Chlamydosporol,a new metabolite from Fusarium chlamydosporum

Extracts of rice on which an isolate of Fusarium chlamydosporum had been cultured were toxic to brine shrimps. The toxic fraction was purified by flash chromatography to give two compounds which were identified by UV, IR, NMR and mass spectroscopy at the 6 and 6 isomers of 5-hydroxy-4-methoxy-6, 8a-dimethyl-6,7-dihydro-2H,8aH-pyrano[2,3-b]pyran-2-one. These lactones for which the name chlamydosporol is proposed have not been reported previously. When tested in brine shrimp and HeLa cell assays, the LC₅₀ concentration for a mixture of the isomers was approximately 400 g/ml in both systems.     

The chicken dystrophin cDNA: striking conservation of the C-terminal coding and 3'' untranslated regions between man and chicken.

Dystrophin is a very large muscle protein (approximately 400 kd) the deficiency of which is responsible for Duchenne muscular dystrophy. Its function is unknown at present. In order to know whether different domains of the protein are differentially conserved during evolution, we have cloned and sequenced the chicken dystrophin cDNA. The protein coding sequence has almost the same size as in man. The N-terminal region that resembles the actin binding domain of alpha actinin, as well as the large spectrin like domain show 80% and 75% conservation respectively between chicken and man. In contrast, the C-terminal region shows 95% identity over 627 aa suggesting that it is an important region of interaction with other proteins. Comparison of the amino acid sequence of this C-terminal region to other protein sequences shows only marginally significant similarities. Finally we have found a striking conservation of three segments of the 3' untranslated sequence (85% homology over a total of 920 nt) between chicken and man. These also appear to be conserved in other mammals. This high conservation is not linked to open reading frames.     

On the evolutionary ecology of marking pheromones

Summary Many parasitic insects mark hosts with a pheromone after oviposition. The evolutionary ecology of such marking pheromones was studied to determine (i) under what ecological and behavioral conditions such pheromones could evolve and (ii) why so many of these marking pheromones are water-soluble and thus short-lived. We used a number of different techniques. First, the fitness values of individual normal (nonmarking) and mutant (marking) insects foraging for hosts were computed using dynamic state-variable models. Second, population level models were used to study when a population of non-marking individuals can be invaded by marking individuals. Third, behavior-rich simulations (developed originally for apple maggot,Rhagoletis pomonella) were used to test experimentally some of the hypotheses generated using the individual and population-level models. Finally, we developed a model for the benefit over time to an individual by marking. This model shows that when benefit is measured in terms of larval survival, nearly all of the benefit to a mother is obtained from short-lived marks. Genetical theories of pheromone evolution and the connection between our results and existing theories of altruistic behavior are discussed.     

Monoclonal antibodies to a fern spermatozoid detect novel components of the mitotic and cytokinetic apparatus in higher plant cells

Summary The aim of this study was to search for uncharacterized components of the plant cytoskeleton using monoclonal antibodies raised against spermatozoids of the fernPteridium (Marc et al. 1988). The cellular distribution of crossreacting immunoreactive material during the division cycle in wheat root tip cells was determined by immunofluorescence microscopy and compared to the fluorescence pattern obtained with antitubulin. Five antibodies are of special interest. Pas1D3 and Pas5F4 detect a diffuse cytoplasmic material, which, during mitosis, follows the distribution of microtubules (MTs) at the nuclear surface and in the preprophase band (PPB), spindle and phragmoplast. The immunoreactive material codistributes specifically with MT arrays of the mitotic apparatus and does not associate with interphase cortical MTs. Pas5D8 is relevant to the PPB and spatial control of cytokinesis. It binds in a thin layer at the cytoplasmic surface throughout the cell cycle, except when its coverage is transiently interrupted by an exclusion zone at the PPB site and later at the same site when the phragmoplast fuses with the parental cell wall.Pas2G6 reacts with a component of basal bodies and the flagellar band in thePteridium spermatozoid and recognizes irregularly shaped cytoplasmic vesicles in wheat cells. During interphase these particles form a cortical network.Pas6D7 binds to dictyosomes and dictyosome vesicles. At anaphase the vesicles accumulate at the equator and subsequently condense into the cell plate.Abbreviations MT microtubule - PPB preprophase band     

Low VA/Q areas: arterial-alveolar N2 difference and multiple inert gas elimination technique

