Cyclic GMP-dependent protein kinase activation in canine tracheal smooth muscle by methacholine and sodium nitroprusside

Methacholine (3 μM) and sodium nitroprusside (300 μM) increased cGMP-dependent protein kinase activity ratios (activity without cGMP divided by activity with 2 μM cGMP) in canine tracheal smooth muscle from a control value of 0.47 to 0.55 and 0.71, respectively. This correlates with 3-fold and 6-fold increases in cGMP concentrations in response to methacholine and sodium nitroprusside, respectively. Addition of charcoal to the homogenizing buffer prior to homogenization had no significant effect on the cGMP-dependent protein kinase response to either agent, suggesting that activation of the enzyme was not occurring as a result of cGMP release during homogenization. In order to limit cGMP dissociation from cGMP-dependent protein kinase during the assay procedure, it was necessary to perform assays at a reduced temperature (0°C) and with an abbreviated incubation time (2.5 min). When assayed at 30°C, activated cGMP-dependent protein kinase rapidly lost activity. This inactivation occurred whether the enzyme had been activated exogenously, by exposing a supernatant fraction of canine trachealis to 0.1 μM cGMP, or endogenously, by treating intact canine trachealis with methacholine or sodium nitroprusside. By assaying instead at 0°C, the inactivation of cGMP-dependent protein kinase was minimized. Therefore, the activity ratio obtained by this new modified assay provided an estimate of the endogenous activation state of cGMP-dependent protein kinase. The data indicate that cGMP responses in canine trachealis to both methacholine and sodium nitroprusside are functionally linked to activation of cGMP-dependent protein kinase and are consistent with the hypothesis that cGMP, via cGMP-dependent protein kinase activation, regulates smooth muscle contractility.     

Swimming behavior of X and Y human sperm

Abstract. A laminar-flow fractionation method, developed primarily for removing dead sperm from human semen, was successfully modified to enrich X and Y sperm to 80% purity, and to characterize each enriched fraction for individual swimming behavior. Y-sperm fractions were rapidly detected by fluorescent cytogenetic staining. Subsequently, the degree of enrichment was quantitated with DNA extracted from each sperm fraction probed with a human male-specific recombinant DNA clone. In stationary fluid, X and Y sperm swam in circles with the same average speed. However, in a flowstream, X sperm shifted to a nearly straight path of movement in a significantly decreased angular velocity. This shift was four times more pronounced in X sperm than in Y sperm, especially after the initial transition from stationary fluid to flow. The velocity gradient across the flow axis was essential for separating X and Y sperm; uniform flow velocity did not separate them effectively.     

Functional interaction of constant and variable domains of human immunodeficiency virus type 1 gp120.

A previously reported amino acid substitution within the second conserved domain of the human immunodeficiency virus type 1 (HIV-1) gp120 envelope results in the production of noninfectious particles. Molecular characterization of spontaneous revertant viruses, which arose during long-term cocultures of this env mutant, revealed that an amino acid change within another region of gp120 could functionally compensate for the mutation and restore infectivity. In the current study, we have introduced a conservative amino acid substitution at this second-site revertant codon and observed a marked reduction in HIV-1 infectivity. During the passage of this defective virus in cocultures, yet another revertant appeared which contained an amino acid change within a variable region of gp120 which restored infectivity to near wild-type levels. These results, in combination with other point mutations that have been introduced into the HIV-1 envelope, suggest that at least three discrete regions of gp120 may interact during the establishment of a productive viral infection. This critical step occurs subsequent to the adsorption of virions to the cell surface and either prior to or concomitant with the fusion of viral and cellular membranes.     

Norepinephrine content of the rat kidney during development: Alterations induced by perinatal methadone

The concentration and the total content of norepinephrine (NE) in the kidney were measured in Sprague-Dawley rats from 3 to 120 days after birth. Renal NE concentration was relatively low until the end of the second week, when it rose abruptly to adult levels; total NE content per kidney increased steadily throughout development. The effects of perinatal methadone treatment on renal NE development were examined by administering the drug either directly to the pups from 1 to 19 days after birth, or to the mother from 10 days of gestation to 20 days after birth. Both treatments resulted in significant deficits of body weight and kidney weight. Maternal methadone caused a significant deficit in renal NE which was most pronounced at two weeks of postnatal age; direct methadone had less effect on renal NE. These results suggest that renal sympathetic neurotransmission may become mature two weeks after birth and indicate further that maternal methadone interfares with this maturation.     

