DNA polymerase β is critical for mouse meiotic synapsis

We have shown earlier that DNA polymerase β (Pol β) localizes to the synaptonemal complex (SC) during Prophase I of meiosis in mice. Pol β localizes to synapsed axes during zygonema and pachynema, and it associates with the ends of bivalents during late pachynema and diplonema. To test whether these localization patterns reflect a function for Pol β in recombination and/or synapsis, we used conditional gene targeting to delete the PolB gene from germ cells. We find that Pol β-deficient spermatocytes are defective in meiotic chromosome synapsis and undergo apoptosis during Prophase I. We also find that SPO11-dependent γH2AX persists on meiotic chromatin, indicating that Pol β is critical for the repair of SPO11-induced double-strand breaks (DSBs). Pol β-deficient spermatocytes yielded reduced steady-state levels of the SPO11-oligonucleotide complexes that are formed when SPO11 is removed from the ends of DSBs, and cytological experiments revealed that chromosome-associated foci of replication protein A (RPA), RAD51 and DMC1 are less abundant in Pol β-deficient spermatocyte nuclei. Localization of Pol β to meiotic chromosomes requires the formation of SPO11-dependent DSBs. Taken together, these findings strongly indicate that Pol β is required at a very early step in the processing of meiotic DSBs, at or before the removal of SPO11 from DSB ends and the generation of the 3′ single-stranded tails necessary for subsequent strand exchange. The chromosome synapsis defects and Prophase I apoptosis of Pol β-deficient spermatocytes are likely a direct consequence of these recombination defects.     

Dominant inheritance and intra�Cfamilial variations in the association of Sturge�CWeber and Klippel�CTrenaunay�CWeber syndromes

This case report shows a genealogical study where a woman has limb hypertrophy and her son has an association of Sturge–Weber syndrome with Klippel–Trenaunay–Weber syndrome. The Sturge–Weber and Klippel–Trenaunay–Weber syndromes appear to be different manifestations of the same affliction. Familial aggregation exists and transmission may be almost imperceptible between generations. Identification of minor manifestations may prove to be a valuable contribution to genetic counseling of families and the prevention of new cases.     

A peptide of glutamic acid decarboxylase 65 can recruit and expand a diabetogenic T cell clone, BDC2.5, in the pancreas

Self peptide-MHC ligands create and maintain the mature T cell repertoire by positive selection in the thymus and by homeostatic proliferation in the periphery. A low affinity/avidity interaction among T cells, self peptides, and MHC molecules has been suggested for these events, but it remains unknown whether or how this self-interaction is involved in tolerance and/or autoimmunity. Several lines of evidence implicate the glutamic acid decarboxylase 65 (GAD-65) peptide, p524-543, as a specific, possibly low affinity, stimulus for the spontaneously arising, diabetogenic T cell clone BDC2.5. Interestingly, BDC2.5 T cells, which normally are unresponsive to p524-543 stimulation, react to the peptide when provided with splenic APC obtained from mice immunized with the same peptide, p524-543, but not, for example, with hen egg white lysozyme. Immunization with p524-543 increases the susceptibility of the NOD mice to type 1 diabetes induced by the adoptive transfer of BDC2.5 T cells. In addition, very few CFSE-labeled BDC2.5 T cells divide in the recipient's pancreas after transfer into a transgenic mouse that overexpresses GAD-65 in B cells, whereas they divide vigorously in the pancreas of normal NOD recipients. A special relationship between the BDC2.5 clone and the GAD-65 molecule is further demonstrated by generation of a double-transgenic mouse line carrying both the BDC2.5 TCR and GAD-65 transgenes, in which a significant reduction of BDC2.5 cells in the pancreas has been observed, presumably due to tolerance induction. These data suggest that unique and/or altered processing of self Ags may play an essential role in the development and expansion of autoreactive T cells.     

