Midsummer heat wave effects on lacustrine plankton: Variation of assemblage structure and fatty acid composition

The effects of the 2003 European heat wave on a freshwater plankton assemblage and its fatty acid (FA) composition were investigated. Composition and FA profiles of four size categories of planktonic organisms collected in 2003 were compared to those of the colder year 2002.     

Evaluation of chemotherapy in experimental toxocarosis by determination of specific immune complexes

Parasitism by the larval phase of Toxocara canis is a chronic process in which the larvae survive in the tissues, resulting in the constant stimulation of the immune system. As a result, the detection of specific antibodies may not reflect the active state of the parasite. We have studied the dynamics of the production of specific immune complexes by ELISA with the monoclonal antibody TC-1 in rabbits inoculated with single and multiple doses of T. canis eggs. We also compared this with the production of specific antibodies and their possible modification after treatment with mebendazole. The specific antibodies against excretory-secretory antigen were detected with peaks at 10 and 12 weeks depending on the dose and remained positive during the entire experiment (62 weeks). Treatment caused an increase in the level of detectable antibodies dropping to similar levels to the controls. Specific immune complexes were detected only in multiple doses, and were then positive during the entire experiment. From the beginning of treatment the values of immune complexes fell quickly, remaining at undetectable levels during the rest of the experiment. For this reason the detection of specific immune complexes is a valid technique for monitoring the efficiency of treatment.     

Effect of converting enzyme inhibition with captopril on baroreflex sensitivity

Clinical and experimental data suggest that both Captopril and angiotensin II (AII) reduce baroreflex responsiveness, and the main action of this converting enzyme inhibitor (CEI) seems clear to suppress AII synthesis. The aim of this work is to investigate this striking similarity of effects. We have verified that CEI (4 mg/kg) originates tachycardia significantly lower (P less than 0.001) than that produced in response to a similar hypotension elicited by an unspecific vasodilator: sodium nitroprusside (10-45 micrograms/kg min). CEI SQ 20881 has been reported to increase plasma vasopressin concentrations (AVP); this peptide is also known to modify baroreflex responses and has a small direct negative chronotropic effect. However, our determinations of AVP do not show any difference between the control group and the group treated with Captopril (4.78 +/- 0.87 and 5.26 +/- 0.19 pg/ml respectively). On the other hand, although CEI did not modify the rapid responses of heart rate (HR) to changes of mean arterial pressure (MAP), the decrease of MAP induced by nitroprusside was higher in the group treated with Captopril than in control group; it could mean a baroreflex ability decrease to buffer the hypotension. However, AII elicited a strong impairment of both rapid responses of HR and the buffering of hypotension produced by NP, these actions being suggested as centrally mediated. These results could indicate that the suppression of peripheral AII synthesis and therefore, the lack of pre- and postjunctional sympathetic potentiation owing to this hormone, is responsible for the absence of tachycardia under Captopril treatment.     

Centrifugation of 2-cell mouse ova: cytoplasm stratification and recovery

Summary Two-cell mouse ova, which were centrifuged for l h at 70 000–90 000xg, showed a precise stratification of the cytoplasm and an elongation of the nucleus. The ova were fixed at different times and observed by light and electron microscopy using cytochemical methods and detergent extractions. Within 40 min after centrifugation the normal-looking morphology was recovered except for the persisting lipid caps at the centripetal poles of the blastomeres. Cleavage, compaction and blastulation were not prevented by centrifugation. Treatments with colcemid or cytochalasin D delayed but did not impair recovery. These results suggest that a resilient cytoskeletal structure may be involved in this kind of embryonic regulation.     

