The cell cycle associated protein, HTm4, is expressed in differentiating cellsof the hematopoietic and central nervous system in mice

HTm4 is a member of a newly defined family of human and murine proteins, the MS4 (membrane-spanning four) protein group, which has a distinctive four-transmembrane structure. MS4 protein functions include roles as cell surface signaling receptors and intracellular adapter proteins. We have previously demonstrated that HTm4 regulates the function of the KAP phosphatase, a key regulator of cell cycle progression. In humans, the expression of HTm4 is largely restricted to cells of the hematopoietic lineage, possibly reflecting a causal role for this molecule in differentiation/proliferation of hematopoietic lineage cells. In this study, we show that, like the human homologue, murine HTm4 is also predominantly a hematopoietic protein with distinctive expression patterns in developing murine embryos and in adult animals. In addition, we observed that murine HTm4 is highly expressed in the developing and adult murine nervous system, suggesting a previously unrecognized role in central and peripheral nervous system development.JLK and XY contributed equally to this work     

A mitochondrial protein, Bit1, mediates apoptosis regulated by integrins and Groucho/TLE corepressors

A delicate balance of signals regulates cell survival. One set of these signals is derived from integrin-mediated cell adhesion to the extracellular matrix (ECM). Loss of cell attachment to the ECM causes apoptosis, a process known as anoikis. In searching for proteins involved in cell adhesion-dependent regulation of anoikis, we identified Bit1, a mitochondrial protein that is released into the cytoplasm during apoptosis. Cytoplasmic Bit1 forms a complex with AES, a small Groucho/transducin-like enhancer of split (TLE) protein, and induces cell death with characteristics of caspase-independent apoptosis. Cell attachment to fibronectin counteracts the apoptotic effect of Bit1 and AES. Increasing Bit1 expression enhances anoikis, while suppressing the expression reduces it. Thus, we have elucidated an integrin-controlled pathway that is, at least in part, responsible for the cell survival effects of cell-ECM interactions.     

Collateral sprouting occurs following end-to-side neurorrhaphy

Recent evidence supports the use of end-to-side neurorrhaphy for the treatment of certain peripheral nerve disorders. However, the mechanism by which nerves regenerate following this procedure is still unclear. To address this question, the authors designed a new end-to-side coaptation model in rats in which the donor nerves were uninjured. The regenerated axons at the coaptation site were observed directly using fluorescent dye as the neural tracer. The sciatic nerve from adult Wistar rats was transplanted between the left and right median nerves. Fifteen rats were divided into three groups. In group I, the donor (right median) nerve was sutured end to side to the divided grafted nerve using a noninjury technique. In group II, the aponeurosis of the spinal muscles was harvested and the sciatic and right median nerves were coapted end to side noninjuriously by wrapping them in the excised aponeurosis. In group III, a perineurial window was created and a partial neurectomy was carried out at the suture site, after which the sciatic and right median nerves were sutured end to side. Sixty days after the operation, nerve regeneration was evaluated by recording action potentials in the grafted nerve, by performing electromyography in the flexor muscles in the forearm, and by histological examination. The grafted nerves were fixed and sectioned, the number of regenerated nerve fibers was counted, and axonal diameters were measured. Fluorescent dye crystal was used, in conjunction with confocal microscopy, to observe the regenerated axons at the co-aptation site. The results showed that nerve regeneration had occurred in the animals, as determined electrophysiologically and histologically. Both the right and left flexor muscles of the forearm contracted simultaneously as a result of indirect electric stimulation of the grafted nerve, which suggests that the regenerated nerve was physiologically connected with the donor nerve. Nerve fiber counts did not show any differences among groups (p > 0.05), but axonal diameters were significantly greater in group III than in the other two groups. Fluorescent dye staining revealed the presence of regenerated nerve fibers beyond the coaptation site. In group III, the regenerating nerves were observed within the whole section of the coaptation site and collateral sprouting was found to occur even at a site distal to the suture. From these results, the authors conclude that in end-to-side neurorrhaphy, nerve regeneration occurs by collateral sprouting from the donor nerve.     

