Feinstruktur pigmentierter und unpigmentierter Photoreceptoren bei Proseriata (Plathelminthes)

The fine structure of rhabdomeric photoreceptors of Cirrifera aculeuta, Monocelis fusca and Nematoplana coelogynoporoides is described. The existence of one receptor cell and one pigmented or unpigmented mantle cell is thought to be a basic feature of the Neoophora at least. The existence of a pigment shield formed by many cells is derived, in addition to one receptor and one unpigmented mantle cell, in the eyes of Monocelis fuscu.     

Automated Sanger DNA sequencing with one label in less than four lanes on gel

Novel Sanger dideoxy sequencing with only one fluorescent dye label for the four bases of one clone and sequence determination in two lanes on polyacrylamide gel is presented, loading A greater than G in one lane and T greater than C in the other. Sequencing reactions for the two bases in each lane are carried out in one tube. At present the ratio of ddATP:ddGTP and ddTTP:ddCPT is set to 5:1 in the two tubes. Distinction between the two bases in one lane is done by comparing the different magnitudes of the peaks. This method increases the capacity since more clones may be run simultaneously on one gel, while keeping the reliability and simplicity that comes with the use of only one fluorescent dye for the four bases of one clone. At present about 200 bases are determined with the one-dye two-lane method on the EMBL's automated fluorescent DNA sequencer, using T7 DNA polymerase. The error rate in the deduced sequence is about 1%. The technique is used for the determination of overlaps in mapping projects. In principle, it is possible to determine the sequence with one dye in only one lane on the gel by choosing the proper ddNTP ratios for all four bases, carrying out reactions in one tube and applying the product in one lane, but the error rate for this one-lane method seems too high at present and further improvements in the uniformity of peaks obtainable with the T7 DNA polymerase or other enzymes are required.     

General analysis of frequency-dependent sexual selection at a multi-allelic locus

A general model is analyzed in which arbitrarily frequency-dependent selection acts on one sex of a diploid population with several alleles at one locus, as a result of viability or mating-success differences. The existence of boundary and polymorphic equilibria is examined, and conditions for local stability, internal and external, are obtained. The status of Hardy-Weinberg approximations in studying stability and approach to equilibria is also considered. The general principles are then applied to two specific models: one where genotypes fall into two phenotypic classes; and one with a hierarchy of dominance where viability and sexual selection are opposed. In the latter case it is found that, of all the equilibria present, there is one and only one which could possibly be stable: the existence of a unique globally stable equilibrium might then be inferred.     

Radical formation in the dimeric small subunit of ribonucleotide reductase requires only one tyrosine 122

The small subunit of ribonucleoside-diphosphate reductase (EC 1.17.4.1) is a homodimer. Its catalytic site contains one tyrosyl radical, which is localized to Tyr-122 in one of its polypeptide chains. The engineered Tyr-122----Phe protein was used to demonstrate that it is possible to form a correct ferric iron center in vitro in the absence of Tyr-122. Heterodimers, consisting of one Tyr-122-containing polypeptide chain and one Phe-122-containing polypeptide chain, were constructed. The heterodimer population contained one-half the amount of tyrosyl radical as compared to a homodimer with Tyr-122, i.e. every second heterodimer contains a tyrosyl radical. Thus, one Tyr-122 is sufficient for radical formation. Radical-containing heterodimers are catalytically competent.     

Comparative Analysis and Molecular Characterization of a Gene BANF1 Encoded a DNA-Binding Protein During Mitosis from the Giant Panda and Black Bear

