Growth of the clupeid fishes, Stolothrissa tanganicae and Limnothrissa miodon, in the Zambian waters of Lake Tanganyika

The age and growth of two endemic Lake Tanganyikan clupeid fishes, Stolothrissa tanganicae and Limnothrissa miodon , were estimated from analysis of otolith microstructure in specimens collected in Zambian waters from October to December 1990. Both species had relatively clear, concentric otolith increments which were believed to represent daily increments based on their similarity to daily increments found in some marine clupeid species. The growth rates estimated from length-at-age data were: for S. tanganicae, L_t = 104·0 (1 – exp (– 0.00512 ( t – 5·8))); for L. miodon, L_t = 155.4 (1 – exp (– 0.00236 ( t +8.1))). In most cases, the growth parameters obtained from otolith analyses generally agreed with those previously estimated from analyses of length-frequency distributions.     

Incorporation of trace elements from environment into the hair structure

A model describing the incorporation of trace elements from environment into the hair structure is presented. Model predictions for radial and longitudinal concentration profiles are given. Comparison with elemental data is satisfactory.     

Life history of the cownose ray, <Emphasis Type="Italic">Rhinoptera bonasus</Emphasis>, in the northern Gulf of Mexico,with comments on geographic variability in life history traits

Synopsis We determined age and growth, size at maturity, and fecundity for cownose rays, Rhinoptera bonasus, collected from the northern Gulf of Mexico. Vertebral age estimates ranged from 0+ to 18+ years for females and 0+ to 16+ years for males. Annual deposition of growth increments was verified with marginal increment analysis. Likelihood ratio tests indicated that the growth of the cownose ray was best described by a combined sexes Gompertz model. Median size at 50% maturity was determined to be 642 mm DW for males and 653 mm DW for females, or 4–5 years of age. Median pup size-at-birth was estimated to be 350 mm DW, with a gestation period of 11–12 months. In all cases, gravid females contained only one pup. Statistically significant differences were detected between growth curves for the Gulf of Mexico and the western Atlantic Ocean. Cownose rays in the Gulf of Mexico had lower estimates of DW_∞ and K, and a higher theoretical longevity than their conspecifics in the western Atlantic Ocean. Cownose rays in the Gulf of Mexico also attain maturity at a smaller size and earlier age than their counterparts in the western Atlantic Ocean.     

Coronatine biosynthesis: Incorporation of l-[U-14C]isoleucine and l-[U-14C] threonine into the 1-amido-1-carboxy-2-ethylcyclopropyl moiety

Addition of either l-[U-¹⁴C]threonine or l-[U-¹⁴C]isoleucine to 2.7-day-old shaking liquid cultures of Pseudomonas syringae pv. atropurpurea resulted in incorporation of radioactivity into coronatine, but not into N- coronafacoylvaline, another phytotoxin excreted by P.s. atropurpurea. In contrast, addition ofl-[U-¹⁴C]valine did not lead to incorporation of radioactivity into coronatine, but instead into coronafacoylvaline. Acid hydrolysis of the purified [¹⁴C] coronatine obtained after incorporation of either [¹⁴C]isoleucine or [¹⁴C]threonine demonstrated that > 94% of the radioactivity was present in the 1-amido-1-carboxy-2-ethylcyclopropyl moiety of coronatine, and < 6 % was in the coronafacoyl moiety. These findings are used to propose a biosynthetic pathway for coronatine.     

Selective Protection by Uridine of Growth Inhibition by 5-Fluorouracil (5FU) Mediated by 5FU Incorporation into RNA,But Not the Thymidylate Synthase Mediated Growth Inhibition by 5FU-Leucovorin

Fluorouracil (5FU) acts by RNA-incorporation and inhibition of thymidylate synthase; the first action is counteracted by uridine, and the second is enhanced by leucovorin (LV). Growth inhibition of C26-10 colon cancer cells by 5FU was enhanced by LV and rescued by uridine, but 5FU-LV was only partially rescued by uridine. In WiDr cells, 5FU sensitivity was not enhanced by LV, while both 5FU and 5FU-LV were rescued by uridine. Intermediate trends were found in SW948 and HT29 cells. Uridine rescue in mice allowed 1.5-fold increase in 5FU dose, leading to 2-fold increase in the antitumor effect and thymidylate synthase inhibition in resistant Colon-26 tumors. In the sensitive Colon-26-10 tumor, uridine rescue decreased 5FU-RNA incorporation > 10-fold, without affecting the antitumor activity. The use of LV and uridine can differentiate between two mechanisms of action of 5FU.     

Otolith microstructure and daily age of Anguilla japonica, Temminck & Schlegel elvers from the estuaries of Taiwan with reference to unit stock and larval migration

To test the hypothesis that the Japanese eel, Anguillu japonica , elvers in the eastern and western coasts of Taiwan are recruited from two different spawning grounds and to increase the knowledge of the early life history of the eel, the otolith microstructure and daily age of elvers collected from five estuaries in the coast of Taiwan during December 1989 through February 1990 were examined by scanning electron microscopy. The total length of elvers at arrival in the estuaries was similar among estuaries, averaging c . 56.0 mm and showed a seasonal decrease. The maximum radius of the sagittal otolith of elvers ranged from 124.46 to 181.82μm with a mean of 143.15 ± 12.72 μm. The otolith from centre to edge included an organic-rich primordium (9.20 ± 2.02 μm in diameter), a diffusively calcified core (20.94 ± 1.99 μm), and the daily growth increments; these three layers were probably deposited during the embryonic, yolk sac and feeding period respectively. The growth rate of the otolith was higher at the beginning of early life (0.5−1.0 μm day ⁻¹), lowest at approximately 100-days old (<0.5 μm day⁻¹), and highest 1 month before arrival at the estuary (> 1.0 pm day⁻¹). The mean age for elvers arriving in the estuaries of the coasts of Taiwan was approximately 170.4 ± 21.02 days. Neither the growth pattern of the otolith nor the age of elvers arriving in the estuary were significantly different among estuaries, indicating that the elvers in both eastern and western Taiwan were probably recruited from the same spawning ground. The growth pattern of the otolith in relation to larval migration was analysed.     

Incorporation of the gene for a cell-cell channel protein into transformed cells leads to normalization of growth

Summary Incorporation of the gene for connexin 43, a cell-cell channel protein of gap junction, into the genome of communication-deficient transformed mouse 10T1/2 cells restored junctional communication and inhibited growth. Growth was slowed, saturation density reduced and focus formation suppressed, and these effects were contingent on overexpression of the exogenous gene and the consequent enhancement of communication. In coculture with normal cells the growth of the connexin overexpressors was completely arrested, as these cells established strong communication with the normal ones. Thus, in culture by themselves or in coculture, the connexin overexpressor cells grew like normal cells. These results demonstrate that the cell-cell channel is instrumental in growth control; they are the expected behavior if the channel transmits cytoplasmic growth-regulatory signals.