尖孢镰孢一新硝酸盐营养突变类型与营养体亲和性

从73个尖孢镰孢(Fusarium oxysporum)不同专化型菌株上获得684个硝酸盐营养突变株(nit mutant)。作相关氮源利用试验及亚硝酸反应后,鉴定出一新硝酸盐营养突变类型:亚硝酸盐还原酶结构基因类型,命名为nit8,占总突变株的6.7%。同时被鉴别的还有nit1、nit3和Nit M三种突变类型,它们分别占突变株总数的81.0%,3.8%和8.5%。此外,首次引入一种亚硝酸反应在这类研究中的应用,还提出了互补指数概念与公式来表示nit突变株营养体之间亲和的能力。     

The α2(XI) collagen gene lies within 8 kb of Pb in the proximal portion of the murine major histocompatibility complex

A number of serious hereditary disorders are now known to be associated with defective expression of collagen genes, and these findings have underscored the important and varied roles that the collagen family of genes must play during normal mammalian development. Although the activities of genes encoding the quantitatively major types of collagen are fairly well characterized, functions of the many minor types of collagen remain a matter of speculation. As a first step toward a functional analysis of type XI collagen, a member of this class of poorly understand minor collagen proteins which is expressed primarily in hyaline cartilage, we have used human probes for the gene encoding the protein's 2-subunit (COL11A2) to isolate and map homologous murine DNA sequences. Our results demonstrate that Col11a-2 is embedded within the major histocompatibility complex (MHC), within 8.4 kb of the class II pseudogene locus, Pb, and confirm that human and murine 2(XI) collagen genes are located in very similar genomic environments. The conserved location of these genes raises the possibility that type XI collagen genes may contribute to one or more of the diverse hereditary disorders known to be linked to the MHC in mouse and human.     

两种培养液对人外周血单个核细胞活力影响的比较观察

本文比较了自制细胞培养基和日本1640产细胞培养基对人外周血单个核细胞活力的影响,结果表明两种细胞培养基用于PBMC培养24h、48h、72h后、自制细胞培养基培养的细胞存活率均明显高于日本产1640培养基(P<0.01).说明自制细胞培养基可取代日本产1640培养基而用于人PBMC的实验培养.     

Structures of paralytic acylpolyamines from the spider Agelenopsis aperta

The structures are given for five paralytic acylpolyamines from the venom of the funnel web spider, Agelenopsis aperta. The acyl moieties are derived from (3-indolyl)acetic acid, (4-hydroxy-3-indolyl)acetic acid, and 4-hydroxybenzoic acid. The polyamine portions of the toxins are novel. Three toxins (AG489, AG505, and AG452) contain 1, 5, 9, 13, 18, 22-hexaazadocosane which is unique as a natural polyamine because of its length and hydroxylation at the 5-aza position. The polyamine portions of two other alpha-agatoxins (AG488 and AG504) are unusual also, containing guanidinooxy moieties.     

Binding of epithelial cells to lectin-coated surfaces

Summary Epithelial cells may relate to their basement membrane substrates via lectin-like interactions. In a model system for study of this type of interaction, lectin-coated bacteriological plastic petri dishes were presented as substrates for epithelial cell adhesion. Of 21 lectins tested by mixed agglutination against two epithelial cell types, Madin-Darby canine kidney (MDCK), and human embryonic kidney cells (HEK), nine gave less than 5% rosettes and 12 gave 5 to 50% rosettes. Wheat germ agglutinin (WGA) andGeodia cydonium lectin gave the highest percentage of rosettes. Wheat germ agglutinin was readily adsorbed to plastic surfaces and maintained specificity in binding interactions. Both MDCK and HEK cells attached as well to WGA coated petri dishes as to conventional tissue culture dishes. Furthermore, both spread over the lectin-coated surfaces. The MDCK cells grew to confluence and could be subcultured and maintained indefinitely on such surfaces, although WGA in solution was toxic to the cells in concentrations as low as 0.1 to 1.0 μg/ml. Cell attachment to WGA coated dishes was blocked by cycloheximide only if the cells had been preincubated with the inhibitor for several hours. Cell attachment was not inhibited by pretreatment of cells with neuraminidase. Precoating cells with WGA blocked binding to both WGA-coated surfaces and untreated tissue culture dishes. Cells attached to WGA-coated dishes could not be readily dislodged by trypsin-EDTA for the first 2 h after subculture. By 4 h, attachment was again trypsin sensitive, suggesting that the cells synthesized a trypsin-sensitive material that was laid down between the cell surface and the WGA-coated dish. Regeneration of trypsin sensitivity was not blocked by cycloheximide. This work was supported by Research Grant AG01986 from the National Institutes of Health, Bethesda, Maryland.     

