Foraging strategies ofDrosophila melanogaster: A chromosomal analysis

Two larval foraging strategies inDrosophila melanogaster were identified, rover and sitter. Rovers traverse a large area while feeding whereas sitters cover a small area. The difference between rovers and sitters was analyzed genetically by chromosomal substitutions between isogenic stocks. Differences in larval locomotor behavior (crawling behavior) can be attributed to the second chromosome, the rover strategy being dominant over the sitter strategy. Differences in feeding rate (shoveling behavior) are affected additively by both the second and third chromosomes. Natural populations ofDrosophila larvae were sampled three times over a 2-month period; rovers and sitters were at constant frequencies in these populations. The two foraging strategies are discussed in the light of resource utilization in environments where food is distributed continuously or discontinuously.     

Lability in the responses of cells in the auditory cortex of squirrel monkeys to species-specific vocalizations

Summary The activity of 28 cells located mainly in the secondary auditory cortex (A II) of awake squirrel-monkeys, was extracellularly recorded for periods of up to 6 h. Seven different species-specific vocalizations, which were repeatedly presented to the monkey, were used as auditory stimuli. Twenty-six cells responded, at least once, to one or more vocalizations; 22 cells revealed some change in their response (pattern or strength) to at least one vocalization (change in response). Twenty-one cells exhibited a change in the number and/or type of vocalization to which they responded during the recording period (change in selectivity). At some time during the recording period all the responding cells exhibited a change in response and/or a change in selectivity (change in responsiveness). A change in response of a cell to a vocalization did not necessarily exclude a change in selectivity, associated with the same vocalization, later in time and vice-versa. A change in responsiveness to one vocalization was not necessarily correlated with changes in responsiveness to other vocalizations.     

On the existence of a lyotropic and osmotic type of collagen swelling produced by representative electrolytes and anelectrolytes

Summary The influence of NaI, NaCl, urea, glucose and sucrose on venous tissue volume were studied with regard to osmotic (electrostatic and dehydrating) and lyotropic effects. NaI leads to the highest volume increase and to the extreme irreversibility of this change. The tested anelectrolytes cause a decrease of tissue volume over the whole range of concentration with the exception that, beyond 1.0 osM, urea causes an increase. The large reversibility of this increase is pointed out. A strict discrimination between osmotic and lyotropic volume change is questioned.     

Causal dimensions of college students' perceptions of physical symptoms

According to attribution theory, controllability, locus, and stability are important dimensions underlying causal explanations. The extent to which these theoretical dimensions underlie lay explanations for physical symptoms is unclear. Accordingly, in this study, attributes relevant to the lay public were empirically derived using a multidimensional scaling (MDS) procedure. Undergraduates (N=194) provided similarity judgments for 18 potential causes of physical discomfort. The MDS analysis yielded a three-dimensional solution. The first dimension captured the distinction between physical and nonphysical causes. The second dimension distinguished either variable versus stable causes or those that are controllable versus uncontrollable by health care professionals. The third dimension differentiated causes under low versus high personal control. These findings empirically confirm the theoretically proposed dimensions of personal control and stability and suggest the utility of considering the physical/nonphysical and controllability by health care professional distinctions in future work on attributions in the health domain.     

Acetylcholine metabolism in the brain of rats treated with vanadyl sulfate and certain phenylacetic acid derivatives

Summary The present work describes the effect produced by phenylacetic acid, phenylethylacetic and diphenylacetic acids (sodium salts) separated and together with vanadyl sulfate on some indices, of acetylcholine metabolism in the rat's brain. Total cholinesterase activity and the free and bound (conditionally) acetylcholine levels served as indices. As shown experimentally the use of phenylacetic acid derivatives is accompanied by reduction of the bound acetylcholine, content, whereas that of free acetylcholine and the total tissue cholinesterase activity remain unchanged. Vanadyl sulfate provokes a significant reduction of the total tissue cholinesterasic activity, but does not change the content of free and bound acetylcholine therein. In conjoint action of the above-mentioned substances, the effects of phenylacetic acid erivatives are supplemented by the anticholinesterase effect of vanadyl sulfate.(Presented by Active Member AMN SSSR S. V. Anichkov) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 57, No. 2, pp. 80–83, February, 1964     