Barrier to autointegration factor 1 (BANF1) is a DNA-binding protein found in the nucleus and cytoplasm of eukaryotic cells that functions to establish nuclear architecture during mitosis. The cDNA and the genomic sequence of BANF1 were cloned from the Giant Panda (Ailuropoda melanoleuca) and Black Bear (Ursus thibetanus mupinensis) using RT-PCR technology and Touchdown-PCR, respectively. The cDNA of the BANF1 cloned from Giant Panda and Black Bear is 297 bp in size, containing an open reading frame of 270 bp encoding 89 amino acids. The length of the genomic sequence from Giant Panda is 521 bp, from Black Bear is 536 bp, which were found both to possess 2 exons. Alignment analysis indicated that the nucleotide sequence and the deduced amino acid sequence are highly conserved to some mammalian species studied. Topology prediction showed there is one Protein kinase C phosphorylation site, one Casein kinase II phosphorylation site, one Tyrosine kinase phosphorylation site, one N-myristoylation site, and one Amidation site in the BANF1 protein of the Giant Panda, and there is one Protein kinase C phosphorylation site, one Tyrosine kinase phosphorylation site, one N-myristoylation site, and one Amidation site in the BANF1 protein of the Black Bear. The BANF1 gene can be readily expressed in E. coli. Results showed that the protein BANF1 fusion with the N-terminally His-tagged form gave rise to the accumulation of an expected 14 kD polypeptide that formed inclusion bodies. The expression products obtained could be used to purify the proteins and study their function further.     

Digital cows grazing on digital grounds

Picture a pasture open to all (...) As a rational being, each herdsman seeks to maximize his gain. Explicitly or implicitly, more or less consciously, he asks, "What is the utility to me of adding one more animal to the herd?" This utility has one negative and one positive component. 1) The positive component is a function of the increment of one animal. Since the herdsman receives all the proceeds from the sale of the additional animal, the positive utility is nearly +1. 2) The negative component is a function of the additional overgrazing created by one more animal. Since, however, the effects of overgrazing are shared by all the herdsmen, the negative utility for any particular decision-making herdsman is only a fraction of -1. Adding together the component partial utilities, the rational herdsman concludes that the only sensible course for him to pursue is to add another animal to the herd. And another; and another...     

Presence of a nucleus or nucleus-deriving factors is indispensable for the formation of the spindle, the diastema and the cleavage furrow in the blastomere of the Xenopus embryo

The present study examines the indispensability of a nucleus or nucleus-deriving factors in the induction of cleavage in Xenopus eggs by testing cleavage in Xenopus eggs fertilized with ultraviolet (UV)-damaged sperm and deprived of the female nucleus. These eggs, which contain only one UV-damaged nucleus with one set of centrioles, undergo unique cleavages. Cleavage takes place in only one of the two blastomeres formed by the immediately preceding cleavage. Histologically, only one nucleus, which does not appear to be organized into typical chromosomes, is found in one of the two blastomeres formed by the immediately preceding cleavage. The typical bipolar spindle and the diastema, or a slit of astral rays, are formed in the blastomere that contains the nucleus. By contrast, only asters lacking the spindle and the diastema are formed in the remaining blastomeres, which do not contain a nucleus. The same results are obtained in eggs that contain two UV-damaged nuclei with one set of centrioles. In these eggs, cleavage appears to occur in one or two blastomeres that contain either or both of the nuclei and one bipolar spindle. In eggs that contain one intact and one UV-damaged nuclei, cleavage takes place quite normally with each blastomere containing one nucleus or one set of chromosomes as well as one bipolar spindle. Thus, there is a very close correlation between the presence of a nucleus and the formation of the mitotic spindle, the diastema and the cleavage furrow in the blastomeres of Xenopus embryos. We conclude that the presence of a nucleus or nucleus-deriving factors is indispensable for the formation of the bipolar spindle, the diastema and the cleavage furrow in the blastomeres of the Xenopus embryos.     

A moral argument for frozen human embryo adoption

Some people (e.g., Drs. Paul and Susan Lim) and, with them, organizations (e.g., the National Embryo Donation Center) believe that, morally speaking, the death of a frozen human embryo is a very bad thing. With such people and organizations in mind, the question to be addressed here is as follows: if one believes that the death of a frozen embryo is a very bad thing, ought, morally speaking, one prevent the death of at least one frozen embryo via embryo adoption? By way of a three-premise argument, one of which is a moral principle first introduced by Peter Singer, my answer to this question is: at least some of those who believe this ought to. (Just who the “some” are is identified in the paper.) If this is correct, then, for said people, preventing the death of a frozen embryo via embryo adoption is not a morally neutral matter; it is, instead, a morally laden one. Specifically, their intentional refusal to prevent the death of a frozen embryo via embryo adoption is, at a minimum, morally criticizable and, arguably, morally forbidden. Either way, it is, to one extent or another, a moral failing.     

