Antigenic Relationship Between Plasmodium falciparum and Babesia bovis: Reactivity with Antibodies to Culture-Derived Soluble Exoantigens1

Antigenic similarities between Plasmodium and Babesia parasites of the phylum Apicomplexa have been previously demonstrated primarily by the serological cross reactivity observed in the indirect fluorescent antibody (IFA) test. We have now studied the antigenic relationship between the human malaria parasite, Plasmodium falciparum, and the hemoparasitic agent of cattle, Babesia bovis, using rabbit monospecific antibodies produced against individual culture-derived P. falciparum polypeptides and bovine polyspecific antibodies to B. bovis exoantigens. These respective antibodies were found to be distinctly cross reactive in the IFA test using infected erythrocytes (squirrel monkey—P. falciparum; bovine—B. bovis) as antigen substrates. Immunofluorescence was shown to be highly specific for parasite surfaces. Additionally, the degree of reactivity with soluble exoantigens contained in Plasmodium and Babesia culture supernatants was monitored by a two-site enzyme immunoassay employing the cross-reactive antibodies. Further evidence for antigenic cross reactivity between P. falciparum and B. bovis parasites was shown with the in vitro inhibition assay. Antibodies to P. falciparum and B. bovis were found to be highly inhibitory for the in vitro growth of P. falciparum in human erythrocytes.     

Plasma levels of arginine vasotocin,prolactin, aldosterone and corticosterone during prolonged dehydration in the domestic flowl: effect of dietary NaCl

Three groups of White Plymouth Rock laying hens were adapted to three levels of dietary NaCl: low-NaCl food with tap water (LOW), high-NaCl food (1% NaCl w/w added) with tap water (HT), and high-NaCl food with 0.5% NaCl for drinking (HS). The birds were subjected to water deprivation (dehydration) for 18 days. Blood sampling was done at 2-4 day intervals. Plasma concentrations of arginine vasotocin (AVT), prolactin (PRL), aldosterone (ALDO) and corticosterone (CS) were determined by radioimmunoassay. Plasma osmolality, sodium, chloride, and potassium were also determined. In the normally hydrated hens fully adapted to the diets, there was a stepwise increase from LOW to HS in plasma osmolality (305, 315, 332 mOsm, for LOW, HT and HS, respectively), [Na+] (144, 153, 161 mM) and [Cl-] (109, 119, 127 mM) as well as in [AVT] (6, 14, 18 pg/ml) and [PRL] (16, 24, 34 ng/ml). Regressing [AVT] on osmolality gave a slope of 0.30 pg . ml-1/mOsm and a threshold of 273 mOsm. The slope of [PRL] on osmolality was 0.73 ng . ml-1/mOsm. The correlation coefficient of [AVT] and [PRL] was 0.67. LOW had high [ALDO] (165 pg/ml) which was suppressed to low levels in HT and HS (5-8 pg/ml), while [CS] was the same in all groups (0.9-1.1 ng/ml). Plasma [K+] was decreased in the high-NaCl groups (5.8 mM in LOW, 4.4 and 4.7 mM in HT and HS). Dehydration resulted within 2 days generally in a sharp (5-15%) increase in osmolality, [Na+] and [Cl-], which thereafter increased more slowly during the remaining 16 days in all groups, with the slowest increase in LOW. The levels of osmolality [Na+] and [Cl-] were 5% lower in LOW than in HT and HS, which showed the same levels during the dehydration period. Plasma [AVT] and [PRL] increased 2-4 fold within 2 days of dehydration; [AVT] reached a plateau at 29 pg/ml in all groups, but [PRL] continued to rise in all groups, fastest in LOW, reaching similar levels in all groups after 14-18 days of dehydration, about 85 ng/ml. The correlation coefficient of [AVT] and [PRL] was decreased by half (to 0.32) during dehydration. Plasma [ALDO] increased in all groups with dehydration, 1.7 fold in LOW and 3-6 fold in HT and HS, but the levels reached in HT and HS were only 15-30% of that seen in LOW.(ABSTRACT TRUNCATED AT 400 WORDS)     

The Gomphaeschninae (Odonata: Aeshnidae): new fossil genus, reconstructed phylogeny, and geographical history

ABSTRACT. Three new species of fossil Anisoptera (dragonflies) are reported from Tiffanian (Late Palaeocene) sediments of the Paskapoo Formation, near Red Deer, Alberta, Canada. The three species are all assigned to the new genus Alloaeschna , which is classified in the subfamily Gomphaeschninae.
Phylogenetic analysis of gomphaeschnine wing venation suggests that the subfamily is paraphyletic, with derived gomphaeschnines such as Boyeria and Linaeschna more closely related to the Brachytroninae and Aeshninae than are other gomphaeschnines. One of the most primitive gomphaeschnines, and the oldest fossil form, is the Jurassic Morbaeschna. Parallelism, convergence and reversal in the evolution of features of the wing venation is common.
The new genus Alloaeschna is at about the same evolutionary grade as the old-world genus Oligoaeschna and the new-world genus Gomphaeschna , and is one of the more primitive known members of the Gomphaeschninae. The new species are the first recorded Palaeocene gomphaeschnines and the oldest known gomphaeschnines from the Americas.
Several extant genera have fossil representatives on continents different from those on which they now survive, suggesting repeated crossing of land bridges and/or widespread ancestral species prior to the separation of the continents, and subsequent extinction leading to present relict distributions.     