Sodium chloride preference in hypertensive (H) and normotensive (N) rats

Summary Salt consumption was compared in two strains of rats, selected for their disparate proneness (strain H) or resistance (strain N) to Doca-salt hypertension.NaCl intake was similar in H and N rats prior to an following administration of Doca, while their respective blood pressures at the end of this experiment was 178±5 mm Hgvs. 134±3 mm Hg. Thus, disparate responses of the blood pressure to Doca in the two strains cannot be ascribed to differences in salt intake.In another study, salt preference was tested in H and N rats by two-bottle self-selecting technique. Before Doca, saline preference in H rats averaged 60.3±5.8% of total daily fluid consumption,vs 18±4.2% in N rats. Following Doca treatment for 3 weeks the respective values were 96±1.7%vs. 67±6.6%. Thus Doca treatment enhanced salt appetite in both strains, but salt preference remained significantly higher in the H rats.The increased susceptibility to hypertension and the enhanced salt appetite in the H rat, corroborates similar reports in the Okamoto SH rat. In the Brookhaven S rat, however, susceptibility to hypertension is associated with salt avoidance. The conflicting data do not support a unified concept of a genetically determined link between salt appetite and proneness to hypertension.This work was supported in part by a grant from the joint research fund of the Hebrew University-Hadassah Medical School, Jerusalem, and by a grant in aid from Merck Sharpe and Dohme, Research Laboratories.     

Firing characteristics of vestibular nuclei neurons in the alert monkey after bilateral vestibular neurectomy

Summary After destruction of the peripheral vestibular system which is not activated by moving large-field visual stimulation, not only labyrinthine-ocular reflexes but also optokinetic-ocular responses related to the velocity storage mechanism are abolished. In the normal monkey optokinetic-ocular responses are reflected in sustained activity changes of central vestibular neurons within the vestibular nuclei. To account for the loss of optokinetic responses after labyrinthectomy, inactivation of central vestibular neurons consequent on the loss of primary vestibular activity is assumed to be of major importance. To test this hypothesis we recorded the neural activity within the vestibular nuclear complex in two chronically prepared Rhesus monkeys during a period from one up to 9 and 12 months after both vestibular nerves had been cut. The discharge characteristics of 829 cells were studied in relation to eye fixation, and to a moving small and large (optokinetic) visual stimulus producing smooth pursuit (SP) eye movements and optokinetic nystagmus (OKN). Units were grouped into different subclasses.After chronic bilateral vestibular neurectomy (BVN) we have found: (1) a rich variety of spontaneously active cells within the vestibular nuclear complex, which — as far as comparison before and after BVN is possible — belong to all subclasses of neurons functionally defined in normal monkey; and (2) no sustained activity changes which are related to the activation of the velocity storage mechanism; this is especially true for pure-vestibular, vestibular-pause and tonic-vestibular-pause cells in normal monkey which show a pure, pause and tonic-pause firing pattern after BVN. Neurons which are modulated by eye position are, however, modulated with the velocity of slow eye movements with comparable sensitivity during SP and OKN. Retinal slip is extremely rarely encoded. The results of the present study do not directly answer the question why the velocity storage mechanism is abolished after BVN but they suggest that only a small number of central vestibular cells may be inactivated by neurectomy.Supported by SNF grant no. 3.510-0.86     

Effect of muscular work on the motor function of the stomach and duodenum

Summary The effect of muscle work on the gastric and duodenal motor function was studied in dogs.It was observed that the static stress inhibited the hunger contractions of the stomach and duodenum; the inhibitory effect disappeared as the stress ceased. The static muscle work effect was more pronounced in hunger contractions of the stomach than in those of the duodenum. Under the influence of static stress, the periodic hunger contractions of the stomach varied more extensively than its acid and digestive contractions.Presented by Active Member Acad. Med. Sci. USSR V. N. Chernigovsky     

Convergent inputs from articular,cutaneous and muscle receptors onto ascending tract cells in the cat spinal cord

