Lamellar bodies in the epithelial bronchiolar cells in the mouse

Summary Lamellar bodies are described in the non-ciliated epithelial bronchiolar cells of the normal mouse lung. They are constituted of smooth concentric membranes, with a cytoplasmic center. They are related to mitochondria. They seem to belong to smooth endoplasmic reticulum. An origin from Golgi elements is discussed. Acknowledgment. This work was supported by Grant No 69088 of Conseil de la Recherche Médicale du Québec.     

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The levels of individual free and conjugated ecdysteroids and ecdysteroid acids, labeled from [¹⁴C]cholesterol, in five different age groups of male Manduca sexta during pupal-adult development were determined by HPLC. Eight free ecdysteroids, eight ecdysteroid phosphates, and two ecdysteroid acids were identified. Newly ecdysed pupae contained predominantly 3-epiecdysteroids in each of the free, conjugated, and acidic ecdysteroid fractions. The titer of each ecdysteroid fraction rose sharply by day 4, and this was particularly noteworthy with respect to free ecdysone and 3-epi-20-hydroxyecdysonoic acid. This stage demonstrated high degrees of ecdysone biosynthesis, oxidative catabolism, and phosphorylation. As development proceeded to day 16, total ecdysteroid titer remained constant; a decreasing free ecdysteroid titer was accompanieid by increasing titers of both conjugates and acids resulting from the metabolic processes of hydroxylation, oxidation, epimerization, and phosphorylation. The predominant metabolites throughout development were 3-epi-20-hydroxyecdysonoic acid and the phosphate conjugates of 3-epi-20-hydroxyecdysone and 3-epi-20,26-dihydroxyecdysone. The ultimate inactivation of the ecdysteroids of M. sexta during pupal-adult development is possibly mediated by two pairs of metabolically-linked processes, one leading to a 3-epiecdysteroid acid, and the other to 3-epiecdysteroid phosphates.     

Transduction of the cellular src gene and 3'' adjacent sequences in avian sarcoma virus PR2257.

When injected into chickens, a transformation-defective mutant of the Prague C strain of Rous sarcoma virus induced tumors at low incidence and after a long latency. One such tumor released a replication-defective virus designated PR2257. We molecularly cloned and sequenced the proviral DNA from quail fibroblasts transformed by PR2257. Comparison of PR2257 sequence with that of Prague C, cellular src, and 3' adjacent cellular DNA showed that the spliced version of the c-src gene and about 950 base pairs (bp) of 3'-flanking cellular DNA were transduced into PR2257. This transduction eliminated nearly all replicative genes, since the gag gene splice donor site was linked to the splice acceptor site of the src gene and, on the 3' side, recombination occurred in the end of env gene. Insertion of two extra cytosines 23 bp before and 19 bp after the c-src stop codon resulted in an extension of the coding portion up to 587 amino acids, divergence of sequences after Pro-525 and replacement of Tyr-527 by a valine residue. In addition, it appears that the 5' and 3' untranslated regions of PR2257 result from multiple recombinations between exogenous and endogenous virus genomes. Limited digestion of p66src encoded by PR2257 with Staphylococcus aureus V8 protease yielded a V2 peptide (C-terminal moiety) with an apparent molecular mass of 31 kilodaltons, consistent with the 5.7-kilodalton increase expected from the DNA sequence. The structure of PR2257 suggests that the first step in the capture of c-src gene by avian lymphomatosis viruses is the trans splicing of the viral leader mRNA to exon 1 of c-src.     

The biology of Butomus umbellatus in shallow waters with fluctuating water level

Butomus umbellatus L. is a plant species typical of littoral communities of river and stream shores. It can form continuous stands in shallow reservoirs with fluctuating water level. Their expansion is promoted by: (a) intensive vegetative reproduction of plants, (b) crowded sprouting from rhizome fragments on emerged pond bottom, (c) shallow water layer in the year following summer drainage. Expansion of B. umbellatus depends on ploidy level: two cytotypes were found in the Czech and Slovak Republics, differing in their reproductive ability. Seed production of triploids is strongly limited (they are self-incompatible within clones), while diploids can be fully fertile. Nevertheless, even in diploids, the efficiency of seed reproduction under natural conditions is low. Triploids spread by intensive vegetative reproduction, which is decisive for clonal growth of populations and their regeneration after scraping of bottom surface. During seasonal development, maximum of aboveground biomass is produced in early summer, while underground biomass increases till autumn. Growth of the plants is limited by cutting before maximum underground biomass is attained, or by duck grazing.     