Parallel trends in the species diversity of west indian birds and bats

Summary In this paper I compare several biogeographic patterns of West Indian resident land birds and bats, including species-area and trophic diversity-area relationships, the number of islands inhabited per species and levels of endemism, trophic structure as compared with tropical mainland areas, and the degree of faunal simlarity between islands of similar sizes but different locations. In most respects, the bat and bird patterns are strikingly similar. Groups of birds that are conspicuously missing from the Antilles because of the absence of appropriate resources also have missing chiropteran counterparts. Plant-visiting bats and birds are better-represented in terms of relative number of species and, in birds, in biomass, on the Lesser Antilles than on the mainland (e.g. Panama). Small Antillean islands tend to share more species of birds and bats than do larger islands. Stochastic (sensu Simberloff 1978), deterministic, and interactive (e.g. competitive and trophic interactions) factors appear to underly these biogeographic trends. No evidence exists to suggest that Caribbean bats and birds have negatively affected each other's diversity.     

A new electroreceptive teleost:Xenomystus nigri (Osteoglossiformes: Notopteridae)

Summary The African knife fish,Xenomystus nigri, is found to be sensitive to weak electric fields by the method of averaged evoked potentials from the brain. Slow waves and spikes were recorded in or near the lateral line area of the medulla and the torus semicircularis of the mesencephalon in response to long pulses (best > 50 ms) and low frequency sine waves (best ca. 10 Hz) of voltage gradients down to < 10 V/cm. Evoked waves in the lateral line area are a sequence of negative and positive deflections beginning with a first peak at ca. 24 ms; in the torus semicircularis the first peak is at ca. 37 ms. Spikes are most likely in the torus between 50 and 80 ms after ON. At each recording locus there is a best axis of the homogeneous electric field and a better polarity. Effects of stimulus intensity, duration and repetition are described. The physiological properties are similar to those of ampullary receptor systems in mormyriforms, gymnotiforms and siluriforms.Confirming Braford (1982),Xenomystus has a large medullary nucleus resembling the nucleus otherwise peculiar to mormyriforms, gymnotiforms and siluriforms and now called the electrosensory lateral line lobe (ELLL; formerly the posterior lateral line lobe). We describe the projections of anterior and posterior lateral line nerves by HRP applied to the proximal stump of a cut nerve. A descending central ramus of the anterior lateral line nerve and a lateral component of the ascending ramus of the posterior lateral line nerve end in part in the ELLL.Electroreception, including the system of discrete central structures mediating it, is for the first time found to be less than an ordinal or even a family character, but apparently a characteristic of the subfamily Xenomystinae. Species of the other subfamily, Notopterinae as well as of the other families of osteoglossiforms (Osteoglossidae, Hiodontidae and Pantodontidae), lack the ELLL.Notopterus andPantodon are found to lack the evoked potential.The positive finding of evoked activity to feeble electric field is found to be the most practical method for searching widely among fishes for the presence of the electrosense modality and its central pathways. The anatomical criterion of an ELLL can now be taken to be a good criterion for the presence of this sensory system. The absence of evoked response correlates well with the absence of an ELLL.Abbreviations ELLL electrosensory lateral line lobe - HRP horseradish peroxidase - TS torus semicircularis     

Ethanol-induced inhibitions of testicular steroidogenesis in the male rat: Mechanisms of actions

Ethanol markedly inhibits the biosynthesis of testosterone in the male of several species. Since several $\text{in vitro}$ studies have suggested that ethanol $\text{per se}$ is not a gonadal toxin and that it must be metabolized to exert its effects, we examined this possibility under $\text{in vivo}$ conditions in the present studies. We found that the administration of the alcohol dehydrogenase inhibitor, pyrazole, to adult male rats significantly elevated blood ethanol levels. However, rather than resulting in a potentiation of the effects of ethanol on testicular steroidogenesis, pyrazole-induced elevations in blood ethanol concentrations produced a significant attenuation of ethanol's effects. In view of these observations, it is difficult to maintain that ethanol itself is responsible for inhibiting the production of testosterone. On the contrary, our results may provide the first $\text{in vivo}$ support for the hypothesis that ethanol must be metabolized to exert its effects on testicular steroidogenesis.     