Summary 1.Responses were recorded from 160 ascending tract cells in segments L4 to L6 of the spinal cord in chloralose anaesthetized, spinalized cats. The tract cells were identified by antidromic activation following stimulation of pathways in the lateral and ventral funiculi at the level of the spinal cord transection at the thoracolumbar junction. Axonal conduction velocities ranged from 9 to 114 m/s. 2. A sample of 152 of the neurones examined could be subdivided according to the distribution of their receptive fields into 49 cells activated just from receptors located in skin (s cells), 17 neurones excited by receptors in deep tissues (d cells), 15 units with a convergent input from receptors in skin and deep tissues (sd cells), and 25 neurones with a convergent input from the knee joint and either skin (sj cells), deep tissues (dj cells) or both (sdj cells). No receptive fields could be demonstrated for the remaining 46 neurones. 3. S and sj cells were found almost exclusively in the dorsal horn, whereas many d, sd, sdj and dj units were in the ventral horn. Almost all of the cells that lacked receptive fields were in the ventral horn or intermediate grey. 4. Ninety-one of 158 cells (56%) demonstrated no background activity. Of these, 43 cells (27%) lacked receptive fields. Many of the silent neurones were in the ventral horn, but some were in the dorsal horn. Of 25 cells having knee joint input, 18 (72%) had background activity. 5. All of the neurones that had a receptive field in the knee joint also had a convergent input from receptors in other tissues. In 3 cases, there was a receptive field in the skin over the foot (sj cells). For 16 cells, receptive fields included not only the knee joint but also skin and deep tissue (sdj cells). Usually, the cutaneous receptive field was near the knee joint, but sometimes it was remote, such as on the foot. The deep receptive fields were chiefly in the muscles of the thigh and/or leg. For 6 dj cells, the receptive fields included not only the knee joint but also deep fields like those of sdj cells. 6. Cutaneous receptive fields were classified as low threshold (cells excited best by innocuous intensities of mechanical stimulation), wide dynamic range (cells activated by weak mechanical stimuli, but the best responses were to noxious stimuli) or high threshold (innocuous stimuli had little effect, but noxious mechanical stimuli produced a vigorous discharge). Similarly, stimulation of the knee joint with weak mechanical stimuli could excite some neurones, while others could be activated by weak or strong articular stimuli but were excited best by noxious stimuli, and still other neurones were activated by knee joint stimuli only if the intensity was noxious. 7. In several instances, contralateral receptive fields were noted. These were generally in deep tissue or in the knee joint. 8. It was concluded that many of the responses to articular stimulation of the spinal cord ascending tract cells examined in this study could have been mediated by the fine afferent fibres that supply the knee joint. Although further work will be required to determine which particular ascending tracts transmit nociceptive information concerning the knee joint, it can be proposed that many of the responses demonstrated here were likely to play a role in either joint pain of in triggering responses associated with joint pain.     

The Involvement of Dopamine in Strengthening Cortical Signals Activating NMDA Receptors in the Striatum (a hypothetical mechanism)

A possible mechanism is proposed for the enhancement/weakening of those cortical signals in the cortex-basal ganglia-thalamus-cortex neural network which induce/do not induce opening of NMDA channels in the spiny neurons of the striatum and which can be regarded as strong/weak in terms of this measure. The mechanism is based on the modulatory influences of dopamine on changes in the efficiency of corticostriatal inputs. In the absence of dopamine, relative increases in the intensity of strong (weak) cortical signals can lead to the induction of long-term potentiation (depression) of corticostriatal synapses. In this case, because of the differently directed influences on thalamic cells of signals passing via strionigral and striopallidal cells, strong signals at the output of the thalamus are weakened, while weak signals are strengthened. Activation of dopamine D₁ (D₂) receptors on strionigral (striopallidal) neurons may facilitate increases in the extent of long-term potentiation/depression (decreases in the extent of long-term potentiation/depression or induction of long-term potentiation/depression). The consequence of this is that strong signals at the output of the thalamus can be strengthened synergistically, while weak signals cab be weakened synergistically. Background cortical signals evoking tonic release of dopamine in the striatum can decrease strengthening because of weakening of the modulatory influence of dopamine on the modification of corticostriatal synapses.     

Hemoglobin heterogeneity under conditions of abnormal erythropoiesis

Experiments on rats showed that changes in the hemoglobin profile during hypoxia are determined by switching of erythropoiesis from the basic to emergency mode. The basic mode of erythropoiesis is typical of the mature organism under normal conditions. The reserve or emergency mode is realized in fetuses, senile animals, and during hypoxia. This mode is characterized by production of large erythrocytes with high content of fetal hemoglobin.     