Cytogenetics of triplet conjugation in Tetrahymena: Origin of haploid and triploid clones

Triplet conjugation occurs frequently when three different mating types of T. thermophila are mixed under appropriate conditions. Genetic studies show that fertilization is usually tripolar, with each conjugant contributing a pronucleus to one mate and receiving a pronucleus from the other. Triplets are less common and less stable when only two mating types are mixed, and nuclear exchange is not always reciprocal. Some conjugants contribute a pronucleus but do not receive one in return. Others receive two pronuclei instead of one. Such triplets chracteristically yield one haploid, one diploid and one triploid exconjugant, all of which are able to establish vigorous clones.     

乳腺癌钼靶X线检查的漏诊及误诊分析

目的:分析乳腺癌X线检查的误诊及漏诊情况。方法:选择2013年5月至2015年5月在我院的经乳腺X线和病理检查证实的乳腺肿瘤患者135例为研究对象,比较X线检查结果与病理诊断结果的误诊率及漏诊率,并分析导致误诊及漏诊的因素。结果:135例患者中,术后病理证实为恶性肿瘤63例(46.67%),良性肿瘤72例(53.33%)。63例乳腺恶性肿瘤中,X线误诊为良性5例,误诊率为7.93%。其中1例误诊为乳腺增生,2例误诊为乳腺炎症,1例误诊为术后疤痕挛缩,1例误诊为纤维腺瘤;X线表现为肿块形态呈圆形或类圆形边缘光滑2例,肿块周围出现透亮区1例,乳腺结构扭曲1例。72例良性肿瘤中,X线误诊为恶性7例,误诊率为9.72%。其中4例为乳腺增生,2例为乳腺炎,1例为乳腺纤维瘤,1例为乳腺筋膜炎;X线表现为密度较高而边缘不清的肿块影1例,边缘似有毛刺征1例,伴有钙化、模糊无定型呈散在分布1例,部分边缘有突起或后缘凹凸不平1例,片状影2例(1例密度较高,1例密度较均匀);肿块伴乳晕增厚、乳头内陷1例。结论:乳腺X线检查的准确性受直接征象和间接征象的影响。因此,临床实践中可联合运用乳腺X线检查和乳腺超声或MRI检查,从而提高乳腺肿块诊断的准确率。     

Simplification traps

When experiments are analyzed with simple functions, one gets simple results. A trap springs when experiments show deviations from the expected simplicity. When kinetic experiments do not follow exponential curves, they simply are not of the first or pseudofirst order. They can and have to be calculated on the base of plausible reaction schemes. When dose–response curves are analyzed with logistic functions (“4-parameter fit”) and give Hill coefficients different from one, this is an experimental result stating that more than one molecule is involved in eliciting the response. If one ignores that result, one usually finds forgiving referees, but one will loose real money when one tries to develop such an unspecific compound into a drug.

Electronic supplementary material

The online version of this article (doi:10.1007/s12154-011-0069-3) contains supplementary material, which is available to authorized users.     

The preload of individual myocardial fibers

The preload of the indiviuual myocardial fibers of the left ventricle, that is, the stress exerted upon the myocardial fibers at end-diastole, is calculated by means of a set of equations. The development of the equations was based on anatomical data referring to the shape of the left ventricle and the orientation of the myocardial fibers, as well as some assumptions of minor importance. Numerical solution of the equations shows that in general, the preload increases as one advances from the apex to the equator of the left ventricle and then it decreases as one advances toward the base. The preload also changes as one advances from the epicardium to the endocardium in such a way that one can distinguish three zones: one outer, or epicardial, with low preloads, one middle with high preloads and one inner, or endocardial, with low preloads. The physiological significance of the findings as well as the validity of the assumptions on which the theory was based are discussed.     

