Background matters: the effects of estrogen receptor alpha gene disruption on male sexual behavior are modified by background strain

One approach to study interactions between behavior and genetics is to use inbred mice with different genetic backgrounds. To examine the effect of background on a specific gene, we conducted a series of experiments with a well-characterized knockout (KO) mouse, the estrogen receptor alpha KO (ERalphaKO). The ERalphaKO mouse has so far been examined in one inbred line, C57BL/6J. Here, we examined the behavior of ERalphaKO mice within three different backgrounds mixed with C57BL/6J; DBA/2J, BALB/c, and A/J. First, we assessed masculine sexual behavior in both intact male and testosterone-treated female offspring. More ERalphaKO males in the DBA/2J (5/12) and BALB/c (5/13) backcrosses displayed intromissions and many ejaculated as compared with males in a C57BL/6J and A/J mixed background. Many fewer ERalphaKO females than males displayed masculine sexual behavior in any of the three hybrid crosses. We assessed fertility in males from the C57BL/6J by DBA/2J cross and found that one of 12 ERalphaKO males sired a litter. Several other characteristics of sexual behavior and physiology were unaffected by genetic background in ERalphaKO mice. Our data suggest that genetic background has dramatic effects on male sexual behavior and its dependence on the ERalpha gene.     

Epitope scanning reveals gain and loss of strain specific antibody binding epitopes associated with the conversion of normal cellular prion to scrapie prion

We used anti-prion (PrP) monoclonal antibodies (Mabs) in different combinations to scan changes in the availability of antibody binding epitopes--using an epitope scanning assay--in brain homogenates from normal mice, and from mice infected with either ME7 or 139 A strains of infectious scrapie prion (PrPSc). In ME7-infected brains, the epitope detected by the Mab pair 8B4/8H4 is reduced, while the epitope detected by the Mab pair 8F9/11G5 is increased. Mab 8F9/11G5 detect a conformational epitope on PrPSc because the rise in Mab 8F9/11G5 binding is sensitive to a denaturing agent but resistant to proteinase K (PK). While the increase in Mab 8F9/11G5 binding correlates with the presence of PK-resistant PrP and clinical signs of infection, the reduction in Mab 8B4/8H4 binding is detected earlier. Fractionation of the ME7-infected brain homogenate in sucrose gradient revealed that the PrPSc species detected by the epitope scanning assay are heterogeneous in size, with a molecular mass of approximately > or = 2000-kDa. We also investigated whether these findings were applicable to two other strains of PrPSc, namely 87 V and 22 L. We found that the decrease in Mab 8B4/8H4 binding detected in ME7-infected brains was also detected in 87 V-infected brains but not in 22 L-infected brains. In contrast, the increase in Mab 8F9/11G5 binding detected in ME7- and 139 A-infected brains was also detected in 22 L-infected brains but not in 87 V-infected brains. Therefore, each prion strain has its unique conformation, and we can monitor the conversion of normal cellular prion (PrPC) to PrPSc based on the changes in the antibody binding patterns. The epitope can be decreased or increased, linear or conformational, detected late or early during infection, in a strain specific manner.     

几个引进枣品种枣头及果实生长发育规律的研究

研究得知湘南地区引进沾化冬枣、梨枣和骏枣的枣头一次枝(下简称枣头)伸长生长节律与本地品种鸡蛋枣相似,幼树期枣头有两次明显的伸长生长过程,其间出现生长暂缓期。从枣头年生长量看,三个引进品种均比本地品种鸡蛋枣要小,但秋季生长量比重均比鸡蛋枣还要大。三个引进品种果实均较鸡蛋枣大,果实生长规律均与鸡蛋枣相似。但各个品种果实生育期均长于鸡蛋枣。冬枣果实生育期最长为100天~110天,梨枣与骏枣果实生育较短,梨枣70天~75天,骏枣约85天,而鸡蛋枣只有65天~70天。     

Cryptococcus neoformans population includes hybrid strains homozygous at mating-type locus