Ecophysiology and distribution of the endemic leafless spurgeEuphorbia aphylla and the introducedE. tirucalli (Euphorbiaceae,Euphorbia sect.Tirucalli) in the Canary Islands

The leafless spurgeEuphorbia aphylla (Euphorbiaceae), an endemic species restricted to several of the Canary Islands where it inhabits coastal and arid localities, expresses Crassulacean Acid Metabolism (CAM) when it is subjected to summer drought. A flexible CAM is consistent with the general ecology of the species. It is the only member of sect.Tirucalli native to the Canary Islands and is at the north-western edge of the section's biogeographical range. The other members of the section have a paleotropic distribution and are found throughout Africa. Many of them are regarded as obligate CAM plants, includingE. tirucalli which was used as a comparison in ecophysiological experiments examining the response ofE. aphylla to drought and temperature.     

Small-spored Alternaria spp. (section Alternaria) are common pathogens on wild tomato species

The wild relatives of modern tomato crops are native to South America. These plants occur in habitats as different as the Andes and the Atacama Desert and are, to some degree, all susceptible to fungal pathogens of the genus Alternaria. Alternaria is a large genus. On tomatoes, several species cause early blight, leaf spots and other diseases. We collected Alternaria-like infection lesions from the leaves of eight wild tomato species from Chile and Peru. Using molecular barcoding markers, we characterized the pathogens. The infection lesions were caused predominantly by small-spored species of Alternaria of the section Alternaria, like A. alternata, but also by Stemphylium spp., Alternaria spp. from the section Ulocladioides and other related species. Morphological observations and an infection assay confirmed this. Comparative genetic diversity analyses show a larger diversity in this wild system than in studies of cultivated Solanum species. As A. alternata has been reported to be an increasing problem in cultivated tomatoes, investigating the evolutionary potential of this pathogen is not only interesting to scientists studying wild plant pathosystems. It could also inform crop protection and breeding programs to be aware of potential epidemics caused by species still confined to South America.     

Three new species of penicillium

Three new species of microfungi belonging to the genus Penicillium Link ex Fries are described and illustrated. All but one have been isolated from the atmosphere of las Palmas, capital city of the island of Gran Canaria (Canary Islands, Spain). They clearly differ from all species of the genus described so far and are, therefore, described and proposed as new species: Penicillium hispanicum sp. nov., Penicillium grancanariae sp. nov., and Penicillium palmensis sp. nov.     

Persistence of immune response in human toxocariasis as measured by ELISA.

The antibody titer was followed in a group of patients, clinically diagnosed with toxocariasis, during a 5 year period. We observed that larvae can survive for at least 5 years in humans. Antigenic stimulation was enough to keep high levels of immunoglobulins over this period. Antibody levels decreased slowly and this pattern is similar to that shown by animal models.     

Mechanisms towards compensation of long-term haemopoietic injury in mice after 5 Gy irradiation:In vivo andin vitro enhancement of superoxide anion production by granulocytes

This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. Anin vivo andin vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes.     

A study on the minimum number of loci required for genetic evaluation using a finite locus model

For a finite locus model, Markov chain Monte Carlo (MCMC) methods can be used to estimate the conditional mean of genotypic values given phenotypes, which is also known as the best predictor (BP). When computationally feasible, this type of genetic prediction provides an elegant solution to the problem of genetic evaluation under non-additive inheritance, especially for crossbred data. Successful application of MCMC methods for genetic evaluation using finite locus models depends, among other factors, on the number of loci assumed in the model. The effect of the assumed number of loci on evaluations obtained by BP was investigated using data simulated with about 100 loci. For several small pedigrees, genetic evaluations obtained by best linear prediction (BLP) were compared to genetic evaluations obtained by BP. For BLP evaluation, used here as the standard of comparison, only the first and second moments of the joint distribution of the genotypic and phenotypic values must be known. These moments were calculated from the gene frequencies and genotypic effects used in the simulation model. BP evaluation requires the complete distribution to be known. For each model used for BP evaluation, the gene frequencies and genotypic effects, which completely specify the required distribution, were derived such that the genotypic mean, the additive variance, and the dominance variance were the same as in the simulation model. For lowly heritable traits, evaluations obtained by BP under models with up to three loci closely matched the evaluations obtained by BLP for both purebred and crossbred data. For highly heritable traits, models with up to six loci were needed to match the evaluations obtained by BLP.