Fanconi anemia: evidence for linkage heterogeneity on chromosome 20q

Fanconi anemia is a rare autosomal recessive disorder in which affected individuals are predisposed to acute myelogenous leukemia and other malignancies. We report the results of a genetic linkage study involving 34 families enrolled in the International Fanconi Anemia Registry. A significant lod score was obtained between D20S20, an anonymous DNA segment from chromosome 20q, and Fanconi anemia (Zmax 3.04, theta max = 0.12). However, six other anonymous DNA segments from chromosome 20q, including D20S19, which is highly polymorphic and tightly linked to D20S20, showed no or only weak evidence for linkage to Fanconi anemia. An admixture test revealed significant evidence for linkage heterogeneity (chi 2 = 6.10, P = 0.01) at the D20S19 locus. Lod scores suggestive of linkage between Fanconi anemia and this locus were obtained with two of the largest kindreds studied (lods = 2.6 and 2.1, at theta = 0.001). Thus, our data support the provisional assignment of a Fanconi anemia gene to chromosome 20q.     

High production of alkaline protease byBacillus licheniformis in a fed-batch fermentation using a synthetic medium

Summary High production (9016 U/ml) of alkaline protease byBacillus licheniformis has been achieved. A 49% increase in production was achieved by the method used as compared with a batch process. By using a synthetic medium and a fed-batch operation controlled by the Advanced Fermentation Software (AFS) package, it was found that the keys to high production of protease are: (i) to maintain a low concentration of glucose (<0.43 g/l) in the medium; (ii) to control pH at a certain level (pH 6.50) in the culture; and (iii) to use rough type colonies as the starting culture. Our fed-batch fermentation process successfully simulates and surpasses ordinary batch fermentation processes. By using ammonium sulfate instead of soy bean flour as the only nitrogen source, an expected benefit was the elimination of unpleasant odors caused by natural organic nitrogenous components in the media. This would improve the industrial production environment.     

The 5S RNA genes of Schizosaccharomyces pombe.

The genomic arrangement and sequences of S. pombe 5S RNA genes are reported here. The 5S gene sequences appear to be dispersed within the genome, and are found independently of other rRNA genes. The sequences of two 5S genes examined show identical coding regions of 119 base pairs but have widely varying flanking sequences. A tRNAAsp gene is found in the 3' flanking region of one of the 5S genes. The tRNAAsp gene is faithfully transcribed in an X. laevis in vitro system, while the 5S genes are not transcribed in this system. The phylogenetic position of S. pombe is examined through comparison of 5S RNA sequences.     

Molecular cloning and characterization of double-stranded cDNA coding for bovine chymosin

A full-length cDNA copy of the mRNA encoding calf chymosin (also known as rennin), a proteolytic enzyme with commercial importance in the manufacture of cheese, has been cloned in an f1 bacteriophage vector. The nucleotide sequence of the cDNA was determined, and translation of that sequence into amino acids predicts that the zymogen prochymosin is actually synthesized in vivo as preprochymosin with a 16 amino acid signal peptide. In vitro translation of total poly(A)-enriched RNA from the calf fourth stomach (abomasum) and immunoprecipitation with antichymosin antiserum revealed that a form of chymosin (probably preprochymosin judging from the M_r-value) is the major in vitro translation product of RNA from that tissue. Gel-transfer hybridization of restriction endonuclease-cleaved bovine chromosomal DNA with labeled cDNA probes indicated that the two known forms of chymosin, A and B, must be products of two different alleles of a single chymosin gene.     

Participation of lipopolysaccharide in hyperplasic adipose expansion: Involvement of NADPH oxidase/ROS/p42/p44 MAPK‐dependent Cyclooxygenase‐2

