The fate of Mus domesticus demes after destruction of their habitats

To test our hypothesis that gene flow has the potential to prevent genetic isolation of crib populations separated by several kilometres, we caught and marked 137 house mice leaving six cribs being emptied of corn. In an attempt to recapture the mice, we set traps just after crib emptying and again, where feasible, 1–2 months later, in areas surrounding cribs (trap-nights/trap-area in hectares:cultivated fields, 3834/29.4; non-cultivated areas, 2238/4). Additional trapping was carried out near nine empty cribs and in eight cultivated fields (3304 trap-nights, 17.7 ha trap-area), each more than 120 m from cribs. After the six cribs were emptied, we recaptured 11% of the crib mice (distance from the crib:mean 81 m, range 0–570 m). In refuge habitats, away from cribs, a breeding population existed and three crib females bred there after emptying of cribs. In demonstrating long dispersal distances and breeding populations away from cribs, our data support the hypothesis that gene flow is potentially large enough to prevent genetic isolation of crib populations separated by expanses of cultivated and uncultivated terrain. The influence of decreased recruitment on gene migration is unclear. Potential predators on nestlings, such as Norway rats, deermice, shrews and voles, escaped from and were trapped outside cribs.     

Elevated CO2 and water deficit effects on photosynthesis, ribulose bisphosphate carboxylase‐oxygenase, and carbohydrate metabolism in rice

Rice (Oryza sativa[L.] cv. IR-72) was grown for a season in sunlit, controlled-environment chambers at 350 or 700 µmol CO₂ mol^?1 under continuously flooded (unstressed) or drought-imposed periods at panicle initiation (stressed). The midday canopy photosynthetic rates (P_n), measured at the CO₂ concentration ([CO₂]) used for growth, were enhanced by high [CO₂] but reduced by drought. High [CO₂] increased P_n by 18 to 34% for the unstressed plants, and 6 to 12% for the stressed plants. In the unstressed plants, CO₂ enrichment increased water-use efficiency (WUE) by 26%, and reduced evapotranspiration (ET) by 8 to 14%. Both high [CO₂] and severe drought decreased the activity and content of ribulose bisphosphate carboxylase-oxygenase (Rubisco). High-CO₂-unstressed plants had 6 to 22% smaller content and 5 to 25%, lower activity of Rubisco than ambient-CO₂-unstressed plants. Under severe drought, reductions of Rubisco were 53 and 27% in activity and 40 and 12% in content, respectively, for ambient- and high-CO₂ treatments. The apparent catalytic turnover rate (K_cat) of midday fully activated Rubisco was not altered by high [CO₂], but severe drought reduced K_cat by 17 to 23%. Chloroplasts of the high-CO₂ leaves contained more, and larger starch grains than those of the ambient CO₂ leaves. High [CO₂] did not affect the leaf sucrose content of unstressed plants. In contrast, severe drought reduced the leaf starch and increased the sucrose content in both CO₂ treatments. The activity of leaf sucrose phosphate synthase of unstressed plants was not affected by high [CO₂], whereas that of ambient-CO₂-grown plants was reduced 45% by severe drought. Reduction in ET and enhancements in both P_n and WUE for rice grown under high [CO₂] helped to delay the adverse effects of severe drought and allowed the stressed plants to assimilate CO₂ for an extra day. Thus, rice grown in the next century may utilize less water, use water more efficiently, and be able to tolerate drought better under some situations.     

A novel E box/AT-rich element is required for muscle-specific expression of the sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene.

The cardiac/slow twitch sarcoplasmic reticulum (SR) Ca2+-ATPase gene (SERCA2 ) encodes a calcium transport pump whose expression is regulated in a tissue- and development-specific manner. Previously we have identified two distinct positive regulatory regions (bp -284 to -72 and -1815 to -1105) as important for SERCA2 promoter activity. Here we demonstrate that the SERCA2 distal promoter region functions like an enhancer by activating a heterologous promoter (TK) in a muscle cell-specific manner. Through deletion analysis a core enhancer region was delimited to the -1467 to -1105 bp fragment. We identified the E box/AT-rich element located at -1115 bp as critical for maximal enhancer activity. Gel mobility shift studies revealed that this E box/AT-rich element specifically binds a protein which is induced during Sol8 myogenesis. This region includes two other cis -acting elements, CArG and MCAT, which also bind specific nuclear protein complexes from Sol8 myotubes. Mutagenesis of each of these sites resulted in decreased SERCA/TK-CAT promoter activity. Based on these data, we propose that the E box/AT-rich element may contribute along with CArG and MCAT elements to the overall activation and regulation of the SERCA2 gene promoter.     

