Autogenous growth factor production by reticuloendotheliosis virus-transformed hematopoietic cells

Reticuloendotheliosis virus strain T (REV-T)-transformed cells gave rise spontaneously to variants which secrete a factor that forms a distinct visible ring of precipitation (halo) surrounding colonies grown in soft agar. An Mr 15,000 protein was produced at higher levels by halo variants than by nonhalo-producing cells. An assay designed to detect the formation of precipitates enabled purification of an Mr 15,000 protein, p15, from serum-free medium conditioned by the growth of REV-T-transformed hematopoietic cells. Fractions enriched in p15 permitted the growth of REV-T-transformed cells under conditions where they normally failed to proliferate.     

Cell-wall lysing enzymes and products of cell-wall digestion elicit ethylene in citrus

Ethylene production was induced in Valencia oranges [ Citrus sinensis (L.) Osbcck] by injection of the fungal enzyme mixture Pectolyase ( Aspergillus japonicus ) which contains pectolytic enzymes into the peel. The mixture also stimulated production of 1-aminocyclopropane-1-carboxylic acid (ACC). Cycloheximide partially inhibited the Pectolyase-induced ethylene response. Pectin fragments, resulting from partial acid hydrolysis or Pectolyase digestion, caused an increase in ethylene production when injected into the peel of intact orange fruits. Pectic fragments produced by fungal enzymes are known to be elicitors of phytoalexins and in this study are shown to elicit ethylene in citurs.     

Sperm ultrastructure of five species of the Neotropical ant genus Pseudomyrmex (Hymenoptera: Formicidae)

The seminal vesicles of adult males of five species of Pseudomyrmex were prepared for light and transmission electron microscopy. The Pseudomyrmex spermatozoa are long and slender with similar morphology. The head region has an acrosome and a nucleus. In all the studied species, two morphologically distinct types of acrosomal vesicles were observed, a long structure, as observed in all known ants, and a pear‐shaped one, never before observed in ants. The nucleus is elongated and both condensed and loose chromatin are present. The flagellum has an axoneme, a centriolar adjunct, two mitochondrial derivatives and two accessory bodies. The centriolar, the mitochondrial derivatives and the accessory bodies are similar to observations in most ant species that have been studied. The axoneme presents an uncommon 9 + 9 + 1 microtubule arrangement and the central microtubule has 13 protofilaments. The acrosomal dimorphism and the different levels of chromatin organization are exclusive characteristics of Pseudomyrmex. Furthermore, the 9 + 9 + 1 microtubule arrangement is different from all Hymenoptera, as well as from most insects, which present a 9 + 9 + 2 arrangement. These new morphological characters that are specific to Pseudomyrmex, are valuable synapomorphies of the genus and can be used in taxonomic characterization of the Pseudomyrmecinae subfamily and in phylogenetic analyses in Formicidae family.     

Oral ontogeny of the Ayu, Plecoglossus altivelis and comparisons with the jaws of other salmoniform fishes

The Japanese Ayu, Plecoglossus altivelis Temminck & Schlegel is the sole representative of the salmoniform family Plecoglossidae. The Ayu is remarkable for its dentition which in adults comprises groups of diagonally arranged comb-like teeth in the outer tissue of the jaws. In juveniles (below 63 mm SL) the teeth are attached normally to the jaws. The transition of tooth form is correlated with a switch from zooplanktivory to algal or aufwuchs grazing. The present study follows the development of the teeth, jaws, oral cavity ethmoid and suspensorial elements in specimens ranging in size from 41–70 mm SL. The possible mode of function of the adult dentition is discussed. Comparisons are made with the jaws of other salmoniform fishes and a suite of supposed apomorphic characters are identified which are also shared with certain genera of the family Osmeridae, thus supporting the ideas of others that the Osmeridae is a paraphyletic assemblage.     

Further studies on the morphology of the Triviidae (Gastropoda: Prosobranchia) with emphasis on species from southern Africa

Aspects of the morphology of II species of Triviidae are described, including the living animal, shell, radula, mantle complex, central nervous system and reproductive system. Interspecific differences in radular morphology are important in distinguishing closely allied species. Trivia aperta, T. costata and T. verhoeft are protandric hermaphrodites while T. caluariola, T. neglccta, T. pellucidula, T. rubra, T. solandri and T. suavis are gonochoric. The elaboration of the receptaculum seminis varies between species. In T. aperta, T. calvariola, T. neglecta and T. who& the receptaculum is undivided while in T. costafa, T. pellucidula, T. solandri and T. suavis there are two or more lobes of the receptaculum.     

Gene assignment by means of somatic cell hybrids: a new method for the analysis of data

Summary A statistical approach to the interpretation of data from gene assignment with somatic cell hybrids is presented. The observed data are analysed under a variety of hypotheses. The fit to the hypotheses is compared by means of the likelihood obtained under a given hypothesis. Two of these hypotheses are related to fundamental questions: is a gene responsible for the enzyme observation and if so, is that gene located on a specific chromosome or could it change its position and be sometimes on chromosome j and, in another hybrid line, on chromosome k? The other hypotheses concern the assignment of the gene to just one of the chromosomes.To improve the traditional data analysis approach we considered additional information: the uncertainties and possible errors of laboratory methods in all our calculations and the length of the donor chromosomes in connection with one specific hypothesis.This method allows us to account for the reliability of the investigation methods and the nature of the hybrid lines involved. Data can be evaluated at different error probabilities within a realistic range in order to compare and discuss results.     

Cell kinetic studies of endothelial cells in the adenocarcinoma EO 771 and the effect of cyclophosphamide

Cell kinetic studies of endothelial cells in the adenocarcinoma EO 771 growing in C57bl/6j mice and after transplantation into Balb/c-nu/nu mice, as well as of the effect of cyclophosphamide treatment have been carried out. The³H-thymidine labelling index of endothelial cells decreases from about 8% 3–6 days after tumour inoculation to about 3% at 18 days. This decrease parallels that of the labelling index of tumour cells, i.e. there is a positive correlation between the labelling index of endothelial cells and that of tumour cells. The labelling index of endothelial cells in the tumour periphery is two to three times as high as that in the tumour centre reflecting corresponding differences in the rate of proliferation. There is no difference in the proliferation of endothelial cells whether the tumour grows in C57bl/6j or in Balb/c-nu/nu mice. After treatment with cyclophosphamide the labelling index of endothelial cells decreases within 2 days to 1–2% and remains that low despite regrowth of the tumour with increased tumour cell proliferation, indicating that tumour relapse does not depend on tumour angiogenesis.