Density and maturation of rodlet cells in brain tissue of fathead minnows (Pimephales promelas) exposed to trematode cercariae

Evidence for the presumed linkage between the enigmatic rodlet cells of fish and exposure to helminths is anecdotal and indirect. We evaluated the proliferation and development of rodlet cells in the optic lobes of fathead minnows exposed to cercariae of Ornithodiplostomum ptychocheilus. Mean rodlet cell densities (ca. 10/mm²) in the optic lobes were similar between unexposed controls and minnows with 1- and 2-week old infections. Rodlet cell densities increased at 4 weeks p.i., reaching maxima (ca. 200/mm²) at 6 weeks p.i., followed by a decline at 9 weeks. This temporal pattern of proliferation and maturation paralleled the development of metacercariae within the optic lobes. Unencysted metacercariae develop rapidly within tissues of the optic lobes for approximately 4 weeks after penetration by cercariae, then shift to the adjacent meninges to encyst. The former stage is associated with tissue damage, the latter with massive inflammation of the meninges. Thus, peak densities and maturation of rodlet cells correspond to the period when inflammation of the meninges caused by the large metacercarial cysts is at a maximum. Our results support recent contentions that rodlet cells comprise part of the host inflammatory defence response.     

DNA ADP-Ribosylation Stalls Replication and Is Reversed by RecF-Mediated Homologous Recombination and Nucleotide Excision Repair

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The Amount of BCL6 in B Cells Shortly after Antigen Engagement Determines Their Representation in Subsequent Germinal Centers

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Cold induction of EARLI1, a putative Arabidopsis lipid transfer protein, is light and calcium dependent

As sessile organisms, plants must adapt to their environment. One approach toward understanding this adaptation is to investigate environmental regulation of gene expression. Our focus is on the environmental regulation of EARLI1, which is activated by cold and long‐day photoperiods. Cold activation of EARLI1 in short‐day photoperiods is slow, requiring several hours at 4 °C to detect an increase in mRNA abundance. EARLI1 is not efficiently cold‐activated in etiolated seedlings, suggesting that photomorphogenesis is necessary for its cold activation. Cold activation of EARLI1 is inhibited in the presence of the calcium channel blocker lanthanum chloride or the calcium chelator EGTA. Addition of the calcium ionophore Bay K8644 results in cold‐independent activation of EARLI1. These data suggest that EARLI1 is not an immediate target of the cold response, and that calcium flux affects its expression. EARLI1 is a putative secreted protein and has motifs found in lipid transfer proteins. Over‐expression of EARLI1 in transgenic plants results in reduced electrolyte leakage during freezing damage, suggesting that EARLI1 may affect membrane or cell wall stability in response to low temperature stress.     

A bacterial clone carrying sequences coding for elongation factor EF-1 alpha from Artemia

A bacterial cDNA clone was identified carrying one third of the nucleotides coding for elongation factor EF-1 alpha from the brine shrimp Artemia. The sequence of codons corresponds with the known sequence of amino acids of EF-1 alpha in the region involved.     

Preparation of chloroplast DNA from pea plastids isolated in a medium of high ionic strength

A simple, rapid, and inexpensive method for the preparation and purification of chloroplast DNA (cpDNA) from pea has been developed. The crucial step is the isolation of chloroplasts in a medium of high ionic strength (I congruent equal to 1.40 M). CpDNA from pea prepared according to this method has successfully been used for restriction enzyme mapping, Southern transfers, and cloning.     

Molecular phylogeny of Heritiera Ait on (Sterculiaceae), a tree mangrove: variations in RAPD markers and nuclear DNA content

Random amplified polymorphic DNA (RAPD) markers are used to estimate interspecific variation among mangrove and non-mangrove Heritiera fomes, H. littoralis and H. macrophylla. All the species have 2n = 38 chromosomes, with minute structural changes distinguishing the karyotype of each species. Significant variation of 4C DNA content occurs at the interspecific level. Interspecific polymorphism ranged from 14.09% between H. fomes and H. littoralis to 52.73% between H. fomes and H. macrophylla. H. macrophylla showed wide polymorphism in the RAPD marker with H. littoralis (51.23%) and H. fomes (52.73%). Two distinct RAPD products obtained from OPA-10 (1000 bp) and OPD-15 (900 bp) found characteristic molecular markers in H. macrophylla , a species from a non-mangrove habitat. H. macrophylla was more distantly related to H. fomes [genetic distance (1-F) = 0.305] than to H. littoralis [genetic distance (1-F) = 0.273]. H. littoralis was of a closer affinity to H. fomes [genetic distance (1-F) = 0.218] than to H. macrophylla.     

DNA content of spermatozoa in different genetic lines of turkeys

The variability of DNA content in turkey spermatozoa of four different lines and its correlation with body weight and sperm concentration were studied. In lines selected for lower body weight the DNA content was 2.034 and 2.036 pg per spermatozoon. In lines selected for higher body weight the DNA content was 2.267 and 2.370 pg per spermatozoon. Sperm concentration in 1 mm³ of semen, however, was higher in lines with a lower body weight (6.08–6.21 million) in comparison with lines selected for higher body weight (5.46–5.67 million). The correlations between the DNA content and sperm concentration were negative (r ranged from ?.457 to ?.860).     

Selectivity in plant food consumption in the lizard Liolaemus lutzae from southeastern Brazil

Selectivity in the consumption of plant matter from the natural habitat by the tropidurid lizard Liolaemus lutzae, endemic to the beach habitats of restingas of southeastern Brazil, and the differences in the qualitative properties of the plants consumed were studied in the Barra de MaricÝ restinga, Rio de Janeiro State. The diets of 180 lizards were analysed and the plant species present in the stomachs and their frequencies were recorded. Only four of the 19 species which occur on the beach (Phylloxerus portulacoides, Althernantera maritima, Ipomoea littoralis and I. pes-caprae) were consumed by the lizard and their frequencies in the stomachs differed from that of occurrence. Analysis of the composition of the leaves of the 13 most abundant plant species indicated that the plants consumed by the lizards had the highest contents of water, total nitrogen, total sugar and the lowest amount of gross fibres. Thus, it appears that L. lutzae is not a generalist herbivore, but feeds selectively on those plants in its environment that are most easily digested and assimilated. A seletividade no consumo de algumas entre as espécies vegetais ocorrentes no habitat de praia pelo lagarto tropidur¡deo Liolaemus lutzae e, as diferenças nas propriedades qualitativas presentes nas plantas consumidas em relação às demais plantas mais abundantes do habitat foram estudada na restinga da Barra de Maricá, Sudeste do Brasil. A dieta de 180 lagartos foi analisada tendo sido anotadas as espécies de plantas presentes no estômago e suas respectivas frequências. Apenas quatro entre as 19 espécies registradas na praia (Phylloxerus portulacoides, Althernantera maritima, Ipomoea littoralis and I. pes-caprae) foram consumidas por L. lutzae. As frequências destas na dieta do lagarto diferiram da frequência com que as plantas ocorrem no habitat. A análise da composição das folhas de 13 entre as espécies de plantas mais frequentes indicou que as plantas consumidas pelo lagarto possuem as mais elevadas proporçôes de água, nitrogênio total, açúcar total e a menor proporção de fibras. Aparentemente L. lutzae não é um herbivoro generalista mas seleciona no seu ambiente as plantas as quais são mais facilmente digeridas e assimiladas.