Use of paired plots and multivariate analysis for the determination of goat grazing preference

Abstract. Goat grazing is examined as a possible tool for grassland management. In this paper, goat grazing preferences are described. The proportion of biomass of particular species eaten by a goat was estimated on the basis of comparison of paired quadrats. The control quadrats were clipped before grazing and their biomass was compared with the biomass in grazed quadrats. Estimates of the proportion consumed were calculated for frequent species; they were significantly different among species; the most preferred species was Polygonum bistorta, a species with broad, soft, nutritious leaves. The least grazed species were Agrostis tenuis and Galium harcynicum. Various indices of food selectivity (e.g. forage ratio, electivity index) were calculated and their behaviour was compared. Canonical Correspondence Analysis and Redundancy Analysis with appropriate covariates reflecting the block design of the experiment were used to evaluate overall changes in species composition and yielded results similar to those from the direct estimation of the proportion consumed.     

Changes in abundance of water birds species in southern Bohemia (Czech Republic) in the last 10 years

In 1981–1992, the breeding fauna of 153 fishponds was studies in three fishpond regions in south Bohemia (Czechoslovakia). On each pond, all water and wetland birds were censused by the Two-check method, which consists of adult birds counts during each breeding season (the first in the second part of May, and the second in the second part of June). We assessed the numbers of all species living in water and wetland habitats in the breeding season.The decline in abundances (expressed as number of individuals) of ducks (Anatinae), grebes (Podicipediformes), Coot (Fulica atra), Moorhen (Galinulla chloropus), Black-headed Gull (Larus ridibundus) were the most marked changes recorded. Marked increase in abundances was found in Cormorant (Phalacrocorax carbo) and Mute Swan (Cygnus olor) during the whole decade, whereas in Graylag Goose (Anser anser) the increase was restricted to the first half of the period under study. Numbers of charadriform and passeriform birds fluctuated in the dependence of water level variation.     

src-specific immunity in inbred chickens bearing v-src DNA- and RSV-induced tumors

Serological data identify a single major histocompatibility complex (MHC) class I locus in cattle. Molecular data, however, demonstrate the presence of at least two cattle MHC (BoLA) class I loci. To investigate the number of transcribed BoLA class I genes, we amplified cattle cDNA by using a single MHC class I-specific primer that hybridized to a conserved region of exon 4 and a non-specific 3 primer. Six BoLA class I cDNAs have been cloned and sequenced from a Bos taurus bull heterozygous for BoLA class I serological antigens, demonstrating the presence of a minimum of three loci. Sequence comparisons suggested that one of these cDNAs may be an unexpressed allele or the product of a nonclassical locus.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers U01186 and U01187.     

Effect of oxygen on ubiquinone-10 production by Paracoccus denitrificans

Summary Ubiquinone-10 (Q₁₀) production was measured in batch cultures of Paracoccus denitrificans grown for 8 h at increasing oxygen concentrations (0–21 % O₂ in the sparging gas). Whereas the cellular level of Q₁₀ decreased monotonically from 1.2 to 0.5 mol/g d.w., the total yield of Q₁₀ was maximal at 2.5 % O₂ and amounted to 350 nmol (0.3 mg) per L of culture.     

The effect of submergence on tuber production and dormancy in two subspecies ofBolboschoenus maritimus

Two subspecies ofBolboschoenus maritimus (L.)Palla were cultivated in submerged and non-submerged conditions. The production of tubers, the proportion of tubers remaining dormant and the time between production and reactivation were investigated. Total tuber production was found to be dependent on subspecies and may be considered a biological character of the subspecies.Bolboschoenus maritimus ssp.compactus, a subspecies of less, flooded habitats, produced more tubers with a greater capacity for growth leaving a smaller proportion of dormant tubers. Inactivity of tubers and their reactivation after one or two years were enhanced by submergence in both subspecies. The proportion of tubers that are permanently dormant as well as the dormancy of the whole plant are important features influencing the survival of populations ofB. maritimus over periods of unfavourable conditions.