Location of ribosome-binding sites in the nin5 region of bacteriophage lambda

Seven ribosome-binding sites on DNA have been located within the region defined by the nin5 deletion as well as several ribosome-binding sites on each side of the nin5 region. These were mapped by electron microscopy relative to the end points of the nin5 deletion and two Tn903 transposons, one inserted into gene Rz and another inserted near gene Q. These ribosomes binding sites within the nin5 region may correspond to polypeptide initiation sites for up to seven new dispensible lambda genes.     

Human liver aldehyde dehydrogenase in Chinese and Asiatic Indians: Gene deletion and its possible implications in alcohol metabolism

Two separate human liver aldehyde dehydrogenases exist which show differences in substrate specificity, cation inhibition or activation, and molecular weight. In this paper we report a common absence of enzyme 2 in Chinese which may be taken to indicate a gene deletion coding for this enzyme. The possible implication of this gene deletion among Chinese is discussed.     

The N protein of bacteriophage lambda, defined by its DNA sequence, is highly basic.

Nucleotide sequence has been determined for the restriction fragments and cloned DNA from the pL-N-tL1 region of bacteriophage lambda. A unique reading frame for the N gene is defined by the absence of natural nonsense codons and by the presence of seven nonsense codons generated by mutations in N. This reading frame is initiated at two alternative ATG codons, the second of which is probably the in vivo translation start. Reading is stopped at a single TAG codon. The protein coded is therefore 133 or, more probably, 107 amino acids long, rich in lysine, arginine and proline.     

Non-random intrachromosomal distribution of chromatid aberrations induced by X-rays,alkylating agents and ethanol in Vicia faba

A reconstructed karyotype of Vicia faba with all chromosomes individually distinguishable was treated with triethylene melamine (TEM), cytostasan (CYT) (a new benzimidazol nitrogen mustard), mitomycin C (MI), ethanol (EA) and X-rays. The distribution within chromosomes of induced chromatid abberations was non-random for all agents. The number of segments involved in aberration clustering corresponded to the number of sites representing constitutive heterochromatin, or the regions immediately adjacent to these, as evidenced by the position of Giemsa marker bands. Which of these potential regions of aberration clustering reacted with preferential involvement in aberrations was, in part at least, dependent upon the inducing agent used. It is argued that this may be due to differences in the base composition and/or molecular conformation of heterochromatic regions. Unexpectedly, the distribution pattern of chromatid aberrations induced by mitomycin C was found to be different from those after treatment with the alkylating agents TEM and cytostasan although mitomycin C is assumed to induce aberrations via alkylation. If mitomycin C-induced aberrations are indeed due to alkylation, this indicates that different alkylating agents do not necessarily result in identical patterns of abberation clustering. The other two alkylating agents and ethanol resulted in similar patterns of preferential distribution of abberations. X-Ray induced chromatid aberrations also showed a non-random intrachromosomal distribution, but the clustering was less pronounced than after treatment with the chemical agents.     

Male‐specific alterations in structure of isolation call sequences of mouse pups with 16p11.2 deletion

16p11.2 deletion is one of the most common gene copy variations that increases the susceptibility to autism and other neurodevelopmental disorders. This syndrome leads to developmental delays, including speech impairment and delays in expressive language and communication skills. To study developmental impairment of vocal communication associated with 16p11.2 deletion syndrome, we used the 16p11.2del mouse model and performed an analysis of pup isolation calls (PICs). The earliest PICs at postnatal day 5 from 16p11.2del pups were found altered in a male‐specific fashion relative to wild‐type (WT) pups. Analysis of sequences of ultrasonic vocalizations (USVs) emitted by pups using mutual information between syllables at different positions in the USV spectrograms showed that dependencies exist between syllables in WT mice of both sexes. The order of syllables was not random; syllables were emitted in an ordered fashion. The structure observed in the WT pups was identified and the pattern of syllable sequences was considered typical for the mouse line. However, typical patterns were totally absent in the 16p11.2del male pups, showing on average random syllable sequences, while the 16p11.2del female pups had dependencies similar to the WT pups. Thus, we found that PICs were reduced in number in male 16p11.2 pups and their vocalizations lack the syllable sequence order emitted by WT males and females and 16p11.2 females. Therefore, our study is the first to reveal sex‐specific perinatal communication impairment in a mouse model of 16p11.2 deletion and applies a novel, more granular method of analysing the structure of USVs.     

线粒体DNA4977bp大片缺失突变与喉癌的相关性研究

目的:探讨线粒体DNA4977bp大片缺失突变与喉癌的相关性。方法:选择2016年1月～2017年6月我院收治的喉乳头状瘤、喉癌患者,分别纳入良性肿瘤组、恶性肿瘤组,每组各150例。取两组患者的病变组织标本,分离癌及癌旁组织,提取总DNA,采用PCR扩增测序技术检测两组标本中线粒体DNA4977bp大片缺失突变情况。结果:基因测序结果显示恶性肿瘤组患者的线粒体DNA4977bp缺失突变率为39.33%,高于良性肿瘤组患者的1.33%,差异具有统计学意义(P0.05)。不同肿瘤分期患者的线粒体DNA4977bp缺失突变率比较,差异具有统计学意义(P0.05),且III期患者的突变率II期 I期 IV期;淋巴结转移患者的线粒体DNA4977bp缺失突变率高于淋巴结未转移患者差异具有统计学意义(P0.05)。结论:线粒体DNA4977bp大片缺失突变与喉癌的发生有关,可能促进的发生和进展。     