Recent attempts to characterise the hybrid strains of Cryptococcus neoformans have led to the identification of a cryptic population of hybrid strains ('H strains') with double DNA content but only a single mating-type allele. To verify a set of hypotheses concerning their origin, we investigated 14 previously isolated H strains and ten F1-progeny strains arising from H99 and JEC20 mating. The double DNA content was tested by flow cytometry; the presence of only one mating type was tested by amplifying 12 mating-type-specific genes and one gene unlinked with the mating-type locus (URA5). Analysis of the F1 progeny identified two H strains, and electrophoretic karyotyping confirmed the occurrence of genetic recombination. The simultaneous presence of the homozygous and heterozygous loci, and the fact that all of the F1-progeny strains presented a recombinant karyotype, suggest that the H strains originated from the post-meiotic random fusion of two of the four recombinant nuclei. Further studies are required to elucidate the role of the homozygous mating-type loci in the virulence of C. neoformans.     

Virulence-defective strains of Salmonella enterica serovar Typhi as candidates for education at level 2 facilities

The use of biosafety level 3 pathogens is an essential element of education and training at medical schools. We previously reported on invasion-defective strains of Salmonella enterica serovar Typhi, GTC 3P408 (DeltainvA, DeltasipB) and GTC 3P409 (DeltainvA, DeltasipB, and DeltaviaB), as candidates for use in educational programs. Vi negative strains of S. enterica serovar Typhi became extremely sensitive to complement attack but showed increased invasiveness. Therefore, this study was conducted to construct two virulencedefective strains, GTC 3P460 (DeltainvA, DeltasipB, and DeltarpoS) and GTC 3P461 (DeltainvA, DeltasipB, DeltaviaB, and DeltarpoS), of S. enterica serovar Typhi by deleting rpoS from the GTC 3P409 and GTC 3P408 strains. Stress tests demonstrated that GTC 3P460 and GTC 3P461 are sensitive to conditions of starvation, acid stress and oxidative stress. These results suggest that these virulence-defective strains have difficulty surviving in the gastric environment and in macrophages, characteristics that make them ideal candidates for education at level 2 facilities. Colony morphology and conventional biochemical features of these strains are identical to the parent strain S. enterica serovar Typhi GIFU 10007.     

Involvement of the serotonergic cerebral system in microwave-induced analgesia in mice of different genotypes

Under conditions of the formalin test, we studied changes in the level of analgesia induced by the action of low-intensity microwaves on the antinociceptive acupuncture point (AP) E36 in mice of strains CBA/CaLac (CBA) and C57BL/6j (C57) and in albino mongrel mice. Measurements were performed under control conditions and with experimentally induced decrease in the serotonin level in the brain (by injections of DL-parachlorophenylalanine, p-CPA). In the latter cases, the duration of the pain behavioral reaction increased despite irradiation of the AP E36. In mongrel, CBA, and C57 mice, the intensity of pain manifestations was 114.4, 29.0, and 21.1% greater, respectively, than in mice of these groups with no injections of p-CPA. These facts show that the serotonergic brain system is profoundly involved in the formation of analgesia after irradiation of the AP by low-intensity microwaves, and this involvement significantly depends on the genotype of the animals. Neirofiziologiya/Neurophysiology, Vol. 38, Nos. 5/6, pp. 495–497, September–December, 2006.     

Quantitative analysis of representative proteome components and clustering of Helicobacter pylori clinical strains

BACKGROUND: Several Helicobacter pylori proteins have been reported to be associated with severe symptoms of gastric disease. However, expression levels of most of these disease-associated proteins require further evaluation in order to clarify their relationships with gastric disease patterns. Representative proteome components of 71 clinical isolates of H. pylori were analyzed quantitatively to determine whether the protein expression levels were associated with gastric diseases and to cluster clinical isolates. METHODS: After two-dimensional electrophoresis (2-DE) of H. pylori isolates, spot intensities were analyzed using pdquest 2-D Gel Analysis Software. The intensities of 10 representative protein spots, identified by peptide fingerprinting using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using quadrupole TOF MS, were subjected to the nonparametric Mann-Whitney test and hierarchical agglomerative cluster analysis. The relationship between clusters and gastric diseases was analyzed by the chi-squared test. RESULTS: Although the spot intensities of the 10 representative proteins were highly variable within each gastric disease group, the expression levels of CagA, UreB, GroEL, EF-Tu, EF-P, TagD, and FldA showed some significant differences among the gastric disease patterns. On the basis of the 10 target protein intensities, hierarchical agglomerative cluster analysis generated a dendrogram with clusters indicative of chronic gastritis/gastric cancers and gastric/duodenal ulcers. CONCLUSION: These results indicated that quantitative analysis of proteome components is a feasible method for examining disease-associated proteins and clustering clinical strains of H. pylori.     

