A phylogenetic analysis of species in the Bufo crucifer group (Anura: Bufonidae), based on indolealkylamines and proteins from skin secretions

This research tested the utility of two classes of skin secretion compounds to the phylogeny of the Bufo crucifer group. Skin secretions from specimens of nine populations of B. crucifer group were obtained and submitted to qualitative analysis. We observed a clear difference in the composition of the skin secretion molecules obtained from the species of Bufo studied. Fifty-nine molecules, 16 indolealkylamines and 43 proteins, were used as characters, and 39 of these were parsimonious informative. The tree topology of the skin secretion combined data showed areas of congruence and conflict when compared to an mtDNA phylogeny of the B. crucifer group. We used the Templeton test to evaluate the heterogeneity between the skin secretion and mtDNA data. Although not recommended, we performed a combined analysis with the two partitions. The skin secretion characters from the species of Bufo studied have phylogenetic signal. These data are indicative, at least as a preliminary study, of the phylogenetic relationships among the B. crucifer group taxa.     

Proper timing of cytokinesis is regulated by Schizosaccharomyces pombe Etd1

Cytokinesis must be initiated only after chromosomes have been segregated in anaphase and must be terminated once cleavage is completed. We show that the fission yeast protein Etd1 plays a central role in both of these processes. Etd1 activates the guanosine triphosphatase (GTPase) Spg1 to trigger signaling through the septum initiation network (SIN) pathway and onset of cytokinesis. Spg1 is activated in late anaphase when spindle elongation brings spindle pole body (SPB)–localized Spg1 into proximity with its activator Etd1 at cell tips, ensuring that cytokinesis is only initiated when the spindle is fully elongated. Spg1 is active at just one of the two SPBs during cytokinesis. When the actomyosin ring finishes constriction, the SIN triggers disappearance of Etd1 from the half of the cell with active Spg1, which then triggers Spg1 inactivation. Asymmetric activation of Spg1 is crucial for timely inactivation of the SIN. Together, these results suggest a mechanism whereby cell asymmetry is used to monitor cytoplasmic partitioning to turn off cytokinesis signaling.     

Early endosteal bone response to incorporated plutonium-238 in mice

Ten Swiss albino ICR SPF female mice 110 days old (weight about 30 g) were exposed for 48 hours to a solution of plutonium-238 nitrate (spec. act. 5 MBq/1 m1, pH 2.7) injected in amounts of 0.01 ml into the popliteal area of the right femur, each thus receiving about 500 kBq per 30 g body weight. Of the injected activity, 50% was retained in the right femur, 2% in the left femur and approximately 2-3% in the excrements collected separately from each animal during the whole exposure period. Ultrastructurally, electron micrographs revealed a variety of changes, including hypertrophy and destruction of endosteal cell organelles (primary damage), deformation and hypertrophy of osteocytes (secondary damage) and the irregularities in the osteocyte self-burial process leading to an abnormal formation of bone tissue structure (tertiary damage). Qualitatively, these changes in the irradiated bone ultrastructure were analogous to those occurring with age. This was confirmed by comparing two groups of control mice 110 and 330 days old. Assessed quantitatively, changes due to irradiation were more pronounced than those associated with aging.     

Lecithin cholesterol acyltransferase activity in chronic nephropathies

The authors present data from a group of 55 patients suffering from chronic renal diseases. Twenty-two were treated by haemodialysis; the rest had serum creatinine levels ranging from normal to 950 mumol/l. The molar esterification rats [MER] and total cholesterol [TCH] values decreased parallel to the gradual extinction of renal function. A reduced fractional esterification rate [FER] was found in about two thirds of the dialysed patients and in about half of those whose kidney function was still relatively well preserved. It can thus be concluded that reduction of FER values indicative of a disturbance of cholesterol metabolism can already be detected in the early stages of chronic nephropathies.     

The red-crab bloom off the west coast of Baja California, Mexico

Hydroacoustic data indicate that the benthic red crab Pleuroncodesplanipes(Stimpson, 1860) rises from the bottom towards the surfaceat dusk from very compacted patches settled on the continentalshelf. The behaviour is fast and abrupt, lasting >60 min.     

Ichtyotoxic activity of extracts from Mexican marine macroalgae

Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances. This revised version was published online in August 2006 with corrections to the Cover Date.     

A comparison of ferric-chelate reductase and chlorophyll and growth ratios as indices of selection of quince,pear and olive genotypes under iron deficiency stress

Quince (Cydonia oblonga Mill.), pear (Pyrus communis L.) and olive (Olea europaea L.) genotypes were evaluated for their tolerance to iron deficiency stress by growing young plants in three types of aerated nutrient solutions: (1) with iron, (2) without iron or (3) low in iron and with 10 mM bicarbonate. Plants were obtained either from rooted softwood cuttings or from germination of seeds. The degree of tolerance was evaluated with several indices: (1) the chlorophyll content, (2) the root Fe³⁺ reducing capacity and (3) the whole plant relative growth. Fifteen hours before Fe³⁺ reducing capacity determination, iron was applied to the roots of plants with iron-stress, since this method resulted in increasing the reductase activity. All quince and pear genotypes increased the root Fe³⁺ reducing capacity when grown in the treatments for iron-stress, in relation to control plants of the same genotypes. In olive cultivars, the Fe³⁺ reducing capacity was lower in the iron-stress treatments than in the control one. Studying the relationship between relative growth and chlorophyll content for each genotype under iron-stress, in relation to both indices in control plants, a classification of species and genotypes was established. According to that, most olive cultivars and some pear rootstocks and cultivars appear more iron-efficient than quince rootstocks. Our study shows that in some woody species, determining root Fe³⁺ reducing capacity is not the best method to establish tolerance to iron deficiency stress.     

Circadian rhythm of serum and tissue lipids in fed and fasted rats

The oscillations of the free fatty acid concentration in the serum and white (epididymal) adipose tissue, of triglycerides in the serum and liver, of total serum, liver and adrenal cholesterol and of serum phospholipids were studied at 3-hour intervals for a period of 24 hours in fed male Wistar rats and in animals fasted for 24 hours (both adapted to an illumination regimen of 12 hours' light and 12 hours' darkness. The rhythm--studied by means of the cosinor analysis--was present in most of the given parameters; it was not recorded in the liver triglycerides and serum phospholipids of fasted rats and in the adrenal cholesterol of fed animals. Apart from the circadian rhythm, many parameters distinctly displayed an ultradian rhythm, mainly an approximately 12-hour period. In general, one day's starvation did not significantly affect the course of the circadian oscillations of the given indicators of rat lipid metabolism.