Temperature and starvation affect the hemolymph acid-base balance of the xeric yellow scorpion,Leiurus quinquestriatus

Summary Water conservation is crucial for terrestrial animals such as scorpions which generally live in xeric habitats. One route of water loss is evaporation from their book lungs. In order to save water, scorpions may have a high resistance to gas exchange with the environment. If this is so then the partial pressure of CO₂ in their hemolymph, PCO₂, must be high. Does this affect their acid-base balance? Hemolymph PCO₂ and pH in normally-fed or starved desert-dwelling yellow scorpions Leiurus quinquestriatus were studied in vivo as functions of temperature. An ambient temperature increase (lasting at least 3 days) resulted in a rise of PCO₂ and a fall of pH, with thermal coefficients of 1.6 Torr · °C^-1 and-0.016 pH unit · °C^-1, respectively. The thermal coefficients for cell-free hemolymph studied in vitro were the same. At 28 °C, 3–6 weeks of starvation led to a 4.8 Torr increase in PCO₂ and a 0.056 unit decrease in pH. The in vivo PCO₂ values are among the highest, and pH values are the lowest of the terrestrial arthropods studied so far, e.g., at 28 °C they are 29 Torr and 7.15 pH respectively. It is argued that this particular acid-base balance with a marked hypercapnia is typical of a successful xeric air-breathing animal.Abbreviations ABB acid-base balance - PCO₂ partial pressure of CO₂ - PO₂ partial pressure of O₂     

Coexistence of NADPH-diaphorase with vasopressin and oxytocin in the hypothalamic magnocellular neurosecretory nuclei of the rat

Coexistence of NADPH-diaphorase with vasopressin and oxytocin was studied in the magnocellular neurosecretory nuclei of the rat hypothalamus by use of sequential histochemical and immunocytochemical techniques in the same sections. Coexistence was found in all the nuclei examined (supraoptic, paraventricular, circular, fornical, and in some isolated neurons located in the hypothalamic area between the paraventricular and supraoptic nuclei). The ratios of neurons expressing both markers (NADPH-diaphorase and vasopressin, NADPH-diaphorase and oxytocin) in each of the nuclei were very similar. Although further studies must be carried out, the partial coexistence found in all nuclei suggests that NADPH-diaphorase is probably not related to general mechanisms involving vasopressin and oxytocin, but rather in specific functions shared by certain hypothalamic neuronal cell populations.     

Primary central nervous system lymphomas in immunocompetent patients

Primary Central nervous system lymphoma is a rare non-Hodgkin's tumor of the brain that has been traditionally found in patients with immunodeficiency syndromes. However, there are several immunocompetent patients that have also been reported with this neoplasm. In this group of patients, the mean age of diagnosis is around 60-year old, with a very slight predominance in women. Macroscopically, most of the tumors are unique and mainly located in the supratentorial region in the proximity of the cerebrospinal fluid circulation. The typical histological pattern is a perivascular distribution of tumor cells, within a network of reticulin fibers. Even though they are usually well defined masses, it is not rare to find tumor invasion beyond the macroscopic margin. Coagulative necrosis is not as common as in immunodeficiency-related cases. Immunohistochemistry has demonstrated that most of the tumor cells are B-lymphocytes and the electron microscopic findings do not differ from those reported in systemic non-Hodgkin's lymphomas. There are several histological classifications of these tumors, some of them with recent modifications to facilitate the analysis, but unfortunately, up now with a little or no clinical significance. The diagnosis is based on the histological study of the specimen obtained mainly through a Stereotactic biopsy. The treatment is based on a combination of chemotherapy followed by radiotherapy, but the mortality rate is still high.     

Reproducible infection of intact Aotus lemurinus griseimembra monkeys by Plasmodium falciparum sporozoite inoculation

Aotus lemurinus griseimembra is considered one of the best nonhuman primate species for malarial studies because of its susceptibility to infection by Plasmodium falciparum asexual blood stages. However, reproducible transmission of infective P. falciparum sporozoites by mosquito inoculation has been difficult to achieve even in splenectomized monkeys. Characterization of an Aotus-P. falciparum cyclical transmission model has become a top priority as a result of the significant progress toward the development of preerythrocytic malaria vaccines. Herein, we describe a reproducible model developed using intact A. lemurinus griseimembra monkeys intravenously inoculated with sporozoites from a monkey-adapted P. falciparum (Santa Lucia) strain and a wild Falciparum-Cali-Colombia-4 (FCC-4) strain. Sporozoites were obtained by salivary gland dissection of laboratory-reared Anopheles albimanus mosquitoes. Parasitemia was monitored by thick-smear microscopy, parasite lactate dehydrogenase (pLDH) determination, and mosquito xenodiagnosis. The last method proved to be the most sensitive method for monitoring parasitemias. Infection with the Santa Lucia strain showed a mean prepatent period of 16 days (range 6-21 days), whereas infection with the wild FCC-4 strain resulted in a 24-day prepatent period. Mean peak parasite density was approximately 900 parasites/microliter for both parasite strains. The prepatent period, the peak of parasitemia, and the duration of patency were independent of the size of the sporozoite inoculum and the presence of spleen in the host. This model is being successfully used to test the protective efficacy of P. falciparum preerythrocytic vaccine candidates.     

