Some aspects of the biology of the red bass, Lutjanus bohar (Forsskal), from the Tigak Islands, Papua New Guinea

The growth rate, food, reproduction and mortality rates of the red bass, Lutjanus bohar , are described for fish associated with coral reefs in the Tigak Islands of Papua New Guinea. Spawning intensity by month was investigated by examination of gonad maturation stages. The length–at–maturity of female L. bohar was estimated from the relationship between changes in gonad index with increasing size. Female fish matured at about 45–0 cm fork length. The Petersen method was used to obtain age–at–length data from length frequency data of L. bohar captured by hook–and–line fishing. The growth of L. bohar was described by a von Bertalanffy growth curve with the parameters AT=0.27 and L_∞ = 81.7 cm. There was a positive correlation between water depth (D) and the length of L. bohar (L) that was described by L = 318–8+ 3.050 D . The mortality rates ( Z ) of L. bohar from shallow (≤30m) and deep (≤80m) water were estimated from length converted catch curves and were 1–181 and 0–64 respectively. The high Z value for the shallow water population of L. bohar was ascribed to the migration of larger specimens into deeper water. The deep water population of L. bohar remains unfished and the estimate of Z was believed to be equivalent to the natural mortality rate ( M ). An empirical method of calculating M gave an estimate of 0.59. Lutjanus bohar is a carnivorous piscivore that feeds throughout the water column.     

1H-15N heteronuclear NMR studies of Escherichia coli thioredoxin in samples isotopically labeled by residue type

Ten samples of Escherichia coli thioredoxin were individually isotopically enriched by residue type via growth of an appropriate auxotrophic strain on media supplemented with one 2H, 15N-enriched amino acid. 1H observe-heteronuclear decoupling experiments were conducted on these samples making use of the 95-Hz 1H-15N amide J1 coupling. Subtraction of near-resonance from off-resonance 15N decoupled spectra generated difference patterns corresponding only to protons directly bonded to 15N nuclei. For the ten different enriched residue types observed to date, every labeled position (60) has been observed as a resolved resonance. The spectral dispersion in both the 1H and the 15N dimensions was roughly 1500 Hz (at 500-MHz field strength) with rather little apparent dependence on residue type. With the exception of the glycine-enriched sample, the range of the J1 coupling constants was not much greater than the precision of the measurements (1.5-2.0 Hz). However, for the glycine residues the J1 amide coupling values varied over a range of 10 Hz.     

Rapid determination of DNA synthesis in adherent cells grown in microtiter plates

A specific, rapid, and economical method for measuring the extent of DNA synthesis in adherent rat hepatoma H4-II-E cells grown in 96-well microtiter plates is described. The adherent cells were pulsed for 1 h with [methyl-3H]thymidine, released from the substratum by trypsinization, and collected on fiberglass filters with a MASH II cell harvester. The amount of radioactivity incorporated was directly proportional to the number of cells per well. Growth curves generated by measuring [methyl-3H]thymidine incorporation and counting the number of cells per well were identical. Experiments with inhibitors of DNA, protein, and RNA synthesis demonstrated that this method selectively measured DNA synthesis. In addition, [3H]thymidine uptake showed excellent correlation with autoradiographic assessment of DNA synthesis. This specific and sensitive method for determining DNA synthesis in microtiter cultures should facilitate studies of effects of various growth-controlling agents on epithelial, fibroblastic, and other cells which grow as adherent cells in culture.     

Chemically induced vasospasm: the effect of ischemia, vessel occlusion, and adrenergic blockade

Vasospasm in revascularized tissue can compromise tissue perfusion even though the microsurgical anastomoses remain patent. Circulating catecholamine stimulates peripheral vasoconstriction. Chemical vasospasm was induced by the intraarterial administration of norepinephrine to denervated rat hind limbs. Heel pad blood flow was assessed by laser-Doppler velocimetry. Mean blood flow was 463 +/- 106 in the denervated leg and 337 +/- 50 in the opposite (intact) leg (p less than 0.01). Flow in the denervated leg decreased 78 percent (463 +/- 106 to 100 +/- 23) within 5 minutes of norepinephrine administration and did not return to normal for 30 minutes. Norepinephrine administration in the presence of 1 and 3 hours of ischemia decreased flow at 5 minutes to 6.6 and 6.0 percent of normal, respectively (31 +/- 14, 28 +/- 14, control 100 +/- 23; p less than 0.001). Administration of intraarterial norepinephrine distal to a femoral artery occluded for 1 and 5 minutes reduced flow following clamp release to 11.2 and 7.1 percent of normal 5 minutes after clamp release (52 +/- 9, 33 +/- 7, control 100 +/- 23; p less than 0.001). Comparison of the 1-minute and 5-minute groups to each other showed a significant flow decrease in the 5-minute group (p less than 0.007). This indicates that the observed decrease in flow was related both to the presence of a vessel occlusion and to the length of the occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biology and defensive adaptations in Rodatus major (Coleoptera: Coccinellidae) and its prey, Monophlebulus pilosior (Hemiptera: Margarodidae)

The biology of the Australian coccinellid Rodatus major (Blackburn) and its prey, the hemipteran margarodid Monophlebulus pilosior (Maskell), are described. New predators and a new parasite of M. pilosior are recorded. Rodatus major makes use of elaborate and distinctive defensive adaptations and behaviour to protect itself from predators. They include cryptic coloration, aposematic behaviour, production of wax by larvae, production of a large, thick protective covering concealing the pupa and resembling an M. pilosior ovisac, and reflex bleeding. It is the only known coccinellid species in which both prepupa and pupa are hidden by a protective shroud of wax threads. Rodatus major has a specialized feeding behaviour. Its potential as a biological control agent is assessed. It is only the second Australian margarodid-feeding coccinellid to be studied, Rodolia cardinalis (Mulsant) being the first.     

Response of end bud cells from immature rat mammary gland to hormones when cultured in collagen gel

End buds from 4- to 5-week-old rat mammary glands were isolated and cultured within a rat tail tendon collagen gel matrix. Media containing equine serum or porcine serum and cholera toxin promoted growth, but not the production of casein or thioesterase II, nor did they induce a state of differentiation as assessed by cell ultrastructure. Medium supplemented with only 5% porcine serum, insulin and cholera toxin did not support growth or differentiation. However, when prolactin, estradiol, progesterone and hydrocortisone were added to this medium, growth was stimulated greatly and a differentiated state was induced as assessed by the production of casein and thioesterase and by the appearance of a highly secretory ultrastructure.