Oncogenes and linkage groups: Conservation during mammalian chromosome evolution

Proto-oncogenes, which represent the cellular progenitors of the transforming genes harbored by acute transforming oncogenic retroviruses, have been highly conserved during vertebrate evolution. In this report, we have assigned experimentally a subset of proto-oncogenes (SRC, ABL, FES, and FMS — all related to the SRC family) to Chinese hamster chromosomes by Southern filter hybridization analyses of DNAs isolated from both somatic cell hybrids and flow-sorted hamster chromosomes. These results demonstrate that several autosomal linkage groups containing proto-oncogenes originated prior to the radiation and speciation of mammals and have remained remarkably stable for nearly 80 million years.     

Molecular phylogeny of Plagiothecium and similar hypnalean mosses,with a revised sectional classification of Plagiothecium

We investigated the systematic relationships within the pleurocarpous moss genus Plagiothecium, based on cladistic analyses of sequence data from one nuclear (ITS) and two plastid (trnK‐psbA (matK) and rpl16 intron) DNA regions for 110 specimens of Plagiothecium and similar hypnalean mosses. Plastid and nuclear trees were mostly similar, but differed in the placement of several species of Plagiothecium, and in the relationships among other genera. The phylogenetic hypotheses based on plastid markers were well resolved; in contrast, nuclear data were insufficient to resolve some of the lowest‐level relationships within the genus. In the main Plagiothecium is natural, includes more taxa than are often recognized, and is most closely related to Isopterygiopsis and Herzogiella. Nine sections are recognized within Plagiothecium, four new: Section Pseudo‐Neckera to accommodate P. neckeroideum and its allies, Section Ortholimnobium for P. handelii and P. paleaceum, Section Struckia for P. argentatum and P. enerve, and Section Rectithecium for P. piliferum. The geographical distribution of the sections suggests that Plagiothecium originated in Asia. The derived, mainly autoicous sections Plagiothecium and Leptophyllum may have spread to the Southern Hemisphere through long distance dispersal. Three new species in section Leptophyllum (P. funale, P. pacificum and P. rhizolucidum) and two new taxa in section Pseudo‐Neckera (P. decoratum and P. neckeroideum fo. exile) are described. A limited phylogenetic hypothesis for the superficially similar hypnalean genus Taxiphyllum, which was used as outgroup, is included. A related genus (Longiella) is described, with a single species (L. plagiothecioides). The aquarium species T. barbieri is transferred to Ectropothecium.     

Zinc,cadmium, mercury and selenium in minke whales,belugas and narwhals from West Greenland

Summary Samples of muscle, liver and kidney from 24 minke whales (Balaenoptera acutorostrata), 43 belugas (Delphinapterus leucas), and 98 narwhals (Monodon monoceros) were analyzed for zinc, cadmium, mercury, and selenium. Highly significant age accumulation of mercury was found. A lower level of significance of age accumulation of cadmium in belugas and narwhals is probably due to the fact that some of the highest cadmium concentrations are in subadults and young adults. The maximum concentrations of cadmium and mercury are very high: 1.68, 73.7, and 125 g cadmium, and 9.88, 42.8, and 4.61 g mercury per g wet weight of narwhal muscle, liver and kidney, respectively. The cadmium concentrations are correlated in the three organs, as are mercury and to a lesser extent selenium concentrations. The concentrations of mercury and selenium in liver are highly correlated.     

Involvement of finger domain and kringle 2 domain of tissue-type plasminogen activator in fibrin binding and stimulation of activity by fibrin.

