k-Casein gene frequencies support subdivision and historical origin of Argentine Creole cattle

Gene frequencies at the k-casein locus were estimated in six different herds (N = 180) of Argentinean Creole cattle. The results showed a strong influence of subdivision and independent evolution on the divergence of the observed gene frequencies. These results suggest that the population structure of these herds favor the maintenance of polymorphism, which is of crucial importance for the long-time survival of populations.

Genetic variability in salt tolerance during germination of Stylosanthes humilis H.B.K. and association between salt tolerance and isozymes

Variation in salt tolerance of six natural populations of Stylosanthes humilis from three ecogeographic regions, Mata (wet tropical climate), Agreste and Sert��o (semi-arid tropical climate) of Pernambuco State, Northeast Brazil, was evaluated on germination in 201 mM NaCl. There were significant differences among families of all populations for germination percentage and of five populations (except Tamandar��, from Mata) for germination rate. Populations from semi-arid regions presented high coefficients of genetic variation, those from Agreste being higher than those from Sert��o. Populations from Mata showed low coefficients of genetic variation. The coefficients of genotypic determination were high for five populations, except Tamandar��, both for germination percentage ( > or = 0.89) and for germination rate ( > or = 0.79), indicating the possibility of selection for salt tolerance in these populations. An electrophoretic analysis of esterase and peroxidase isozymes was also performed in the six populations, and correlations were estimated between salt tolerance and allelic frequencies. The analysis of salt tolerant and salt sensitive families of populations from Agreste suggested an association of alleles of a peroxidase locus with salt tolerance during germination in the Caruaru population

Karta ��fver storfurstend��met Finland sammandragen, med st��d af de tillf��rlitligaste kartor uti general landtm��teri kontoret samt s��rskildte ben��get meddelade upplysningar, upp�� K. E. Holms f��rlag, af A. W. Eklund /

1 kartta :, v��r. ;, lehti 88,7 x 58 cm

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Mittakaava 1:105000

Fast and slow voltage modulation of apical Cl- permeability in toad skin at high [K+]

The influence of voltage on the conductance of toad skin was studied to identify the time course of the activation/deactivation dynamics of voltage-dependent Cl- channels located in the apical membrane of mitochondrion-rich cells in this tissue. Positive apical voltage induced an important conductance inhibition which took a few seconds to fully develop and was instantaneously released by pulse inversion to negative voltage, indicating a short-duration memory of the inhibiting factors. Sinusoidal stimulation at 23.4 mM [Cl-] showed hysteresis in the current versus voltage curves, even at very low frequency, suggesting that the rate of voltage application was also relevant for the inhibition/releasing effect to develop. We conclude that the voltage modulation of apical Cl- permeability is essentially a fast process and the apparent slow components of activation/deactivation obtained in the whole skin are a consequence of a gradual voltage build-up across the apical membrane due to voltage sharing between apical and basolateral membranes

Outward potassium current oscillations in macrophage polykaryons: extracellular calcium entry and calcium-induced calcium release

Outward current oscillations associated with transient membrane hyperpolarizations were induced in murine macrophage polykaryons by membrane depolarization in the absence of external Na+. Oscillations corresponded to a cyclic activation of Ca2+-dependent K+ currents (IKCa) probably correlated with variations in intracellular Ca2+ concentration. Addition of external Na+ (8 mM) immediately abolished the outward current oscillations, suggesting that the absence of the cation is necessary not only for their induction but also for their maintenance. Oscillations were completely blocked by nisoldipine. Ruthenium red and ryanodine reduced the number of outward current cycles in each episode, whereas quercetin prolonged the hyperpolarization 2- to 15-fold. Neither low molecular weight heparin nor the absence of a Na+ gradient across the membrane had any influence on oscillations. The evidence suggests that Ca2+ entry through a pathway sensitive to Ca2+ channel blockers is elicited by membrane depolarization in Na+-free medium and is essential to initiate oscillations, which are also dependent on the cyclic release of Ca2+ from intracellular Ca2+-sensitive stores; Ca2+ ATPase acts by reducing intracellular Ca2+, thus allowing slow deactivation of IKCa. Evidence is presented that neither a Na+/Ca2+ antiporter nor Ca2+ release from IP3-sensitive Ca2+ stores participate directly in the mechanism of oscillation