In 16 critically ill patients the arterial-alveolar N2 difference and data from the multiple inert gas elimination technique (MIGET) were compared in the evaluation of the contribution of low alveolar ventilation-perfusion ratio (VA/Q) lung regions (0.005 less than VA/Q less than 0.1) to venous admixture (Qva/QT). The arterial-alveolar N2 difference was determined using a manometric technique for the measurement of the arterial N2 partial pressure (PN2). We adopted a two-compartment model of the lung, one compartment having a VA/Q of approximately 1, the other being open, gas filled, unventilated (VA/Q = 0), and in equilibrium with the mixed venous blood. This theoretical single compartment represents all lung regions responsible for the arterial-alveolar N2 difference. The fractional blood flow to this compartment was calculated using an appropriate mixing equation (Q0/QT). There was a weak but significant relationship between Q0/QT and the perfusion fraction to lung regions with low VA/Q (0.005 less than VA/Q less than 0.1) (r = 0.542, P less than 0.05) and a close relationship between Q0/QT and the perfusion fraction to lung regions with VA/Q ratios less than 0.9 (r = 0.862, P less than 0.001) as obtained from MIGET. The difference Qva/QT-Q0/QT yielded a close estimation of the MIGET right-to-left shunt (Qs/QT) (r = 0.962, P less than 0.001). We conclude that the assessment of the arterial-alveolar N2 difference and Q0/QT does not yield a quantitative estimation of the contribution of pathologically low VA/Q areas to QVa/QT because these parameters reflect an unknown combination of pathological and normal (0.1 less than VA/Q less than 0.9) gas exchange units.(ABSTRACT TRUNCATED AT 250 WORDS)     

The intron 7 donor splice site transition: a second Tay-Sachs disease mutation in French Canada

Mutations at the hexosaminidase A (HEXA) gene which cause Tay-Sachs disease (TSD) have elevated frequency in the Ashkenazi Jewish and French-Canadian populations. We report a novel TSD allele in the French-Canadian population associated with the infantile form of the disease. The mutation, a GA transition at the +1 position of intron 7, abolishes the donor splice site. Cultured human fibroblasts from a compound heterozygote for this transition (and for a deletion mutation) produce no detectable HEXA mRNA. The intron 7+1 mutation occurs in the base adjacent to the site of the adult-onset TSD mutation (G805A). In both mutations a restriction site for the endonuclease EcoRII is abolished. Unambiguous diagnosis, therefore, requires allele-specific oligonucleotide hybridization to distinguish between these two mutant alleles. The intron 7+1 mutation has been detected in three unrelated families. Obligate heterozygotes for the intron 7+1 mutation were born in the Saguenay-Lac-St-Jean region of Quebec. The most recent ancestors common to obligate carriers of this mutation were from the Charlevoix region of the province of Quebec. This mutation thus has a different geographic centre of diffusion and is probably less common than the exon 1 deletion TSD mutation in French Canadians. Neither mutation has been detected in France, the ancestral homeland of French Canada.     

A minority of 46,XX true hermaphrodites are positive for the Y-DNA sequence including SRY

Summary A total of 30 cases of 46,XX true hermaphroditism was analysed for Y-DNA sequences including the recently cloned gene for male testis-determination SRY. In 3 cases, a portion of the Y chromosome including SRY was present and, in 2 cases, was localised, to Xp22 by in situ hybridisation. Since previous studies have shown that the majority of XX males are generated by an X-Y chromosomal interchange, the Xp22 position of the Yp material suggests that certain cases of hermaphroditism can arise by the same meiotic event. The phenotype in the 3 SRY-positive cases may be caused by X-inactivation resulting in somatic mosaicism of testis-determining factor expression giving rise to both testicular and ovarian tissues. Autosomal or X-linked mutation(s) elsewhere in the sex-determining pathway may explain the phenotype observed in the remaining 27 SRY-negative cases.     

Increased preproenkephalin A gene expression in the rat heart after induction of a myocardial infarction.

The expression of preproenkephalin A (ppENK) gene was investigated in the rat heart, following the onset of myocardial infarction induced by ligation of the left anterior descending coronary artery. The relative abundance of ppENK mRNA and the level of enkephalins were measured by Northern blot analysis and radioimmunoassay, respectively, in the ventricles from control-unoperated, sham-operated, and operated rats. Three hours after the surgery, a comparison between rats with infarction and sham-operated rats revealed that the relative abundance of ppENK mRNA and the level of enkephalins were increased three- to four- and two- to three-fold, respectively, in the ventricles of rats with infarction. No difference was observed between rats with infarction and sham-operated rats 24 h after the surgery, or between rats with infarction compared at time intervals of 3 and 24 h following the surgery. The abundance of the ppENK mRNA in the polysomal fraction of the ventricular septum was also measured 3 h after the surgery and found to be threefold higher in rats with infarction as compared with sham-operated rats. These results indicate that the level of enkephalins rapidly increases in the ventricles of rats following myocardial infarction, and that this higher level may be ascribed to a stimulation of the local synthesis of enkephalins.