to protect septic mice following splenectomy. These findings indicate that apoptosis in the spleen is essential to the pathogenesis of HMGB1-mediated sepsis lethality.     

High-Salinity-Induced Iron Limitation in Bacillus subtilis

Proteome analysis of Bacillus subtilis cells grown at low and high salinity revealed the induction of 16 protein spots and the repression of 2 protein spots, respectively. Most of these protein spots were identified by mass spectrometry. Four of the 16 high-salinity-induced proteins corresponded to DhbA, DhbB, DhbC, and DhbE, enzymes that are involved in the synthesis of 2,3-dihydroxybenzoate (DHB) and its modification and esterification to the iron siderophore bacillibactin. These proteins are encoded by the dhbACEBF operon, which is negatively controlled by the central iron regulatory protein Fur and is derepressed upon iron limitation. We found that iron limitation and high salinity derepressed dhb expression to a similar extent and that both led to the accumulation of comparable amounts of DHB in the culture supernatant. DHB production increased linearly with the degree of salinity of the growth medium but could still be reduced by an excess of iron. Such an excess of iron also partially reversed the growth defect exhibited by salt-stressed B. subtilis cultures. Taken together, these findings strongly suggest that B. subtilis cells grown at high salinity experience iron limitation. In support of this notion, we found that the expression of several genes and operons encoding putative iron uptake systems was increased upon salt stress. The unexpected finding that high-salinity stress has an iron limitation component might be of special ecophysiological importance for the growth of B. subtilis in natural settings, in which bioavailable iron is usually scarce.     

N-acetylmuramoyl-L-alanine amidase assay based on specific radioactive labeling of muropeptide L-alanine: quantitation of the enzyme activity in the autolysin deficient Bacillus subtilis 168, flaD strain.

A sensitive and highly reproducible assay for N-acetylmuramoyl-L-alanine amidase (EC 3.5.1.28) was devised, based on specific and homogeneous L-[14C]alanine labeling of the substrate, the peptidoglycan. The method involves partial purification of both the enzyme and the substrate and monitoring the muropeptide cleavage by coupling fluorodinitrobenzene to freed L-alanine NH2 groups. After acid hydrolysis of the substrate, the resulting DNP-L-alanine and L-alanine are separated by TLC, and radioactive counts in relevant spots are determined. Application of the method to the autolysin-endowed strain and an autolysis-deficient flaD-bearing mutant has revealed (i) that the N-acetylmuramoyl-L-alanine amidase behaves like an endoenzyme with an apparent Kcat(s-1) of 40, and (ii) that the residual enzyme activity in the flaD bearing strain amounts to 2.5 (+/- 0.1)% of that of the parent strain.     

Ciliary beating frequency of frog palate and rat trachea explants under continuous perfusion

Rat trachea and frog palate explants were continuously perfused for 2 hr with 199 tissue culture medium. The ciliary beating frequency of the frog palate exhibited fluctuations twice as large as compared to the rat trachea. The rat trachea model should be preferred to the frog palate for long-term studies on ciliary beat frequency.     

Scabies and Impetigo Prevalence and Risk Factors in Fiji: A National Survey

BackgroundScabies is recognised as a major public health problem in many countries, and is responsible for significant morbidity due to secondary bacterial infection of the skin causing impetigo, abscesses and cellulitis, that can in turn lead to serious systemic complications such as septicaemia, kidney disease and, potentially, rheumatic heart disease. Despite the apparent burden of disease in many countries, there have been few large-scale surveys of scabies prevalence or risk factors. We undertook a population-based survey in Fiji of scabies and impetigo to evaluate the magnitude of the problem and inform public health strategies.ConclusionsAs far as we are aware, this is the first national survey of scabies and impetigo ever conducted. We found that scabies occurs at high levels across all age groups, ethnicities, and geographical locations. Improved strategies are urgently needed to achieve control of scabies and its complications in endemic communities.     

Male mating preference of two cryptic species of the herbivorous insect Eccritotarsus catarinensis

When using biological control against pest populations, more than one biocontrol agent might be introduced simultaneously. This could be counterproductive in the event of negative interactions between the biocontrol agents. Within and between species interactions have a strong impact on mating behaviour and reproduction, and can have an impact on the effectiveness of biological control. We studied the reproductive compatibility between two geographically isolated strains (Brazil and Peru) of Eccritotarsus catarinensis (Heteroptera: Miridae), a biocontrol agent against the invasive aquatic weed, Eichhornia crassipes. By performing inter- and intra-species mating experiments, we investigated whether or not males from each of the cryptic species would be able to distinguish between partners from either species, and if they would mate with partners from the opposite species. Our results showed the decrease in lifetime fecundity, and most importantly, the lack of production of offspring from eggs resulting from forced hybridisation. We showed that Peruvian males mated only with females from their own species, and did not mate with females from the Brazilian species. In contrast, Brazilian males mated equally with females from both species, but needed significantly more time in order to commence a mating, and no offspring were produced from eggs resulting from hybridisation. Although future studies demand more rigorous controls, our results indicate asymmetrical sexual isolation between the two species. We speculate on mechanisms involved in reproductive isolation in the two cryptic species, and the possible implications for effective biocontrol, and include some morphological measurements that might support our assumptions.     