ADAMTSL6β promotes fibrillin‐1 microfibril assembly,which is possibly mediated via binding through the third thrombospondin type I domain to fibrillin‐1

Fibrillin‐1 is the major component of extracellular matrix microfibrils. Microfibrils dysfunction is responsible for the onset of various connective tissue diseases, including Marfan syndrome. Although ADAMTSL (a disintegrin and metalloproteinase with thrombospondin motifs‐like) 6β is one of the fibrillin‐1 binding proteins, the detailed mechanism underlying the involvement of ADAMTSL6β in microfibril formation remains unclear. In this study, we created deletion mutants of ADAMTSL6β and examined their interactions with fibrillin‐1 assembly. Pull‐down assay of the ADAMTSL6β deletion mutants and fibrillin‐1 protein revealed that ADAMTSL6β binds to fibrillin‐1 through the third thrombospondin type I domain. Furthermore, we observed that formation of fibrillin‐1 matrix assembly was enhanced in MG63 cells, expressing full‐length ADAMTSL6β, when compared with that of wild type MG63 cells. While MG63 cells expressing Δ TSP3‐ADAMTSL6β form showed enhanced assembly formation, Δ TSP2‐ADAMTSL6β form did not enhance that, indicating the difference between Δ TSP2‐Δ TSP3 has a critical role for fibrillin‐1 assembly. As the difference of Δ TSP2‐Δ TSP3 is the third thrombospondin type I domain, we concluded that the third thrombospondin type I domain of ADAMTSL6β influence the microfibril formation. Our data are the functional presentation of the biological role of ADAMTSL6β in the process of microfibril formation.     

Komagataeibacter rhaeticus 3-15全基因组及葡萄糖脱氢酶基因缺失体的构建

细菌纤维素(BC)是一种新型的可再生、可降解的生物高分子材料。为了最大程度的发挥BC生产菌株K.rhaeticus 315的生产能力,本文首先对K.rhaeticus 315进行全基因组测序,通过功能基因的注释、分析碳源代谢流向。结果显示,该菌株碳代谢特征之一是缺乏磷酸果糖激酶的编码基因,不能通过EMP途径代谢糖类碳源,而是主要通过PPP途径和TCA途径代谢碳源,维持菌体生长和BC合成。由于葡萄糖脱氢酶的存在,该菌株在合成BC的同时生成大量副产物—葡萄糖酸。为此,本文通过敲除葡萄糖酸合成酶相关基因,即葡萄糖脱氢酶基因gcd,构建葡萄糖脱氢酶基因缺失重组株(gcd^-),将葡萄糖酸的生成量降低了77%。     

Removal of a C-terminal serine residue proximal to the inter-chain disulfide bond of a human IgG1 lambda light chain mediates enhanced antibody stability and antibody dependent cell-mediated cytotoxicity

Optimization of biophysical properties is a critical success factor for the developability of monoclonal antibodies with potential therapeutic applications. The inter-domain disulfide bond between light chain (Lc) and heavy chain (Hc) in human IgG1 lends structural support for antibody scaffold stability, optimal antigen binding, and normal Fc function. Recently, human IgG1λ has been suggested to exhibit significantly greater susceptibility to reduction of the inter Lc-Hc disulfide bond relative to the same disulfide bond in human IgG1κ. To understand the molecular basis for this observed difference in stability, the sequence and structure of human IgG1λ and human IgG1κ were compared. Based on this Lc comparison, three single mutations were made in the λ Lc proximal to the cysteine residue, which forms a disulfide bond with the Hc. We determined that deletion of S214 (dS) improved resistance of the association between Lc and Hc to thermal stress. In addition, deletion of this terminal serine from the Lc of IgG1λ provided further benefit, including an increase in stability at elevated pH, increased yield from transient transfection, and improved in vitro antibody dependent cell-mediated cytotoxicity (ADCC). These observations support the conclusion that the presence of the terminal serine of the λ Lc creates a weaker inter-chain disulfide bond between the Lc and Hc, leading to slightly reduced stability and a potential compromise in IgG1λ function. Our data from a human IgG1λ provide a basis for further investigation of the effects of deleting terminal serine from λLc on the stability and function of other human IgG1λ antibodies.     

Polymerase γ efficiently replicates through many natural template barriers but stalls at the HSP1 quadruplex

Faithful replication of the mitochondrial genome is carried out by a set of key nuclear-encoded proteins. DNA polymerase γ is a core component of the mtDNA replisome and the only replicative DNA polymerase localized to mitochondria. The asynchronous mechanism of mtDNA replication predicts that the replication machinery encounters dsDNA and unique physical barriers such as structured genes, G-quadruplexes, and other obstacles. In vitro experiments here provide evidence that the polymerase γ heterotrimer is well-adapted to efficiently synthesize DNA, despite the presence of many naturally occurring roadblocks. However, we identified a specific G-quadruplex–forming sequence at the heavy-strand promoter (HSP1) that has the potential to cause significant stalling of mtDNA replication. Furthermore, this structured region of DNA corresponds to the break site for a large (3,895 bp) deletion observed in mitochondrial disease patients. The presence of this deletion in humans correlates with UV exposure, and we have found that efficiency of polymerase γ DNA synthesis is reduced after this quadruplex is exposed to UV in vitro.