Influence of temperature on the sensitivity of adrenergic β-receptors

Zusammenfassung Versuche am Ileum des Kaninchens und der Trachea des Meerschweinchens mit dem Resorcinderivat Orciprenalin⁷ bei 25 bis 42°C führten zu folgenden Ergebnissen: Temperaturerhöhung verminderte am Ileum die Affinität des Orciprenalins, an der Trachea dagegen war sie ohne Einfluss⁸.     

Effects of 2-Br-α-ergokryptine on plasma prolactin level during parturition and onset of lactation in cows

Zusammenfassung An drei Kühen wurde um den Zeitpunkt der Geburt der Effekt eines spezifischen Prolaktininhibitors (2-Br--Ergokryptin-Methan-Sulfonat=CB-154, Sandoz, Basel) auf den Plasmaprolaktinspiegel und das Einsetzen der Laktation untersucht. In allen drei Fällen konnte eine starke Hemmung der Prolaktinbasiswerte als auch eine Unterdrückung des normalerweise vor der Geburt auftretenden Prolaktingipfels erreicht werden. Ebenfalls wurde die Laktation (vergleichsweise zum Vorjahr) eindeutig gehemmt. Maximal zeigte sich die relative Unterdrückung der Milchleistung bei der Kuh, welche kurz vor und auch noch nach der Geburt mit CB-154 behandelt wurde. Prolaktin wird somit für das Rind als das massgebliche Hormon der Laktogenese — im Gegensatz zur Galaktopoese — angesehen.

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This wirk was supported by the Deutsche Forschungsgemeinschaft.     

α－球蛋白基因缺失的DNA扩增指纹图谱法分析

应用计算机辅助设计，选择α－珠蛋白基因簇中断裂好发部位或其外侧一致ＤＮＡ序列设计引物，在包含低温退火的条件下，扩增并分析α－珠蛋白基因缺失的ＤＮＡ指纹图谱，并据此对６１例α－地中海贫血病人进行了基因分型诊断．该方法稳定、可靠，可望用于临床诊断．     

A conspicuous nickel protein in microbial mats that oxidize methane anaerobically

Anaerobic oxidation of methane (AOM) in marine sediments is an important microbial process in the global carbon cycle and in control of greenhouse gas emission. The responsible organisms supposedly reverse the reactions of methanogenesis, but cultures providing biochemical proof of this have not been isolated. Here we searched for AOM-associated cell components in microbial mats from anoxic methane seeps in the Black Sea. These mats catalyse AOM rather than carry out methanogenesis. We extracted a prominent nickel compound displaying the same absorption spectrum as the nickel cofactor F430 of methyl-coenzyme M reductase, the terminal enzyme of methanogenesis; however, the nickel compound exhibited a higher molecular mass than F430. The apparent variant of F(430) was part of an abundant protein that was purified from the mat and that consists of three different subunits. Determined amino-terminal amino acid sequences matched a gene locus cloned from the mat. Sequence analyses revealed similarities to methyl-coenzyme M reductase from methanogenic archaea. The abundance of the nickel protein (7% of extracted proteins) in the mat suggests an important role in AOM.     

Alpha-helical coiled-coil structures of Trypanosoma brucei variable surface glycoproteins

We have used electron microscopy to examine purified intact variable surface glycoproteins (VSGs) from clones derived from two distinct stocks of Trypanosoma brucei. The VSG molecule from MITat 1.2 has a large elongated domain consistent with the shape of the dimeric N-terminal domain determined by X-ray analysis (see preceding paper), and a heretofore unseen short, thin fibrous tail presumed to be the C-terminal domain. Electron microscopy on DiTat 1.3, however, indicates a morphology quite distinct from that of MITat 1.2. Analysis of four VSG amino acid sequences reveals 7-fold periodicities (heptad repeats) which indicate that alpha-helical coiled-coil secondary structure elements occur in all of these VSGs, consistent with the observation of helical bundles in one VSG. These results suggest the possibility that VSG antigenic diversity may be related to a diversity in length and disposition of alpha-helical bundles and coiled-coil domains.     

Limited number of patrilines in horse domestication

Genetic studies using mitochondrial DNA (mtDNA) have identified extensive matrilinear diversity among domestic horses. Here, we show that this high degree of polymorphism is not matched by a corresponding patrilinear diversity of the male-specific Y chromosome. In fact, a screening for single-nucleotide polymorphisms (SNPs) in 14.3 kb of noncoding Y chromosome sequence among 52 male horses of 15 different breeds did not identify a single segregation site. These observations are consistent with a strong sex-bias in the domestication process, with few stallions contributing genetically to the domestic horse.     

Hox cluster disintegration with persistent anteroposterior order of expression in Oikopleura dioica

Tunicate embryos and larvae have small cell numbers and simple anatomical features in comparison with other chordates, including vertebrates. Although they branch near the base of chordate phylogenetic trees, their degree of divergence from the common chordate ancestor remains difficult to evaluate. Here we show that the tunicate Oikopleura dioica has a complement of nine Hox genes in which all central genes are lacking but a full vertebrate-like set of posterior genes is present. In contrast to all bilaterians studied so far, Hox genes are not clustered in the Oikopleura genome. Their expression occurs mostly in the tail, with some tissue preference, and a strong partition of expression domains in the nerve cord, in the notochord and in the muscle. In each tissue of the tail, the anteroposterior order of Hox gene expression evokes spatial collinearity, with several alterations. We propose a relationship between the Hox cluster breakdown, the separation of Hox expression domains, and a transition to a determinative mode of development.     

A New Variant of Penalty Method for Weak Linear Bilevel Programming Problems

We present a new variant of penalty method, which is different from the existing penalty methods, for solving the weak linear bilevel programming problems. We then transform it into a single-level optimization problem using Kuhn-Tucker optimality condition and discuss the relations between them. Finally, two examples are used to illustrate the feasibility of the proposed penalty method.     

AP－PCR在肿瘤DNA多态性研究中的应用

首次将ＡＰ－ＰＣＲ应用于ＤＮＡ多态性研究．研究ＡＰ－ＰＣＲ的反应程度，找到实现稳定扩增的适宜条件，并发现模板ＤＮＡ浓度的变化在相当范围内不会改变扩增图谱；对肿瘤、瘤周组织以及正常组织进行分析，在１１个引物中发现２个引物的扩增结果是多态的．初步结论：多态现象与癌变相关．