Obesity is a world‐wide problem, especially the child obesity, with the complication of various metabolic diseases. Child obesity can be developed as early as the age between 2 and 6. The expansion of fat mass in child age includes both hyperplasia and hypertrophy of adipose tissue, suggesting the importance of proliferation and adipogenesis of preadipocytes. The changed composition of gut microbiota is associated with obesity, revealing the roles of lipopolysaccharide (LPS) on manipulating adipose tissue development. Studies suggest that LPS enters the circulation and acts as a pro‐inflammatory regulator to facilitate pathologies. Nevertheless, the underlying mechanisms behind LPS‐modulated obesity are yet clearly elucidated. This study showed that LPS enhanced the expression of cyclooxygenase‐2 (COX‐2), an inflammatory regulator of obesity, in preadipocytes. Pretreating preadipocytes with the scavenger of reactive oxygen species (ROS) or the inhibitors of NADPH oxidase or p42/p44 MAPK markedly decreased LPS‐stimulated gene expression of COX‐2 together with the phosphorylation of p47^phox and p42/p44 MAPK, separately. LPS activated p42/p44 MAPK via NADPH oxidase‐dependent ROS accumulation in preadipocytes. Reduction of intracellular ROS or attenuation of p42/p44 MAPK activation both reduced LPS‐mediated COX‐2 expression and preadipocyte proliferation. Moreover, LPS‐induced preadipocyte proliferation and adipogenesis were abolished by the inhibition of COX‐2 or PEG₂ receptors. Taken together, our results suggested that LPS enhanced the proliferation and adipogenesis of preadipocytes via NADPH oxidase/ROS/p42/p44 MAPK‐dependent COX‐2 expression.     

黄土丘陵区退耕地土壤可溶性氮组分季节变化与水热关系

为探究黄土丘陵区退耕地植被恢复土壤有效氮素养分累积的季节动态变化特征及水热驱动效应,以邻近坡耕地为对照,分析了植被恢复15 a的刺槐、柠条、荒草地土壤可溶性氮组分密度、分布比例在4—10月份内的动态变化状况及其与土壤温度和含水量间的关系。结果表明,整个采样期间,0—30 cm土层土壤硝态氮、可溶性有机氮和可溶性全氮动态变化显著,且各可溶性氮组分中仅硝态氮随土层变化差异显著。其中土壤硝态氮变化幅度整体为0.13—1.71 g/m~2,占可溶性全氮的5.1%—52.1%,其最大值出现在4月份,最小值出现在10月份;可溶性有机氮整体变化幅度为0.29—2.92 g/m~2,占可溶性全氮的30.9%—85.3%,在4月份和8月份分别达最小值和最大值;铵态氮动态变化不显著,4—10月份整体变化幅度为0.17—0.74 g/m~2,占6.4%—21.4%,其最小值出现在10月份,最大值出现在4月份;可溶性全氮整体变化幅度为1.25—3.52 g/m~2。可溶性氮组分中,各组分所占比例为可溶性有机氮硝态氮铵态氮,并且可溶性有机氮与硝态氮所占比例动态变化趋势相反。刺槐、柠条林和荒草地0—30 cm土壤硝态氮平均约为耕地的3.42倍、2.54倍和1.26倍,铵态氮平均为耕地的1.71倍、1.37倍和1.30倍,可溶性有机氮约为1.64倍、1.31倍和1.23倍。可溶性氮组分受土壤含水量的影响大于土壤温度,硝态氮对土壤含水量的变化最为敏感,而可溶性全氮则对土壤温度变化最为敏感。综上所述,人工林植被恢复有利于提高土壤可溶性氮组分,增加氮的有效性,同时除铵态氮外,土壤可溶性氮组分随季节变化显著。     

祁连山北坡退化林地植被群落的自然恢复过程及土壤特征变化

采用长期定位观测的方法,研究了祁连山北坡退化林地人工抚育下2001-2008年间植被群落的自然恢复过程和土壤特征变化。结果表明:人为干扰消除后,退化林地群落环境逐渐优化,群落的科、属、种均明显增加,物种成员更替频繁;灌木和乔木物种出现后,群落垂直高度增大,群落结构出现成层现象;群落总体多样性指数呈不断增大的趋势,在空间结构上,Patrick丰富度指数、Shannon-Wiener多样性指数和Simpson优势度指数表现出:草本层>灌木层>乔木层的规律,而Pielou均匀度指数变化相反;土壤含水量、土壤有机碳和全氮含量随植被恢复均不断增加。在实施封育禁牧措施后,退化林地实现了由草本群落-灌木群落-乔木群落方向的快速演替,当恢复到早期的先锋乔灌混交阶段时,群落的物种组成、结构和多样性趋于复杂化,土壤性状也得到一定改善,显示出相对较好的适应性和恢复效果。