Nematode infestation of fillets from Atlantic cod, Gadus morhua, off eastern Canada

The prevalence and intensity of larval nematodes in fillets of Atlantic cod, Gadus morhua, were examined and compared with similar data from a previous survey conducted about 30 yr ago. Anisakis simplex occurred more often in the nape of the fillet, whereas Pseudoterranova decipiens was the predominant species in napeless fillets. The results suggest an increase in both the prevalence and intensity of P. decipiens in fillets of cod, especially those originating from the Gulf of St. Lawrence and coastal Nova Scotia.     

Effects of mot gene expression on the structure of the flagellar motor

Direct freezing procedures have enabled us to visualize distinctive intramembrane particle ring structures in the cytoplasmic membranes of peritrichously flagellated bacteria by means of freeze-fracture electron microscopy. These structures were identified as flagellar motor components because their distribution matched that of flagella, and because they were absent in non-flagellated mutants of Escherichia coli. Particle rings were present in both the Gram-positive Streptococcus and the Gram-negative E. coli. In E. coli, a non-functional mocha operon produced flagellated but immotile cells lacking the particle rings. Simultaneous introduction of the motA and motB genes, led to recovery of both motility and the ring structures but neither gene alone was sufficient. The concomitant loss of the rings and motility is consistent with the ring particles having a central role in the flagellar motor.     

Leucasin, a triterpene saponin from Leucas nutans.

A new saponin, leucasin, has been isolated from Leucas nutans and characterized on the basis of chemical investigation and spectroscopic studies as 3-O-[β- -glucopyranosyl(1→2)β- -glucopyranosyl]2,3β-dihydroxylup-20(29)-ene. Lupeol palmitate, sitosterol and stigmasterol were also isolated.     

The use of the probit model to predict pregnancy status of buffalo based on physio-chemical properties of estrual mucus

Improper timing of artificial insemination with respect to ovulation is one of the major factors hampering the conception rate in buffalo. The present study was an attempt to relate physio-chemical changes in estrual mucus to subsequent pregnancy status in order to find their optimal values for determining the time for artificial insemination (AI). Serum estradiol, total protein and dry matter contents of estrual mucus were evaluated to predict the subsequent pregnancy in 36 buffalo during October 1988 to February 1989. Serum estradiol was determined by radioimmunoassay (RIA); spinnbarkeit, dry matter and total protein were determined by standard methods. Multivariate probit analyses were carried out to relate these variables to subsequent pregnancy status. Elasticity and protein concentration were significantly related to prediction probability of pregnancy status, and they predicted the pregnancy status 86% of the times correctly (P < 0.05). The probability of pregnant animals being correctly classified was 0.76, whereas the corresponding value for non-pregnant animals was 0.95. The present study demonstrated the possibility of using such a statistical model on mucus characteristics for determining proper AI time for better conception rates in Nili-Ravi water buffalo.     

Copper(II) (3,5-diisopropylsalicylate)2 oxidizes thiols to symmetrical disulfides and oxidatively converts mixtures of 5-thio-2-nitrobenzoic acid and nonsymmetrical 5-thio-2-nitrobenzoic acid disulfides to symmetrical disulfides

L-cysteine, D-penicillamine, and L-glutathione were oxidized to symmetrical disulfides in the presence of Cu(II)(3,5-DIPS)2 and air-oxygen at physiologic pH, 7.3. Air-oxygen caused the oxidation of thiol reduced copper, Cu(I), to Cu(II), as evidenced by expected spectrophotometric changes in these reaction mixtures. L-cysteine, D-penicillamine, and L-glutathione formed mixed disulfides and TNB with the addition of DTNB to solutions of these thiols. The observed order of reactivity for these thiols with DTNB was: L-cysteine greater than D-penicillamine greater than L-glutathione. Surprisingly, Cu(II)(3,5-DIPS)2 converted these mixed disulfides to their symmetrical disulfides and DTNB, and although the initial conversion rate was rapid, complete conversion required more than two hours. These observations suggest caution with regard to the spectrophotometric determination of thiols immediately after the addition of Ellman's reagent. These results also clarify an earlier report concerning the oxidation of thiols by Cu(II)(o-phenanthroline)2 and offer caution with regard to the determination of thiols using DTNB in the presence of copper complexes. Spectrophotometric data are provided in support of the suggestion that analysis of plasma or cellular samples for thiols be done in the absence of copper(II) complexes to avoid false negative results.     

Tubulin structure and biochemistry.

In the past year, much has been learned about structure-function correlations in the tubulin molecule, and specifically about the nature and roles of post-translational modifications and tubulin isotypes. The interactions between tubulin and its ligands--both microtubule-associated proteins and anti-mitotic drugs--are becoming clearer at the molecular level.     

Comparison of the carbohydrate composition of rat and human corticosteroid-binding globulin: species specific glycosylation.

We have examined the carbohydrate composition of corticosteroid-binding globulin (CBG) obtained from rat and human serum. Rat CBG contained a carbohydrate composition that was strikingly different from that of human CBG. Like other glycoproteins that circulate in human plasma, human CBG had a carbohydrate composition that was consistent with the presence of biantennary and triantennary oligosaccharide structures. In contrast, the carbohydrate composition of rat CBG indicated the presence of more than one sialic acid residue per antenna. It is not clear whether rat CBG contains a carbohydrate structure with sialic acids attached to both galactose and N-acetylglucosamine on the same antenna, or a terminal disialylated structure (sialic acid linked alpha 2-8 to sialic acid). These structural variations may play a role in the interaction of CBG with its receptor.