Histocompatibility Gene Organization and Mixed Lymphocyte Reaction

TRANSFORMATION of allogenic lymphocytes in mixed cultures depends chiefly on an incompatibility between the lymphocyte donors at the major histocompatibility locus in man (HL-A), mouse (H-2) and rat (H-l)¹. Although the mouse H-2 locus can be divided into several regions each of which controls one or more antigenic specificities² and two or more subloci control HL-A antigens in man³, it is not known whether all parts of the major histocompatibility locus are equally important in eliciting transformation in mixed lymphocyte cultures. We now show that capacity to elicit lymphocyte transformation is different for different parts of the mouse H-2 locus.     

Interactions between Marek's Disease Herpesvirus and Avian Leucosis Virus in Tissue Culture

A GROUP B herpesvirus is important in the aetiology of Marek's disease, a highly contagious lymphoproliferative disease of chickens^1,2. Chicks inoculated with enveloped Marek's disease herpesvirus (MDHV), extracted from feather follicle epithelium of chickens with the disease, developed tumour-like aggregates of lymphoid cells in the viscera and frequently in the peripheral nerves^3,4. Cultures of chicken embryo fibroblast (CEF) cells infected with MDHV develop discrete foci of altered cells⁵. Our data show that MDHV infection of cultures of CEF cells, previously infected with an avian leucosis virus (RAV-2), results in both a reduction in the number of MDHV foci and an increase in the complement fixing avian leucosis antigen (COFAL)⁶ titre.     

Convergence of signals of various sensory modalities on the neurons of the sensorimotor zone of the rabbit cerebral cortex

The responses of the neurons to electrocutaneous stimulation, light flashes, and clicks in the cortical region of the motor representation of the rabbit forelimb were investigated by means of intra- and quasiintracellular recordings. In unanesthetized animals, in only eight out of 65 neurons did postsynaptic potentials (PSP) with a short (10–30 msec) latent period arise in response to light and sound. In 15 neurons, long latency (50–150 msec) responses to one or both of these stimuli were recorded. In most of the cells, short latency stable responses to stimulation of the contralateral forelimb and unstable long latency responses to light and/or sound, frequently of the nature of an increase in the background "synaptic noise," were observed. Under deep chloralose narcosis, the type of convergence was sharply changed: in most of the neurons, short latency responses to all the stimuli used appeared. However, the picture of convergence differed from that described earlier [5,6] for the motor cortex of the cat under chloralose narcosis. The responses to various stimuli were less similar to one another; the somesthetic modality substantially "predominated" (judging by the stability and nature of the interaction of the response).Brain Institute, Academy of Medical Sciences of the USSR. Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 5, pp. 474–483, September–October, 1971.     

Postinhibitory unit response of crustacean stretch receptors after direct and recurrent inhibition

The postinhibitory response of a slowly adapting neuron was investigated in experiments on an isolated preparation of crustacean stretch receptor and abdominal nerve chain. The structural features of this preparation are such that this response can be regarded as the response of the postsynaptic membrane to synaptic inhibition and not the action of synaptic excitation. IPSPs arise in the slowly adapting neuron in response to stimulation of the abdominal nerve chain (direct inhibition) or to excitation of the neuron itself (recurrent inhibition). The postinhibitory response consists of the development of action potentials or an increase in their amplitude and frequency. The magnitude of the response is determined by the duration of the inhibition and the state of the neuron membrane. The postinhibitory response was strongest when IPSPs were superposed on cathodal depression. IPSPs and an intracellular hyperpolarizing current evoke similar postinhibitory responses. Repetitive excitation of an inhibitory neuron may result in the appearance of a regular spike discharge from a previously inactive neuron through the mechanism of the postinhibitory response. Activation of a chain of recurrent inhibition increases the duration of the postinhibitory response evoked by direct inhibition or by a hyperpolarizing current. The existence of a chain of recurrent inhibition prevents the cessation of firing by a neuron during increasing cathodal depression. A mechanism of postinhibitory rebound lies at the basis of this phenomenon.     

Analysis of theta-rhythms recorded in an isolated strip of rabbit sensomotor cortex

To test the possibility that the theta-rhythm may spread passively from the hippocampus into the neocortex in rabbits and to analyze the properties of these rhythms recorded from the surface of the neocortex, an investigation was made of activity recorded simultaneously from the hippocampus and various points of the neocortex, including from a strip of the sensomotor cortex isolated completely with respect to its nervous connections. The use of special correlation methods showed that an appreciable contribution to the potentials recorded from the isolated strip can be made by the passive conduction of hippocampal activity (provided that it generates a regular high-amplitude theta-rhythm). At the same time, potentials in a theta-rhythm may be generated in the isolated strip itself. The theta-rhythm recorded in the intact rabbit cortex may thus be of combined genesis: generated in the neocortex itself and spreading passively from the hippocampus through the brain tissues as through a volume conductor.