Covalent linkage of polyamines to peptidoglycan in Anaerovibrio lipolytica

Spermidine and cadaverine were found to be constituents of the cell wall peptidoglycan of Anaerovibrio lipolytica, a strictly anaerobic bacterium. The peptidoglycan was degraded with the N-acetylmuramyl-L-alanine amidase and endopeptidase into two peptide fragments, peptide I and peptide II, at a molar ratio of 4:1. Peptides I and II were identified as L-alanine-D-glutamic acid(alphacadaverine)gammameso-diaminopimelic acid (DAP)-D-alanine and L-alanine-D-glutamic acid(alphaspermidine)gammameso-DAP-D-alanine, respectively. The N(1)-amino group of spermidine was linked to the alpha-carboxyl group of the D-glutamic acid residue of peptide II.     

Pitcher plant facilitates prey capture in a sympatric congener

Carnivorous plants avoid below-ground competition for nitrogen by utilizing an alternative nitrogen resource—invertebrate prey, but it remains unclear if sympatric carnivorous plants compete for prey resources. The aim of this study was to investigate if exploitative prey-resource competition occurs between the two sympatric pitcher plant species, Nepenthes rafflesiana and N. gracilis in Singapore. We first investigated if prey-resource partitioning occurs between these two species, and then investigated niche shift in N. gracilis by examining its pitcher contents along an in situ gradient of N. rafflesiana interspecific competition. Our results showed clear evidence of resource partitioning between the two species, but contrary to the expectation of competition, proximity to N. rafflesiana pitchers correlated with higher total prey numbers in N. gracilis pitchers. Our multivariate model of prey assemblages further suggested that N. rafflesiana facilitates N. gracilis prey capture, especially in several ant taxa that are trapped by both species. Concurrently, we found strong evidence for intraspecific competition between N. gracilis pitchers, suggesting that prey resources are exhaustible by pitcher-predation. Our results show that resource partitioning can be associated with facilitative interactions, instead of competition as is usually assumed. Facilitation is more typically expected between phylogenetically distant species, but divergences in resource acquisition strategies can permit facilitation between congeners.     

Severely reduced production of klotho in human chronic renal failure kidney

We recently identified a novel gene, termed klotho (kl) that is involved in the development of a syndrome in mice resembling human aging. A defect of the kl gene expression in mice leads to multiple disorders including arteriosclerosis, osteoporosis, ectopic calcification, and skin atrophy together with short life-span and infertility. Patients with chronic renal failure (CRF), develop multiple complications that are reminiscent of phenotypes observed in kl mutant mice. Furthermore, the kl gene is mainly expressed in kidney and brain. These evidences above suggest the possible involvement of Klotho function in the complications arising in CRF patients. To investigate the above possibility, we examined the kidneys of 10 clinically or histologically diagnosed CRF cases. The level of kl gene expression was measured by utilizing RNase protection assay. The expression of Klotho protein was assayed by utilizing Western blot analysis and by immunohistochemistry. The levels of kl mRNA expression were greatly reduced in all CRF kidneys. Moreover, the production of Klotho protein was also severely reduced in all CRF kidneys. These results suggest that the decrease in kl gene expression in CRF patients may underlie the deteriorating process of multiple complications in the CRF patients.     

Chondrosarcoma of the proximal femur with myxoid degeneration mistaken for chondromyxoid fibroma in a young adult. A case report

BACKGROUND: Fine needle aspiration cytology (FNAC) is effective in the diagnosis of bone tumors when combined with careful radiologic and clinical evaluation. However, cases where clinical or radiologic findings are atypical or unusual may lead to an erroneous diagnosis. CASE: A 19-year-old male presented with a pain in the left hip area that had been slowly progressive over a 10-month period. Clinical and radiologic findings suggested either giant cell tumor or chondroblastoma. The smeared aspiration specimen showed loosely cohesive, oval to round cells with moderate amounts of pale pink cytoplasm admixed with pinkish-blue, chondromyxoid material. The individual cells contained a single nucleus with evenly distributed, fine chromatin. A few osteoclastic giant cells were scattered in the smears. A cytologic diagnosis of myxoid lesion with a few giant cells, suspicious for chondromyxoid fibroma, was made. The diagnosis of chondrosarcoma was made by subsequent histologic examination. CONCLUSION: Absence of the usual clinicoradiologic features of chondrosarcoma combined with an unusual cytologic presentation in this case led to a misdiagnosis. In most centers, FNAC has achieved undisputed status as a diagnostic tool, and cytologic diagnosis often forms the basis of the therapeutic protocol. However, at some sites FNAC diagnosis is more problematic. Awareness of the limitations and pitfalls of FNAC is just as important as knowledge of the scope of FNAC in bone tumors. Tumors with chondromyxoid features provide particular difficulties.     

Identification of the amino acid residues conferring substrate specificity upon Selenomonas ruminantium lysine decarboxylase

Lysine decarboxylase (LDC, EC 4.1.1.18) from Selenomonas ruminantium has decarboxylating activities towards both L-lysine and L-ornithine with similar K(m) and Vmax. Here, we identified four amino acid residues that confer substrate specificity upon S. ruminantium LDC and that are located in its catalytic domain. We have succeeded in converting S. ruminantium LDC to an enzyme with a preference in decarboxylating activity for L-ornithine when the four-residue of LDC were replaced by the corresponding residues of mouse ornithine decarboxylase (EC 4.1.1.17).     

Construction of a LukS-PV mutant of a staphylococcal Panton-Valentine leukocidin component having a high LukS-like function

A 2-residue (D12I13) segment of LukS of a staphylococcal leukocidin component is an essential region for the hemolytic function of LukS towards rabbit erythrocytes in the presence of LukF. Here, we report that insertion of D, I, or AA residue(s) between A11 and E12 residues of LukS-PV, in which the 2-residue D12I13 segment in LukS was absent, confers the full LukS function on LukS-PV, which has only 4% hemolytic activity of that of LukS towards rabbit erythrocytes.