WINTER ROOSTING AND FEEDING BEHAVIOUR OF PIED WAGTAILS MOTACZLLA ALBA NEAR OXFORD, ENGLAND

This study presents data on the roosting and feeding behaviour of Pied Wagtails around Oxford, England. During the winter of 1977–78, from two to 1200 wagtails roosted in a Phragmites reed-bed. Use of this roost was greatest during mild, windless weather and the birds apparently used alternate roosts during harsh weather. Movement between roosts sometimes occurred between sunset and sunrise. Morning ‘departure group’ size, number leaving per unit time and diversity of departure directions increased with roost size. Wagtails quickly left the vicinity in the morning. In the afternoon, they joined one or more pre-roost gatherings before entering the roost for the night. Behaviour upon arrival at the roost was variable: birds might enter the reeds quickly or circle in large groups before landing. Aerial revolutions and generally ‘restless’ behaviour often accompanied increases in roost size. Wagtail feeding rates varied significantly between and within habitats. Number of wagtails feeding on the flooded Port Meadow, located 2–3 km south of the main roost, varied from about five to over 60 on different days; these numbers were not correlated with feeding rates. In contrast, the number of birds feeding at a sewage farm was nearly constant all winter. Some wagtails show high fidelity to feeding areas but others do not. Five short-term food supplementation experiments indicated that wagtails knowledgeable about a dense food source are not followed in the morning by naive birds. Results of this study are discussed in relation to the predation, physiology and information centre hypotheses that have been suggested to explain communal roosting in birds. I conclude that the communal roosting system of Pied Wagtails has physiological and anti-predator functions. Wagtails appear to choose certain roosts because of the protection that they provide from adverse climate and predation.     

Carex hermannii (Cyperaceae), a new species from Mexico,with comments on related species at high altitudes in middle America

Carex hermannii, a new species known only from a few populations on large volcanic mountains on the Puebla-México state border, central Mexico, is described, illustrated and compared with its nearest relative,C. cuchumatanensis of Guatemala. Both these species have been confused until now with the more distantly relatedC. endlichii. Morphological comparisons ofC. hermannii, C. cuchumatanensis andC. endlichii confirm the distinctiveness of these species.     

Errata

1. (1) The significance of the specific (ouabain-sensitive) ⁸⁶Rb⁺ or ⁴²K⁺ uptake by cardiac muscle preparations which are not ‘sodium-loaded’ was studied.

2. (2) In left atrial preparations of guinea-pig heart, resting ⁸⁶Rb⁺ uptake was relatively low. It was markedly increased by electrical stimulation. This stimulated uptake was further enhanced by isoproterenol and inhibited by verapamil.

3. (3) In rat atria, the resting ⁸⁶Rb⁺ uptake was somewhat higher than in guinea-pig atria, and the increase in uptake caused by electrical stimulation was smaller. In guinea-pig right ventricular papillary muscle, the resting uptake was highest among those tissues studied, and the response to electrical stimulation was smallest. In the latter tissue, verapamil produced only a minimal inhibition of the specific ⁸⁶Rb⁺ uptake.

4. (4) The effect of the frequency of electrical stimulation on ⁸⁶Rb⁺ uptake paralleled its influence on the force of contraction, suggesting the involvement of intracellular sodium in both events.

5. (5) In both left atrial and right papillary muscle preparations of guinea-pig heart, specific ⁴²K⁺ uptake observed with 5.8 mM K⁺ was relatively high, and was increased only slightly by electrical stimulation. This electrical stimulation, however, increased ouabain-induced inhibition of ⁴²K⁺ uptake, suggesting that the stimulation increases the amount of Na⁺ available to the sodium pump.

6. (6) When the K⁺ concentration was 1 mM, the resting ⁴²K⁺ uptake was low, and could be enhanced by electrical stimulation.