Neurons discovered in male Helicoverpa zea antennae that correlate with pheromone-mediated attraction and interspecific antagonism

Responses of single receptor neurons in the antennae of male Helicoverpa zea to sex pheromone components and to behavioral antagonists were recorded using a cut-sensillum extracellular recording technique. Three types of sensilla were identified from sampling 325 male-specific sensilla trichodea located at the lateral edge of antennomeres. The majority of these sensilla (71%) contained a receptor neuron tuned to the principal sex pheromone component (Z)-11-hexadecenal. A second sensillar type (10%) contained a receptor neuron that responded only to (Z)-9-tetradecenal. A third sensillar type (19%) contained a large-spiking neuron tuned to the secondary pheromone component (Z)-9-hexadecenal, but this neuron also could be stimulated to equivalent spike frequencies by the same emitted amounts of (Z)-9-tetradecenal. A smaller-spiking neuron in this sensillar type responded to two compounds known to act only as behavioral antagonists, (Z)-11-hexadecen-1-ol and (Z)-11-hexadecenyl acetate, and to (Z)-9-tetradecenal. Cross-adaptation studies confirmed the presence of one large- and one small-spiking neuron in the third sensillar type. Dose-response studies correlated to collected stimuli amounts showed that the large-spiking neuron in the third sensillar type was equally tuned to (Z)-9-hexadecenal and (Z)-9-tetradecenal, whereas the smaller-spiking neuron was far more sensitive to (Z)-11-hexadecen-1-ol and to (Z)-11-hexadecenyl acetate than to (Z)-9-tetradecenal. Accepted: 29 September 1997     

Iatrogenic Osteomalacia and Myopathy due to Phosphate Depletion

In a patient receiving regular dialysis prolonged hypophosphataemia due to aluminium hydroxide therapy resulted in osteomalacia and severe proximal myopathy. Both osteomalacia and myopathy responded to correction of hypophosphataemia without vitamin D therapy.     

Enhancement of UDP-galactose:mucin galactosyltransferase activity by spermine

A microsomal preparation prepared from the mucosal lining of canine trachea catalyzed the transfer of galactose from its uridine diphosphate derivative to sialidase-treated ovine submaxillary mucin. Maximal incorporation occurred at 30 mm mn²⁺. When the concentration of mn²⁺ in the reaction mixture was reduced to 2.5 mm, approximately two-thirds of the enzymatic activity was lost, but full activity could be restored by the addition of 1 mm spermine. Under these conditions spermine did not affect the K_m for UDP-galactose, but lowered the K_m for sialidase-treated ovine submaxillary mucin and Mn²⁺ by a factor of 10. The effect of spermine was abolished with increasing concentrations of Mn²⁺, and in the absence of the metal, enzymatic activity was lost and could not be restored by the addition of spermine. Spermidine also stimulated activity at low levels of Mn²⁺, but to a lesser degree than spermine. A slight stimulatory effect was consistently derived from putrescine as well, while cadaverine, putreanine, and monoamines were ineffectual. Spermine had a similar effect on the enzymatic transfer of GalNAc to a protein core acceptor but had little or no effect on the enzymatic transfer of sialic acid to sialidase-treated ovine submaxillary mucin, galactose to N-acetylglucosamine, or fucose to sialidase-galactosidase-treated fetuin. Similar results were obtained with enzyme preparations prepared from canine submaxillary glands. Other polycationic compounds such as protamine, histone, and polylysine also stimulated enzymatic activity at suboptimal concentrations of mn²⁺.