裂解性弧菌噬菌体的分离及生理特性

[目的]弧菌是水产养殖生物中常见的病原菌,本研究旨在寻求水产养殖病害可能的生物防治途径.[方法]本文于2006年春季、2005年秋季从沿岸海水及淡水湖采样,通过"双层平板法"分离裂解性弧菌噬菌体;对噬菌体及宿主进行电镜形态观测,同时采用16S rDNA分子测序技术鉴定宿主,并对噬菌体进行生理特性测定.[结果]从10个样品中分离出96株弧菌、2株裂解性噬菌体(Vibrio/XM/P1、Vibrio/XM/P2),噬菌体宿主分别属于Vibrio alginolyticus(溶澡弧菌)和Vibrio anguillarum(鳗弧菌);噬菌体头部都呈六边形,Vibrio/XM/P2有尾;两株噬菌体活性最适pH分别为7、8,最适温度分别为25℃、30℃,并都对高温和紫外线敏感;Vibrio/XM/P1对乙醚、氯仿不敏感,Vibrio/XM/P2对乙醚、氯仿敏感.     

Osteopathy may decrease obstructive apnea in infants: a pilot study

Background

Obstructive apnea is a sleep disorder characterized by pauses in breathing during sleep: breathing is interrupted by a physical block to airflow despite effort. The purpose of this study was to test if osteopathy could influence the incidence of obstructive apnea during sleep in infants.

Methods

Thirty-four healthy infants (age: 1.5–4.0 months) were recruited and randomized in two groups; six infants dropped out. The osteopathy treatment group (n = 15 infants) received 2 osteopathic treatments in a period of 2 weeks and a control group (n = 13 infants) received 2 non-specific treatments in the same period of time. The main outcome measure was the change in the number of obstructive apneas measured during an 8-hour polysomnographic recording before and after the two treatment sessions.

Results

The results of the second polysomnographic recordings showed a significant decrease in the number of obstructive apneas in the osteopathy group (p = 0.01, Wilcoxon test), in comparison to the control group showing only a trend suggesting a gradual physiologic decrease of obstructive apneas. However, the difference in the decline of obstructive apneas between the groups after treatment was not significant (p = 0.43).

Conclusion

Osteopathy may have a positive influence on the incidence of obstructive apneas during sleep in infants with a previous history of obstructive apneas as measured by polysomnography. Additional research in this area appears warranted.     

Activity-related changes of body fat and motor performance in obese seven-year-old boys

The effects of 35 weeks of extra-curricular, mainly aerobic, dynamic physical activity were analysed in overweight and obese 7-year-old boys contrasted with control groups. Body composition was estimated by using the body mass index (BMI) and skinfold thicknesses. Overweight or obesity was defined according to the suggestions of Cole and associates (2000). The activity program consisted of swimming and water games, folk dance, and soccer. Data were collected four times between September 2003 and October 2004. Thirty-one overnight or obese boys volunteered to participate in the activity program (weekly, to physical classes of 45 min. plus three extra-curricular activity sessions of 60 min. duration). The control subjects were 43 overweight or obese boys, and 75 non-overweight and non-obese ones. The controls had only two curricular physical education classes every week. Physical performance capacity was tested by 30 m dash, 400 m run, standing long jump, and fist-ball throw. Body fat content estimated by taking the sum of five skinfolds decreased significantly during the 35-week training program. However, body weight as well as skinfold thicknesses increased significantly during the four month non-active period that followed. Physical performance improved during the test period, but deteriorated between the third and fourth data collections. BMI, as well as the sum of five skinfolds increased in both control groups.Physical performance decreased in the overweight control subjects and increased moderately in the non obese ones. We inferred that more vigorous habitual exercise alone, i.e., without a program of dietary control, though effective, could not efficiently stabilise body fat, still less achieve a lasting reduction of it. Obese, but also overweight subjects need long term exercise programs of sufficient intensity, duration and frequency, plus dietary measures, to get rid of excess body fat.     