Impact of flower rewards on phytophagous insects: importance of pollen and nectar for the development of the pollen beetle (<Emphasis Type="Italic">Brassicogethes aeneus</Emphasis>)

Entomophilous plants reward pollinators with provision of nutrient-rich foods such as pollen and nectar. These rewards contain compounds that are essential to insect development and can be used by pollinators as well as herbivorous insects. The pollen beetle (Brassicogethes aeneus, syn. Meligethes aeneus) whose larvae develop in oilseed rape flowers (Brassica napus) is known to feed on pollen. Previous studies already showed the importance of pollen on the development of this insect but it seems that other resource, such as nectar, could also be used. The purpose of this study was to assess the respective roles of pollen and nectar on pollen beetle development. We tested their role with behavioural and developmental experiments using flowers where the presence and absence of nectar and pollen varied. Larvae, irrespective of their instar, fed both on anthers and nectar. Nectar did not influence larval development or adult survival while pollen influenced development by increasing both larval and adult weight. However, pollen did not affect larval or adult survival nor development time. These results indicate that pollen beetle larvae are adapted to deal with various diets and can complete their development without pollen or nectar.     

Studies on structure-function relationships of human choriogonadotropins with C-terminally shortened α-subunits. II. Stimulation of adenylate cyclase activity and depletion of cytochromeP-450 in the rat testis

Human choriogonadotropin (hCG) analogues, containing the native β-subunit and α-subunits enzymatically shortened by 2–3 amino acid residues, were used for studying influence of hCG on the content of microsomal progesterone-binding cytochromeP-450 in rat tests. When 2–3 residues have been renuwed from the α-subunit, the ability of the hormone analogue to stimulate adenylate cyclase of isolated rat Leydig cells was diminished by 55%. When the hCG analogue containing a des-(88–92)-α chain was applied, the residual activity of the adenylate cyclase was negligible. 18 h after administration to rats in vivo, the hormone species containing des-(Lys-91-Ser-92)-α or des-(90–92)-α, respectively, were found to have induced a decrease in microsomal cytochromeP-450 content with an effectiveness corresponding to their ability of stimulating the adenylate cyclase in vitro. However, when assayed 48 h after application, the desensitization of the microsomal cytochromeP-450 system had persisted in case of the hCG species containing a des-(90–92)-α chain but not in case of hCG consisting of des-(Lys-91-Ser-92)-α and a native β-subunit. From these results, it is concluded that short-term effects of hCG on the microsomal content of progesterone-binding cytochromeP-450 are mediated by the stimulation of adenylate cyclase. In contrast, the long-lasting action of hCG on this system seems not to be exclusively mediated by the increase in intracellular cAMP.     

<Emphasis Type="Italic">Fusarium equiseti</Emphasis> LPSC 1166 and its in vitro role in the decay of <Emphasis Type="Italic">Heterostachys ritteriana</Emphasis> leaf litter

The role of microorganisms in litter degradation in arid and semi-arid zones, where soil and water salinization is one of the main factors limiting carbon turnover and decay, remains obscure. Heterostachys ritteriana (Amaranthaceae), a halophyte shrub growing in arid environments such as “Salinas Grandes” (Córdoba, Argentina), appears to be the main source of organic matter in the area. Little is known regarding the microorganisms associated with H. ritteriana, although they are a potential source of enzymes such as cellulolytic ones, which might be important in biotechnological fields such as bioethanol production using ionic liquids. In the present study, by studying the microbiota growing on H. ritteriana leaf litter in “Salinas Grandes,” we isolated the cellulolytic fungus Fusarium equiseti LPSC 1166, which grew and degraded leaf litter under salt stress. The growth of this fungus was a function of the C substrate and the presence of NaCl. Although in vitro the fungus used both soluble and polymeric compounds from H. ritteriana litter and synthesized extracellular β-1,4 endoglucanases, its activity was reduced by 10% NaCl. Based on these results, F. equiseti LPSC 1166 can be described as a halotolerant cellulolytic fungus most probably playing a key role in the decay of H. ritteriana leaf litter in “Salinas Grandes.”