Comparison of sleds versus plankton nets for sampling fish larvae and eggs

Fish larvae and fish eggs were sampled from the inshore waters of eastern Lake Michigan from 1978 through 1980, using a benthic sled and a plankton net towed within 0.5 m of the lake bottom. Differences between estimates of ichthyoplankton abundance based on the benthic sled and those based on the plankton net towed near bottom were examined along with interactions between gear, bottom depth, and time of day. Time of day was determined to be an important factor in comparing these two gear, but data were inconclusive as to the effect of depth on gear differences. Abundance of fish eggs calculated using sled tow data was significantly higher than that for the plankton net. For nighttime collections, density of alewife Alosa pseudoharengus larvae sampled in the plankton net significantly exceeded that for the sled, whereas density of spottail shiner Notropis hudsonius larvae based on sled data was significantly higher than that based on the plankton net for day sampling. Overall, the plankton net appeared to be adequate for sampling abundance of alewife larvae, while the sled was preferred for sampling fish eggs, spottail shiner larvae, and the following less common, but apparently demersal larvae: trout-perch Percopsis omiscomaycus, johnny darter Etheostoma nigrum, ninespine stickleback Pungitius pungitius, and slimy sculpin Cottus cognatus.     

Real-time ultrasound imaging for predicting ovine fetal age

Fetal head width and thoracic depth were observed via real-time ultrasound imaging in 12 single-, 12 twin- and 4 triplet-bearing BooroolaxSouth Australian Merino ewes at weekly intervals during mid pregnancy. Fetal age varied by a maximum of 24 h. Relationships between fetal age and the linear measures (head width, thoracic depth) were determined within litter size categories, using both linear and quadratic terms. All relationships tested for linearity were statistically significant (P<0.05). A curvilinear relationship (P<0.05) was observed for fetal age and thoracic depth of twin fetuses. Significant (P<0.05) curvilinear relationships were also observed for fetal age and head width, and fetal age and thoracic depth when litter size data were pooled. We conclude that head width and thoracic depth are acceptable linear measurements for estimating fetal age in the ovine species. Implications of these results for research and for the commercial field are discussed.     

Degradation of pyrene, benz[a]anthracene, and benzo[a]pyrene by Mycobacterium sp. strain RJGII-135, isolated from a former coal gasification site.

The degradation of three polycyclic aromatic hydrocarbons (PAH), pyrene (PYR), benz[a]anthracene (BAA), and benzo[a]pyrene (BaP), by Mycobacterium sp. strain RJGII-135 was studied. The bacterium was isolated from an abandoned coal gasification site soil by analog enrichment techniques and found to mineralize [14C]PYR. Further degradation studies with PYR showed three metabolites formed by Mycobacterium sp. strain RJGII-135, including 4,5-phenanthrene-dicarboxylic acid not previously isolated, 4-phenanthrene-carboxylic acid, and 4,5-pyrene-dihydrodiol. At least two dihydrodiols, 5,6-BAA-dihydrodiol and 10,11-BAA-dihydrodiol, were confirmed by high-resolution mass spectral and fluorescence analyses as products of the biodegradation of BAA by Mycobacterium sp. strain RJGII-135. Additionally, a cleavage product of BAA was also isolated. Mass spectra and fluorescence data support two different routes for the degradation of BaP by Mycobacterium sp. strain RJGII-135. The 7,8-BaP-dihydrodiol and three cleavage products of BaP, including 4,5-chrysene-dicarboxylic acid and a dihydro-pyrene-carboxylic acid metabolite, have been isolated and identified as degradation products formed by Mycobacterium sp. strain RJGII-135. These latter results represent the first example of the isolation of BaP ring fission products formed by a bacterial isolate. We propose that while this bacterium appears to attack only one site of the PYR molecule, it is capable of degrading different sites of the BAA and BaP molecules, and although the sites of attack may be different, the ability of this bacterium to degrade these PAH is well supported. The proposed pathways for biodegradation of these compounds by this Mycobacterium sp. strain RJGII-135 support the dioxygenase enzymatic processes reported previously for other bacteria. Microorganisms like Mycobacterium sp. strain RJGII-135 will be invaluable in attaining the goal of remediation of sites containing mixtures of these PAH.     

Degradation of Pyrene, Benz[a]anthracene, and Benzo[a]pyrene by Mycobacterium sp. Strain RJGII-135, Isolated from a Former Coal Gasification Site

Volume 62, no. 1, p. 14, column 1, line 20: "250 (mu)g each of yeast extract, peptone, and soluble starch ml(sup-1)" should read "250 (mu)g each of yeast extract, peptone, and soluble starch liter(sup-1)." [This corrects the article on p. 13 in vol. 62.].     

Establishment and immunocharacterization of an immortalized pancreatic cell line derived from the H-2Kb-tsA58 transgenic mouse

Summary This study describes the establishment and characterization of an immortalized cell line derived from the pancreas of an adult H-2K^b-tsA58 transgenic mouse. These cells, designated IMPAN for IMmortalized PANcreatic cells, displayed a cobblestone appearance typical of confluent epithelial cells and a distinct polarity in the organization of their cytoplasmic organelles. Immunocytochemical studies revealed that all IMPAN cells stained positively for a wide range of markers characteristic of pancreatic acinar cells, namely the secretory products α-amylase, chymotrypsinogen, DNAse, the lectinlike secretory protein PAP (pancreatitis associated protein), and the zymogen granule membrane proteins GP-2 and gp300. They also stained positively for carbonic anhydrase II and cytokeratin 19, two proteins characteristic of pancreatic duct cells, as well as for rab3A, a small GTP-binding protein specifically localized in pancreatic islet cells. No reactivity was ever obtained with insulin antibodies. Taken together, these results show that the IMPAN cells exhibit a phenotype comparable to exocrine pancreatic acinar cells. However the expression of some proteins more specific to duct and islet cells make them similar to in vivo or in vitro growing acinar cells. The cell line should be a valuable model to study the mechanisms of growth, differentiation, and transformation of the exocrine pancreatic acinar cell.     

Impairment of systemic concomitant antitumor immunity by excess soluble tumor antigen

Summary Animals bearing a 3-methylcholanthrene induced sarcoma called MC1 rejected substantial numbers of a suspension of the same tumor cells injected IV in comparison with normal rats. The factors that protected the host against lung metastases were impaired by the administration of tumor antigen in the form of irradiated tumor cells or soluble tumor antigen. Animals bearing an MC1 tumor which received either unrelated MC11 irradiated tumor cells or soluble tumor antigen had more lung metastasis than the animals not given any tumor products. However, a statistically significant increase in the number of lung tumor nodules was observed in the rats treated with MC1, compared with those treated with MC11 tumor antigen (soluble tumor antigen or irradiated tumor cells) or no tumor antigen. The increase in the outgrowth of lung tumor nodules in the tumor-bearing host given an excess of tumor materials was produced by a dual mechanism of inhibition of the concomitant immune resistance and nonspecific resistance. The present study shows that soluble tumor antigen similar to material shed from a primary tumor is able to impair concomitant immune resistance to tumor cells within the lungs.     

Cardioprotection by omega-3 fatty acids: Involvement of PKCs?

It has been known since the 1970s that an increased consumption of n-3 long chain polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid has cardioprotective effects. Epidemiological studies have reported that this effect is due to the prevention of the arrhythmias responsible for sudden cardiac death. Mechanistically, different hypotheses have been put forward to give an explanation. Among them, there are a direct effect of the polyunsaturated fatty acids on ion channels and/or a modification of the regulation of ion channels by protein kinase C’s.