The ultrastructure of the “excretory” system of ascaris suum larvae

Summary Electron microscope observations of the excretory cell of the infective larva reveal that it contains a large nucleus surrounded by cytoplasm containing numerous organelles, multi-granular bodies, vesicles and granules typical of glandular cells. The proximal region of the excretory duct bears a number of scattered microvilli, on its adluminal surface, and the distal region is lined with a thin multilayered cuticle.In the liver stage larva 2 days after infection, 2 lateral excretory columns are present. These arise from the excretory cell body and extend posteriorly for about half the length of the intestine. Each column contains a narrow longitudinal canal surrounded by cytoplasm rich in mitochondria, granular endoplasmic reticulum, free ribosomes and large vacuoles. Evidence was obtained of the passage of substances through the wall of the canal but their chemical nature was not determined.Further extension of the lateral columns is seen in the 8-day, lung-stage larva, the columns now extending for more than two-thirds the length of the intestine. Their diameter is also increased but their internal structure is essentially similar to that of the 2-day liver-stage larva.The excretory duct which arises immediately anterior to the nucleus has a structure similar to that of the lateral columns for the first half of its length, the microvilli described in the infective larva being absent at this stage. The distal half of the duct is lined with cuticle.     

An improved apparatus for the optical recording of contraction of single heart cells

An optical system for measuring changes in cell length during unloaded contractions of cardiac myocytes is described. A one-dimensional video image of a cell is obtained every 4 ms with a linear photodiode array, which is aligned with the longitudinal axis of the cell. The circuit used to process the image from the photodiode array has a variety of features to aid in the accurate determination of the distance between the ends of the cell, i.e. the cell length. First, the video image of the cell is divided into two windows, one encompassing the front edge of the cell, the other encompassing the rear edge. Other cells or debris beyond the cell edges are excluded. Changes in the general light level, for example as a result of debris floating above the cell, have little effect because within the windows the background light level is subtracted from the signals before they are processed further. To detect the cell edges, the system determines when the signals within the windows exceed (front edge) or drop below (rear edge) chosen threscholds, which are different for the front and rear edges. The system has memory and it identifies the rear edge of the cell as the last time the signal falls below the threshold; because of this bright spots within the cell are not mistaken for the end of the cell. The system has hysteresis, which enables it to ignore small fluctuations in brightness around the threshold. The system is easy to use, accurate, readily calibrated, and it has good spatial and time resolution (about 0.25 m and 4 ms respectively).     

Investigation of the “valency” of antibodies by means of azoproteins

Summary The valency of antibodies was studied by the method of exhaustion of antisera against mono-and diazoproteins, and subsequent cross reactions both with the antibodies left over in the supernatant fluid of the serum and with the precipitating and nonprecipitating antibodies isolated from the precipitate.It was proved that the antibodies interact with the antigens as multivalent compounds.The valency determined with regard to the azoproteins is dependent upon the number of groups introduced.Thus, bivalent antibodies correspond to monoazoproteins and trivalent ones to diazoproteins.The valency of antibodies is, evidently, determined by the structural similarity of the heterologous and the immunizing antigens as well as by the less complete specific conformity between the individual structural peculiarities of the antigen and its antibody.From the Tashkent Pharmaceutical Institute (Director-Docent M. A. Azizov)Presented by Active Member AMN SSSR N. N. Zhukov-Verezhnikov     

Oncogenic activity of the BK type of human papova virus in inbred rat strains

Summary The oncogenicity of the human polyomavirus BK (BKV) was tested in newborn inbred rats.It was found that the tumor rate was negatively correlated with the levels of T antibody 3 months after inoculation and the frequency of animals with detectable T antibodies 1.5 months after inoculation.By contrast, no influence of viral HI titers on the tumor rates was found. Thymectomy of animals resulted in most experiments in increased tumor rates. Inoculation with BKV of animals later than 24 hours after birth yielded a decrease of tumor rates.The results obtained suggest that T antibody titers present at a critical time after inoculation are associated with low oncogenicity of BKV.The oncogenicity of BKV was comparatively tested in rat strains possessing the allele l or the allele a, respectively. The oncogenicity was significantly higher in rats with the allele l than in rats with the allele a. Rats with the allele l showed lower T antibody response than rats with the allele a.These differences could be explained by the finding that cells of a origin showedin vitro a higher percentage of T antigen bearing cells than did cells of a strain possessing the allele l. In comparison to previous results obtained with BKV inoculated outbred WISTAR rats, the oncogenicity of comparable BKV doses in inbred rats was generally higher and the latency period of tumor manifestation shortened.     

