Evidence for a Selective Localization of Voltage-Sensitive Ca2+ Channels in Nerve Cell Bodies of Corpus Striatum

Specific binding sites for [3H]nitrendipine, an organic Ca2+ channel antagonist, were abolished in crude synaptosomal membranes of kainic acid-lesioned caudate nuclei. In contrast, specific lesions of dopaminergic or serotonergic axon terminals in caudate nuclei failed to alter the density or the affinity of [3H]nitrendipine binding sites. In addition, the basal and veratridine-stimulated 45Ca2+ accumulations were greatly impaired in slices prepared from kainic acid-lesioned caudate nuclei. The veratridine-elicited accumulation of 45Ca2+ in control slices was attenuated by addition of tetrodotoxin in the incubation medium. The present data provide evidence that most of the [3H]nitrendipine binding sites and the voltage-dependent Ca2+ channels are located in intrinsic neurons or interneurons in caudate nucleus. In contrast, destruction of dopaminergic or serotonergic nerve terminals emanating from other brain areas and innervating the caudate nucleus failed to change the apparent Bmax value for [3H]nitrendipine binding.     

Lack of evidence of hepatitis D (delta) infection in Newfoundland and Labrador.

Epidemiologic knowledge of hepatitis D virus (HDV) infection is limited. A seroepidemiologic study was undertaken to determine the prevalence of the infection in Newfoundland and Labrador. Between October 1983 and October 1985 over 200 people were recognized through routine serodiagnosis and screening as having hepatitis B seromarkers. A total of 223 serum samples from 186 of these people were tested for anti-HDV. The subjects were mainly asymptomatic carriers of hepatitis B surface antigen or patients with acute or chronic hepatitis B from the native Indian and Inuit and the non-native populations. None of the serum samples were positive for anti-HDV. The absence of anti-HDV in a substantial number of people in the province who are infected with hepatitis B virus is strong evidence that HDV infection is not prevalent in the local population, including native people.     

Biphasic radiosensitization of human lymphocytes by diethyldithiocarbamate: possible involvement of superoxide dismutase

A biphasic radiosensitization of human lymphocytes by diethyldithiocarbamate (DDC), a metal chelator, was observed. The first phase occurred at 10(-5) M and the second at 10(-3) MDDC. The biphasic radiosensitization coincided with the previously reported biphasic toxicity of DDC. Inhibition of superoxide dismutase (SOD) occurred only in the second phase, suggesting that it may be a contributing cause of this phase. The mechanism of the first radiosensitization phase is not known. The radiation survival curves indicated the presence of at least two lymphocyte populations differing in their radiosensitivity and representing 40 per cent and 60 per cent of the cells. Both cell populations were biphasically radiosensitized by DDC.     

Glutamate receptor binding to cat central nervous system membranes

L-[3H]Glutamate exhibited specific binding to fresh membranes of cat CNS under physiological conditions of pH and temperature. This binding occurred in the absence of sodium ions. Kinetic analysis of the data for cerebellum suggested the presence of two distinct binding sites: a high-affinity process (Kd = 0.33 microM) with a capacity of 15 pmol/mg protein and a low-affinity process (Kd = 1.8 microM) which had a capacity of 65 pmol/mg protein. Several structural analogues of glutamic acid were able to appreciably inhibit the binding of [3H]glutamate. The distribution of glutamate binding between 12 regions of the CNS was measured. The amygdaloid complex exhibited the highest binding followed by hippocampus > hypothalamus identical to visual cortex identical to thalamus identical to caudate nucleus > olfactory bulb identical to tectum identical to cerebellum > dorsal pons identical to medulla > cervical spinal cord. These findings are consistent with the binding of [3H]glutamate being to its receptor.     

The Holocene Prehistory of a coastal wetland system: Discovery Bay,Southeastern Australia

Recent theories of socio-economic change in hunter-gatherer societies have referred to associated changes in intensity and mode of resource exploitation. These ideas are examined in the light of pollen and charcoal analyses of an Australian coastal wetland system which allow, at the local scale, (1) documentation of resource availability, (2) identification of resource use, particularly where fire technology is involved, and (3) examination of the effect of environmental change on the archeological record. Evidence of plant food management through fire around 6800 BP suggests a longer history of deliberate swamp exploitation than indicated by the archeological record, and lends support to models which propose long-term gradual change in zones of high productivity.     

Enhancement of gamma-glutamyl transpeptidase expression in bone marrow cells by colony stimulating factors

Studies on blood serum from mammary carcinoma (MC) hosts, which promoted gamma-glutamyl transpeptidase (GGT) expression by normal rat bone marrow cells in liquid culture, were extended to various granulocyte-macrophage colony stimulating factors (CSFs). GGT concentration per cell was found to increase (without change in total cell number) by incubation for 48 h with purified CSF-2 gamma and CSF-1 (but not interleukin-3), with human giant cell elaborated GM-CSF and L-cell conditioned medium, as well as with the 3 MC preparations (host serum, MC extract and MC conditioned medium). GGT-inducing ability (per milligram protein) ranked the 7 preparations in the same order as did their proliferative effect (number of colonies per milligram protein) in the standard mouse bone marrow agar culture system. The quantitative correlation between these two kinds of activities (linear for their logarithmic values) was highly significant, r = 0.976, p less than 0.001. The alkaline phosphatase concentration of bone marrow cells in liquid culture was also increased in the presence of the same 7 preparations, and this again was proportional (r = 0.985, p less than 0.001) to their colony stimulating potential.     

An experimental test for body size‐dependent effects of male harassment and an elevated copulation rate on female lifetime fecundity and offspring performance

Many studies investigate the benefits of polyandry, but repeated interactions with males can lower female reproductive success. Interacting with males might even decrease offspring performance if it reduces a female's ability to transfer maternal resources. Male presence can be detrimental for females in two ways: by forcing females to mate at a higher rate and through costs associated with resisting male mating attempts. Teasing apart the relative costs of elevated mating rates from those of greater male harassment is critical to understand the evolution of mating strategies. Furthermore, it is important to test whether a male's phenotype, notably body size, has differential effects on female reproductive success versus the performance of offspring, and whether this is due to male body size affecting the costs of harassment or the actual mating rate. In the eastern mosquitofish Gambusia holbrooki, males vary greatly in body size and continually attempt to inseminate females. We experimentally manipulated male presence (i.e., harassment), male body size and whether males could copulate. Exposure to males had strong detrimental effects on female reproductive output, growth and immune response, independent of male size or whether males could copulate. In contrast, there was a little evidence of a cross‐generational effect of male harassment or mating rate on offspring performance. Our results suggest that females housed with males pay direct costs due to reduced condition and offspring production and that these costs are not a consequence of increased mating rates. Furthermore, exposure to males does not affect offspring reproductive traits.