Superoxide dismutase activity of Helicobacter pylori per se from 158 clinical isolates and the characteristics

We investigated the correlation between the SOD activity of Helicobacter pylori (H. pylori) and gastroduodenal diseases and the characteristics of strains exposed to oxidative stress. Two sequenced strains, 26695 and J99, and clinical isolates from 156 Japanese patients with gastroduodenal diseases such as gastric cancer (n= 59) and non-cancer (n= 97) were used. SOD activities of all 158 isolates were measured and were divided into three groups: high-SOD activity (>0.22, n= 2), moderate-SOD activity (0.15≦≦0.22, n= 16) and low-SOD activity (<0.15, n= 140). Expressions of H. pylori Fe-SOD were examined by western blotting with anti-H. pylori Fe-SOD antibody prepared inhouse, and the profiles of Fe-SOD activity were investigated by zymogram with activity staining in native-PAGE. The characteristics of strains from high-SOD and low-SOD groups were examined under oxidative stress by paraquat. The average of H. pylori SOD activity was significantly higher in the cancer group than in the non-cancer group (P < 0.05). However, irrespective of SOD activity level, the amount of Fe-SOD expressed was variable among individual strains. Zymogram revealed a single band in moderate-SOD and low-SOD strains, but multiple bands in high-SOD strains were observed. These bands were confirmed as H. pylori Fe-SOD. Under oxidative stress with paraquat, low-SOD strains were drastically eliminated without inducible SOD activity; however, high-SOD strains were still viable with increased SOD activity. This study is the first to exhibit the characteristics of high-SOD activity strains representing multiple bands in zymograms and the correlation between H. pylori SOD activity and gastric cancer.     

应用体内外实验筛选可降低牛乳β-乳球蛋白过敏的乳杆菌

【目的】通过体内外实验评估5种乳杆菌缓解牛乳β-乳球蛋白(BLG)过敏的作用,为今后筛选具有抗过敏活性的乳杆菌提供参考。【方法】首先体外分析5种活的/热致死的乳杆菌促进小鼠原代淋巴细胞分泌细胞因子(CK)IFN-γ和IL-4的水平,随后应用小鼠BLG过敏模型评估这5种乳杆菌抑制过敏的能力。将实验动物随机分为空白组、BLG致敏组和5种活的/热致死乳杆菌组。采用ELISA法检测各组小鼠淋巴细胞分泌Thl/Th2型CK的水平,并测定小鼠血清中总IgE和BLG特异性IgE的含量。【结果】在体外可促进淋巴细胞分泌IFN-γ、抑制IL-4,使其IFN-γ/IL-4比值(代表Thl/Th2细胞平衡)显著高于正常对照组(P<0.05)的乳杆菌,在体内实验中也能有效提高致敏小鼠淋巴细胞的IFN-γ/IL-4分泌率,并显著降低致敏小鼠血清中总IgE和BLG特异性IgE的水平(P<0.05)。相反,在体外的IFN-γ/IL-4比值较低的乳杆菌,不能缓解特异性IgE抗体介导的食物过敏反应。【结论】基于乳杆菌体外刺激小鼠原代淋巴细胞分泌Th1/Th2型CK的结果,可以预测菌株在体内具有可通过纠正Th2占优势的Th1/Th2细胞失衡,下调抗体分泌量,缓解小鼠BLG过敏症状的能力。