Summation and adaptation in stimulation of the motor cortex in adult and newborn animals

Summary In rabbits and their progeny an investigation was made of summation and adaptation of the neurones of the motor cortex; unipolar stimulation was used, and the muscular response recorded. Two types of summation curves were found: exponential and Y-shaped,, and were related to the direct and indirect summation of stimulation. In adults, Y-shaped summation curves were more frequent, whereas in rabbits aged 24 h exponential curves preponderted. We found very little capacity for adaptation at any age.(Presented by Active Member AMN SSSR A. F. Turom) Translated from Byulleten Éksperimental'noi Biologii i Medisiny, Vol. 55, No. 6, pp. 3–7, June, 1963     

Disturbance of delayed match-to-sample in macaques by tetanization of anterior commissure versus limbic system or basal ganglia

Summary Three pig-tailed macaques were trained to select (match) from a pair of colored images that which they had seen (sample) and responded to 5–15 s previously. The anterior commissure (AC) and/or its radiation, various loci in basal ganglia, hippocampal formation and control areas, (splenium of corpus callosum, precentral gyrus, insular cortex), totalling 40 loci, were each tetanized for 4 s during presentation of the sample image, during the delay period, or when the monkey was required to select the matching image. For several loci in the hippocampal formation tetanization at any phase of the task reduced matching to chance levels and gave evidence of electrical after-discharge; but other comparable hippocampal loci had little or no effect. Response to sample or match stimuli were absent during tetanization of basal ganglia or anterior commissure. When finally made, upon cessation of tetanization, responses were equally correct for basal ganglia and control sites, but for AC were at chance levels.     

The distribution of lanthanum in tight junctions of the kidney tubule

Summary The penetration of either ionic or colloidal lanthanum into the tight junctions of different tubular segments of the rat kidney was studied with the electron microscope. After perfusing the tracer through the aorta it was found that ionic and colloidal lanthanum penetrated the tight junctions of both the proximal and distal convoluted tubules, while the junctions of the collecting tubules were free of tracer. An attempt to correlate junctional tightness and electrical resistance in these epithelia is presented.     

Molecular-epigenetic aspects of phylo- and ontogenetic memory

The problem of biological memory is discussed, and the theoretical unity of all types of memory-phylogenetic, immunological, and neuronal — is emphasized. This unity consists of the fact that the origin of anything new in living systems during phylo- or ontogenesis can be described within the framework of three principles: the generator of variability of templates, the phenotypic expression of templates, and the effective selection of templates. Here also lies the essence of the Darwinian approach to the problem of memory in general. The indicated three principles characterize the processes of transformation of feedback information in living nature both at the population level and at the level of individual living systems. They show how a backflow of information from the external environment to the organisms, leading to the formation of new adaptive responses in the course of ontogenesis, can be accomplished. Without contradicting the fundamentals of molecular biology and molecular genetics, they permit an explanation of the appearance of new adaptations, the accumulation of individual experience in ontogenesis, an unforeseen inborn genetic program.I should like to express my deep gratitude to Professor I. P. Ashmarin for his critical discussion of this work.Translated from Zhurnal Évolyutsionnoi Biokhimii i Fiziologii, Vol. 13, No. 1, pp. 3–10, January–February, 1977.     

The growth of a primary tumor (sarcoma M-1) during the training of rats to hypoxia in the low pressure chamber

Summary The effect of hypoxic training of rats on the growth of transplantable tumors (sarcoma M-1) was studied in experiments involving 161 animals. In training the rats at an altitude of 6,000 m, the tumor growth was delayed by 18.6 per cent. With the rise of the training altitude there is a progressively increasing development of the tumor growth-inhibiting mechanisms. At the maximal altitude of training (10,750m) the tumor growth inhibition reached 57.5%.(Presented by Active Member, Academy of Medical Sciences, USSR, V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 51, No. 6, pp. 73–76, June, 1961