Use of plasmid profiling as a typing method for epidemiologically related Clostridium perfringens isolates from food poisoning cases and outbreaks

Plasmid profiling was used for the characterization of Clostridium perfringens isolates involved in disease outbreaks. The usefulness of this technique was demonstrated by the retrospective examination of food and patient isolates from 10 cases and outbreaks from 1984 to 1991. The origin of three outbreaks could be clearly confirmed due to identical plasmid profiles in all isolates. In one outbreak identical plasmid patterns were found between one food and one patient isolates, while one plasmid was missing in the second patient isolate. In an additional two cases a relationship between food and patient isolates is likely, if the possibility of the loss of one plasmid in one of the isolated strains is considered. In one outbreak two faecal isolates could be related to an isolate from one of the two foods implicated as outbreak source; isolates from the other food and a third faecal sample could not be linked to any other isolate. The results from three outbreaks were largely inconclusive because plasmids were not present either in all or in some of the isolates.     

Solution structure of the CBM10 cellulose binding module from Pseudomonas xylanase A

Plant cell wall hydrolases generally have a modular structure consisting of a catalytic domain linked to one or more noncatalytic carbohydrate-binding modules (CBMs), whose common function is to attach the enzyme to the polymeric substrate. Xylanase A from Pseudomonas fluorescens subsp. cellulosa (Pf Xyn10A) consists of a family 10 catalytic domain, an N-terminal family IIa cellulose-binding module, and an internal family 10 cellulose-binding module. The structure of the 45-residue family 10 CBM has been determined in solution using NMR. It consists of two antiparallel beta-sheets, one with two strands and one with three, with a short alpha-helix across one face of the three-stranded sheet. There is a high density of aromatic residues on one side of the protein, including three aromatic residues (Tyr8, Trp22, and Trp24), which are exposed and form a flat surface on one face, in a classical polysaccharide-binding arrangement. The fold is closely similar to that of the oligonucleotide/oligosaccharide-binding (OB) fold, but appears to have arisen by convergent evolution, because there is no sequence similarity, and the presumed binding sites are on different faces.     

Theoretical development and performance evaluation for extractive fermentation using multiple extractants

Mathematical formulation was made for the performance evaluation of extractive fermentation using multiple solvents. Two types of solvent-supplying strategies were considered. One is to add multiple solvents simultaneously and the product is removed at one time. Another is to add them one by one consecutively. Computer simulation was made for batch, fed-batch, and repeated fed-batch operation of acetone-butanol fermentation to show the power of the approach. The result shows that the significant performance improvement in terms of the productivity and the product concentration is expected when two extractants such as oleyl alcohol and benzyl benzoate are used as compared with the case of using only one solvent.     

Synthesis and biological activities of 7-aza rebeccamycin analogues bearing the sugar moiety on the nitrogen of the pyridine ring

The synthesis of a new family of 7-aza-rebeccamycin analogues in which the sugar moiety is attached to the nitrogen of the pyridine ring is described. The capacity of the newly synthesized compounds to bind to DNA and to inhibit topoisomerase I has been evaluated. Their cytotoxicities toward four tumor cell lines, one murine leukemia L1210 and three human tumor cell lines, one prostate carcinoma DU145, one colon carcinoma HT29, and one non-small cell lung carcinoma A549, have been determined. Their abilities to inhibit the checkpoint kinase Chk1 have been evaluated.     

甲基营养菌的研究进展

甲基营养菌是一类能够利用一碳化合物作为唯一碳源和能源的微生物,它们在自然界分布广泛.研究表明,甲基营养菌能够直接利用一碳化合物,将其转化成自身代谢的一碳单位,并为生物体提供能源和碳骨架,这组成了一碳代谢的主要部分,它是一种新的代谢体系,可以作为一种新的代谢模式来研究生物代谢和生物进化.本文结合本实验室Methylobacterium sp.MB200的研究情况,主要从分类学、代谢途径、基因组学和应用等方面,论述了甲基营养菌的研究进展.     

Swelling of biocolloids

Summary Agar of equal concentration swells differently according to whether the gel is a freshly prepared one, a wilted (partially dehydrated) one, or a dried and then partially swollen one.     

中国毛茛科植物小志(十七)

在本文中描述了乌头属和翠雀属各一新种和一新亚种,唐松草属一新种,侧金盏花属一新亚种,以及毛茛属五新种,首次报道了圆叶唐松草在中国西藏南部的分布,在对叶、雄蕊和心皮的形态特征进行了分析之后认为,这种植物与特产云南的糙叶唐松草有一定亲缘关系。