Occurrence of D-histidine residues in antimicrobial poly(arginyl-histidine), conferring resistance to enzymatic hydrolysis

The antimicrobial peptide poly(arginyl-histidine) is secreted by the ergot fungus Verticillium kibiense. We previously showed that poly(arginyl-histidine) from the fungus inhibits the growth of certain microorganisms more effectively than that chemically synthesized from the L-form of arginine and histidine, implying some substantial differences between the fungal and synthetic peptides. To elucidate what causes such differences, we here investigated the structural features of the fungal peptides. The acid hydrolysates of the fungal peptide contained d-histidine. When synthetic poly(L-arginyl-D-histidine) mimicking the fungal peptide was added to the culture of Salmonella typhimurium together with poly(L-arginyl-L-histidine), poly(L-arginyl-D-histidine) was not easily degraded during the incubation compared with poly(L-arginyl-L-histidine). We concluded that the d-form of histidine residues in the fungal peptide prolongs the life of the peptide leading to the enhancement of antimicrobial activity.     

Spatial distribution and seasonal changes of pesticides in Lake Biwa,Japan

The spatial distribution and seasonal variation in the concentrations in Lake Biwa of pesticides used in paddy fields were studied. Lake Biwa is the largest lake in Japan and is a recognized water resource for 14 million people in the Kinki district. Samples were collected nine times from April to December 2001 at ten sites within the lake and at the mouths of six influent rivers. Weekly sampling was also carried out at a single site on an effluent river. Among the 20 pesticides analyzed, the detection frequencies in surface water were almost 100% for simetryn, bromobutide, and isoprothiolane; around 75% for molinate and pyroquilon; around 30% for three herbicides and one fungicide; and almost zero for the remaining substances. The maximum concentrations of pesticides detected frequently in the lake were in the range 0.1–0.4µgl^–1. The occurrence of a few pesticides below the thermocline may be explained by thermal stratification and vertical circulation. Although the thermocline suppressed vertical diffusion in spring and summer during pesticide application periods, a few pesticides remaining at the surface of the lake in winter were transported to the hypolimnion by vertical circulation and remained there even after the reestablishment of the thermocline. The half-lives of pesticides in the lake were estimated to be more than a year for simetryn, half a year for bromobutide, 1.5 months for molinate, and 1 month for dimepiperate. The main cause of elimination for molinate and dimepiperate was estimated to be degradation, that for simetryn was outflow, and for bromobutide both degradation and outflow were significant.     

Calcium dependence of native metabotropic glutamate receptor signaling in central neurons

Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors that are distributed throughout the brain and play important roles in regulation of synaptic efficacy. Some studies report that mGluRs heterologously expressed in nonneuronal cells are sensitive not only to glutamate but also to extracellular Ca²⁺ (Ca _o ²⁺ ). We studied the Ca _o ²⁺ -sensitivity of native mGluRs in mammalian central neurons. In cerebellar Purkinje cells that naturally express type-1 mGluR (mGluR1), physiological levels of Ca _o ²⁺ (around 2 mM) activate mGluR1-mediated intracellular Ca²⁺ mobilization. The activation of the native mGluR1 response to Ca _o ²⁺ appears to be slower than that to glutamate. Ca _o ²⁺ (2 mM) also augments glutamate analog-evoked, native mGluR1-mediated inward cation current and intracellular Ca _o ²⁺ mobilization. Detailed analysis of this effect suggests that Ca _o ²⁺ modulates the glutamate responsiveness of native and heterologously expressed mGluR1s in different manners. These findings suggest that Ca _o ²⁺ may enhance the basal level and glutamate responsiveness of neuronal mGluR signaling in vivo.     

Multigene family for Bowman-Birk type proteinase inhibitors of wild soja and soybean: the presence of two BBI-A genes and pseudogenes

Genes for Bowman-Birk type protease inhibitors (BBIs) of wild soja (Glycine soja) and soybean (Glycine max) comprise a multigene family. The organization of the genes for wild soja BBIs (wBBIs) was elucidated by an analysis of their cDNAs and the corresponding genomic sequences, and compared with the counterparts in the soybean. The cDNAs encoding three types of wild soja BBIs (wBBI-A, -C, and -D) were cloned. Two subtypes of cDNAs for wBBI-A, designated wBBI-A1 and -A2, were further identified. Similar subtypes (sBBI-A1 and -A2) were also found in the soybean genome. cDNA sequences for wBBIs were highly homologous to those for the respective soybean homologs. Phylogenetic analysis of these cDNAs demonstrated the evolutional proximity between these two leguminae strains.