Human tissue-type plasminogen activator (t-PA) catalyses the conversion of inactive plasminogen into active plasmin, the main fibrinolytic enzyme. This process is confined to the fibrin surface by specific binding of t-PA to fibrin and stimulation of its activity by fibrin. Tissue-type plasminogen activator contains five domains designated finger, growth factor, kringle 1, kringle 2 and protease. The involvement of the domains in fibrin specificity was investigated with a set of variant proteins lacking one or more domains. Variant proteins were produced by expression in Chinese hamster ovary cells of plasmids containing part of the coding sequence for the activator. It was found that kringle 2 domain only is involved in stimulation of activity by fibrin. In the absence of plasminogen and at low concentration of fibrin, binding of t-PA is mainly due to the finger domain, while at high fibrin concentrations also kringle 2 is involved in fibrin binding. In the presence of plasminogen, fibrin binding of the kringle 2 region of t-PA also becomes important at low fibrin concentrations.     

Über den Feinbau der Filterkammer der Kleinzikade Euscelidius variegatus Kbm. (Jassidae)

Zusammnfssung Nach lichtmikroskopischen Studien am Darmtrakt der Kleinzikade Euscelidius variegatus wird die Filterkammer dieser Tierart elektronenmikroskopisch untersucht. Alle Epithelien der Magentasche, des Filterkammerdarmes und der in diesen Organkomplex einbezogenen Kryptonephridien besitzen den gleichen Aufbau und stellen Transport-gewebe dar. Aussagen über eine bestimmte Transportrichtung und über die Art der transportierten Stoffe können nicht gemacht werden. Der Bau der Filterepithelien wird beschrieben. Im Anschluß wird die Funktionsmöglichkeit der Filterkammer in Form einer Arbeitshypothese erörtert.

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Summary After histological investigations of the alimentary tract of the leafhopper Euscelidius variegatus the submicroscopical structure of the filter chamber is investigated electronmicroscopically. The construction of the filter epithelia is described. All epithelia in the filter chamber have the same fine structure and serve as transport tissues. A definite direction of the supposed transport of substances cannot be asserted yet. A hypothesis of the function of the filter chamber is discussed.

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Herrn Privatdozent Dr. Zebe (Physiologischer Lehrstuhl) danke ich für das Entgegenkommen, die elektronenmikroskopischen Untersuchungen in seiner Abteilung durchführen zu können, den Herren Doktoren Beinbrecht und Heumann sowie Fräulein Behrsing für technische Beratung.     

Assignment of genes encoding metallothioneins I and II to Chinese hamster chromosome 3: evidence for the role of chromosome rearrangement in gene amplification.

Cadmium resistant (Cdr) variants with coordinately amplified metallothionein I and II (MTI and MTII) genes have been derived from both Chinese hamster ovary and near-euploid Chinese hamster cell lines. Cytogenetic analyses of Cdr variants consistently revealed breakage and rearrangement involving chromosome 3p. In situ hybridization with a Chinese hamster MT-encoding cDNA probe localized amplified MT gene sequences near the translocation breakpoint involving chromosome 3p. These observations suggested that both functionally related, isometallothionein loci are linked on Chinese hamster chromosome 3. Southern blot analyses of DNAs isolated from a panel of Chinese hamster X mouse somatic cell hybrids which segregate hamster chromosomes confirmed that both MTI and MTII are located on chromosome 3. We speculate that rearrangement of chromosome 3p could be causally involved with the amplification of MT genes in Cdr hamster cell lines.     

Human DDK rescues stalled forks and counteracts checkpoint inhibition at unfired origins to complete DNA replication

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Glucose oxidase ofAspergillus niger

По методу Raper и Fennel (1953) приготовляли гетерока риотический мицелий двух различных по генотипу штаммов Aspergillus niger. Штаммы, изолированные из одного конидиофора в гетерока риотическом валике, не были однородными ни по своим морфологическим свойствам, ни способности к продукции. Повышенная продукция глюкозооксидазы была временной и в третьей генерации спор уже не наблюдалась. Причиной зтого явления было, по-видимомы, биохимическое взаимодействие между ядром и цитоплазмой двуя различных щтаммов, прекращающееся после восстановления равновесия в следущей генерасии спор.