Evidence for the role of a trypsin-like enzyme in the hamster sperm acrosome reaction.

Acrosome reactions occurring in vitro in hamster sperm capacitated by bovine follicular fluid were severly inhibited by four synthetic trypsin inhibitors and by Zn2+. Three polypeptide trypsin inhibitors and a synthetic chymotrypsin inhibitor did not inhibit the acrosome reaction, and Ca2+ overcame the inhibition by Zn2+. These results suggest that a trypsin-like enzyme (possibly acrosin) plays a role in the acrosome reaction.     

黄芩的花粉母细胞减数分裂及核型分析

采用压片法,对黄芩花粉母细胞减数分裂及核型进行了研究。结果表明:黄芩的大多数花粉母细胞减数分裂中染色体的行为正常,在终变期同源染色体配对后可形成9个二价体,后期Ⅰ染色体以9∶9的方式向细胞两极分离,其减数分裂为同时型;在少数花粉母细胞减数分裂中观察到落后染色体、染色体桥等异常行为;其花粉粒育性为76.49%。黄芩的染色体数目为2n=2X=18,核型公式为K(2n)=2X=18=16m+2 sm,染色体相对长度组成为2n=1 s+4M1+3M2+1L,其核型为"1A"型。     

常用食品防腐剂抗菌作用的研究

采用杯碟法和琼脂平板点种法分别测定２０种常用食品防腐剂对３０株菌的抑菌圈直径和最低抑菌浓度,借此判断药剂抗菌力的大小。实验结果表明,在所测２０种防腐剂中,对细菌抑制力最强者是乙酸,对霉菌和酵母菌抑制力最强者是富马酸二甲酯。     

Engineered Pentafunctional Minicellulosome for Simultaneous Saccharification and Ethanol Fermentation in Saccharomyces cerevisiae

Several yeast strains have been engineered to express different cellulases to achieve simultaneous saccharification and fermentation of lignocellulosic materials. However, successes in these endeavors were modest, as demonstrated by the relatively low ethanol titers and the limited ability of the engineered yeast strains to grow using cellulosic materials as the sole carbon source. Recently, substantial enhancements to the breakdown of cellulosic substrates have been observed when lytic polysaccharide monooxygenases (LPMOs) were added to traditional cellulase cocktails. LPMOs are reported to cleave cellulose oxidatively in the presence of enzymatic electron donors such as cellobiose dehydrogenases. In this study, we coexpressed LPMOs and cellobiose dehydrogenases with cellobiohydrolases, endoglucanases, and β-glucosidases in Saccharomyces cerevisiae. These enzymes were secreted and docked onto surface-displayed miniscaffoldins through cohesin-dockerin interaction to generate pentafunctional minicellulosomes. The enzymes on the miniscaffoldins acted synergistically to boost the degradation of phosphoric acid swollen cellulose and increased the ethanol titers from our previously achieved levels of 1.8 to 2.7 g/liter. In addition, the newly developed recombinant yeast strain was also able to grow using phosphoric acid swollen cellulose as the sole carbon source. The results demonstrate the promise of the pentafunctional minicellulosomes for consolidated bioprocessing by yeast.     

Perfectly registered multiphoton and reflectance confocal video rate imaging of in vivo human skin

We present a multimodal in vivo skin imaging instrument that is capable of simultaneously acquiring multiphoton and reflectance confocal images at up to 27 frames per second with 256 × 256 pixel resolution without the use of exogenous contrast agents. A single femtosecond laser excitation source is used for all channels ensuring perfect image registration between the two‐photon fluorescence (TPF), second harmonic generation (SHG), and reflectance confocal microscopy (RCM) images. Images and videos acquired with the system show that the three imaging channels provide complementary information in in vivo human skin measurements. In the epidermis, cell boundaries are clearly seen in the RCM channel, while cytoplasm is better seen in the TPF imaging channel, whereas in the dermis, SHG and TPF channels show collagen bundles and elastin fibers, respectively. The demonstrated fast imaging speed and multimodal imaging capabilities of this MPM/RCM instrument are essential features for future clinical application of this technique. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)