Fo��rso��k til en magnetisk inclinations charta

Irtokartta

Development of the insulin secretion mechanism in fetal and neonatal rat pancreatic B-cells: response to glucose, K+, theophylline, and carbamylcholine

We studied the development of the insulin secretion mechanism in the pancreas of fetal (19- and 21-day-old), neonatal (3-day-old), and adult (90-day-old) rats in response to stimulation with 8.3 or 16.7 mM glucose, 30 mM K+, 5 mM theophylline (Theo) and 200 ��M carbamylcholine (Cch). No effect of glucose or high K+ was observed on the pancreas from 19-day-old fetuses, whereas Theo and Cch significantly increased insulin secretion at this age (82 and 127% above basal levels, respectively). High K+ also failed to alter the insulin secretion in the pancreas from 21-day-old fetuses, whereas 8.3 mM and 16.7 mM glucose significantly stimulated insulin release by 41 and 54% above basal levels, respectively. Similar results were obtained with Theo and Cch. A more marked effect of glucose on insulin secretion was observed in the pancreas of 3-day-old rats, reaching 84 and 179% above basal levels with 8.3 mM and 16.7 mM glucose, respectively. At this age, both Theo and Cch increased insulin secretion to close to two-times basal levels. In islets from adult rats, 8.3 mM and 16.7 mM glucose, Theo, and Cch increased the insulin release by 104, 193, 318 and 396% above basal levels, respectively. These data indicate that pancreatic B-cells from 19-day-old fetuses were already sensitive to stimuli that use either cAMP or IP3 and DAG as second messengers, but insensitive to stimuli such as glucose and high K+ that induce membrane depolarization. The greater effect of glucose on insulin secretion during the neonatal period indicates that this period is crucial for the maturation of the glucose-sensing mechanism in B-cells.

E��kspedici��i k" ust'a��m" Enisea�� 1875 i 1876 godov": so stat'eu�� ad"u��nkt" professora zoologi��i Upsal'skago universiteta G. Te��la�� o plavani��i ego po Eniseu�� v" 1876 godu i dvu'ma�� kartami plavani��a��

Perevod s" s��vedskago.

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Kartta kuuluu A. E. Nordenskio��ldin kokoelmaan

K-liitoksen ep��keskeisen tuennan aiheuttaman sekund����risen momentin m����ritys

Ty��ss�� on tutkittu laboratoriokokeen ja elementtimenetelm��n avulla eri geometrioiden vaikutusta sekund����riseen momentin syntymiseen K-liitoksella. Kokeen liitos on tehty S700-lujuusluokan Ruukin Optim 700 plus MH nelikulmaisista rakenneputkista (RHS). Elementtimalleissa on k��ytetty geometrista ja materiaalista ep��lineaarisuutta ennustamaan liitoksen muodonmuutoskyky�� ja laskennallista kest��vyytt��. Liitoksen elementtimalleissa muutettavia geometrioita ovat: vapaav��li, uumasauvan ja paarteen v��linen kulma, paarteen sein��m��n paksuus, liitoksen eksentrisyys ja uumasauvan ja paarteen leveyden suhde. Laboratoriokokeen liitoksen vetouumasauvassa vaikuttava sekund����risen momentin aiheuttama j��nnitys on noin 25 % vetouumasauvan my��t��rajasta. Suurin sekund����rinen momentti syntyy, kun vapaav��li�� pienennet����n ja uumasauvaa kavennetaan paarteeseen n��hden. Eurocode 3:n mitoitusohjeita voidaan elementtimallien perusteella soveltaa tietyille geometrioille turvallisesti.