Oleate, linoleate and cholesterol differently modify aspartyl- and glutamyl-aminopeptidase activities in primary cultures of rat astrocytes

The intake of mono- and polyunsaturated fatty acids has been associated with a minor risk of cardiovascular diseases including hypertension. Changes in levels of fatty acids may also modify the cell activity and may be related with alterations in different regulatory processes. Aminopeptidases are zinc-metalloenzymes which metabolise circulating peptide hormones in several tissues. Glutamyl-aminopeptidase (GluAP) and to a lesser extent, aspartyl-aminopeptidase (AspAP), are related with angiotensin metabolism in the renin-angiotensin system. The present work was designed to study the effect of a range of concentrations (1-100 microM) of oleic and linoleic acids and cholesterol present in the culture medium on the activity of GluAP and AspAP in the culture of rat cerebral cortical astrocytes taken from 21-day-old fetuses. The results showed that oleic acid inhibits, while linoleic acid stimulates the activity of AspAP. Both fatty acids inhibit the activity of GluAP. Cholesterol stimulates the activity of both enzymes. On the basis of these results, a functional link may exit between the effects of fatty acids on hypertension and the modulation of aminopeptidase activity by these compounds in rat astrocytes, as an example of target cell type in the central nervous system.     

Gas exchange and energy metabolism of the ostrich (Struthio camelus) embryo

We measured oxygen consumption ( ) and carbon dioxide emission ( ) rates, air-cell gas partial pressures of oxygen (P_AO₂) and CO₂ (P_ACO₂), eggshell water vapour conductance and energy content of the ostrich (Struthio camelus) egg, ‘true hatchling’ and residual yolk, and calculated RQ and total oxygen consumption ( ) for ostrich eggs incubated at 36.5°C and 25% relative humidity. The pattern showed a drop of approximately 5% before internal pipping. just prior to internal pipping agrees with allometric calculations. Despite the higher incubation temperature compared to other studies, and the resultant shorter incubation duration (42 days), (91.7 l kg⁻¹) was similar to a previously reported value. RQ values during the second half of incubation (approx. 0.68) were lower than expected for lipid catabolism. Prior to internal pipping, P_AO₂ and P_ACO₂ were 98 and 48.3 torr (13.1 and 6.4 kPa), respectively. The growth pattern of the ostrich embryo is different from the typical precocial pattern, showing a time delay in the rapid growth phase. As a result, the lowered overall energy expenditure for tissue maintenance, as compared to other species, is reflected in the low yolk utilization and high residual yolk fraction of the whole hatchling dry mass. These could also result from the relatively short incubation period of the ostrich egg, thereby evading desiccation by excess water loss.     

Bacterial phylotypes associated with the digestive tract of the sea urchin Paracentrotus lividus and the ascidian <Emphasis Type="Italic">Microcosmus</Emphasis> sp.

We used sequencing and phylogenetic analysis of PCR-amplified 16S rRNA genes from bacteria that are associated with the esophagus/pharynx, stomach and intestine of two marine sympatric invertebrates but with different feeding mechanisms, namely the sea urchin Paracentrotus lividus (grazer) and the ascidian Microcomus sp. (suspension feeder). Amplifiable DNA was retrieved from all sections except the pharynx of the ascidian. Based on the inferred phylogeny of the retrieved sequences, the sea urchin’s esophagus is mainly characterized mostly by bacteria belonging to α-, γ-Proteobacteria and Bacteriodetes, most probably originating from the surrounding environment. The stomach revealed phylotypes that belonged to γ- and δ-Proteobacteria, Verrucomicrobia and Fusobacteria. Since the majority of their closest relatives are anaerobic species and they could be putative symbionts of the P. lividus stomach, in which anaerobic conditions also prevail. Seven out of eight phylotypes found in the sea urchin’s intestine belonged to sulfate reducing δ-Proteobacteria, and one to γ-Proteobacteria, with possible nutritional activities, i.e. degradation of complex organic compounds which is beneficial for the animal. The bacterial phylotypes of the ascidian digestive tract belonged only to the phyla of Actinobacteria and Proteobacteria. The stomach phylotypes of the ascidian were related to pathogenic bacteria possibly originating from the water column, while the intestine seemed to harbour putative symbiotic bacteria that are involved in the degradation of nitrogenous and other organic compounds, thus assisting ascidian nutrition. The text was submitted by the authors in English.