Role of amphiphysin II in somatostatin receptor trafficking in neuroendocrine cells

Amphiphysins are SH3 domain-containing proteins thought to function in clathrin-mediated endocytosis. To investigate the potential role of amphiphysin II in cellular trafficking of G protein-coupled somatostatin (SRIF) receptors, we generated an AtT-20 cell line stably overexpressing amphiphysin IIb, a splice variant that does not bind clathrin. Endocytosis of (125)I-[d-Trp(8)]SRIF was not affected by amphiphysin IIb overexpression. However, the maximal binding capacity (B(max)) of the ligand on intact cells was significantly lower in amphiphysin IIb overexpressing than in non-transfected cells. This difference was no longer apparent when the experiments were performed on crude cell homogenates, suggesting that amphiphysin IIb overexpression interferes with SRIF receptor targeting to the cell surface and not with receptor synthesis. Accordingly, immunofluorescence experiments demonstrated that, in amphiphysin overexpressing cells, sst(2A) and sst(5) receptors were segregated in a juxtanuclear compartment identified as the trans-Golgi network. Amphiphysin IIb overexpression had no effect on corticotrophin-releasing factor 41-stimulated adrenocorticotropic hormone secretion, suggesting that it is not involved in the regulated secretory pathway. Taken together, these results suggest that amphiphysin II is not necessary for SRIF receptor endocytosis but is critical for its constitutive targeting to the plasma membrane. Therefore, amphiphysin IIb may be an important component of the constitutive secretory pathway.     

A family of brevinin-2 peptides with potent activity against Pseudomonas aeruginosa from the skin of the Hokkaido frog, Rana pirica

Nine peptides displaying varying degrees of antimicrobial activity were extracted from the skin of the Hokkaido frog, Rana pirica. Five structurally related peptides were identified as members of the brevinin-2 family. These peptides were active against reference strains of Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella pneumoniae) and Gram-positive (Staphlococcus aureus) bacteria but displayed relatively low hemolytic activity. The most abundant peptide, brevinin-2PRa (680 nmol/g weight of dry skin) showed high potency [minimal inhibitory concentration (MIC) values between 6 and 12 microM] against a range of clinical isolates of P. aeruginosa. In addition, activity was unaffected by NaCl concentrations up to 200 mM. Cladistic analysis based on the primary structures of brevinin-2 peptides supports a close phylogenetic relationship between R. pirica and Japanese mountain brown frog Rana ornativentris. One peptide of the ranatuerin-2 family and one strongly hemolytic peptide of the brevinin-1 family were also isolated from the extract along with two members of the temporin family, temporin-1PRa (ILPILGNLLNGLL.NH(2)) and temporin-1PRb (ILPILGNLLNSLL.NH(2)) that atypically lacked basic amino acid residues and showed only very weak antimicrobial and hemolytic activity.     

Central role of the threonine residue within the p+1 loop of receptor tyrosine kinase in STAT3 constitutive phosphorylation in metastatic cancer cells

The receptor tyrosine kinases (RTKs) RET, MET, and RON all carry the Met(p+1loop)-->Thr point mutation (i.e., 2B mutation), leading to the formation of tumors with high metastatic potential. Utilizing a novel antibody array, we identified constitutive phosphorylation of STAT3 in cells expressing the 2B mutation but not wild-type RET. MET or RON with the 2B mutation also constitutively phosphorylated STAT3. Members of the EPH, the only group of wild-type RTK that carry Thr(p+1loop) residue, are often expressed unexpectedly in different types of cancers. Ectopic expression of wild-type but not Thr(p+1loop)-->Met substituted EPH family members constitutively phosphorylated STAT3. In both RTK(Metp+1loop) with 2B mutation and wild-type EPH members the Thr(p+1loop) residue is required for constitutive kinase autophosphorylation and STAT3 recruitment. In multiple endocrine neoplasia 2B (MEN-2B) patients expressing RET(M918T), nuclear enrichment of STAT3 and elevated expression of CXCR4 was detected in metastatic thyroid C-cell carcinoma in the liver. In breast adenocarcinoma cell lines expressing multiple EPH members, STAT3 constitutively bound to the promoters of MUC1, MUC4, and MUC5B genes. Inhibiting STAT3 expression resulted in reduced expression of these metastasis-related genes and inhibited mobility. These findings provide insight into Thr(p+1loop) residue in RTK autophosphorylation and constitutive activation of STAT3 in metastatic cancer cells.