Female-induced sexual arousal in male mice and rats: behavioral and testosterone response

Exposure of a male mouse to a female mouse separated from it by a holed partition induced specific behavior and an increase in blood testosterone in the male. The male made more approaches to the partition and spent more time at it. The time spent by the male mouse over the first 10 min at the partition, behind which an estrus female was placed, was increased sixfold compared to the time spent by a male mouse exposed to the vacant neighboring compartment; and 1.5-fold compared to that spent by a male mouse exposed to a nonreceptive female or a male. Increased blood testosterone level was detected at 20 min of exposure to a receptive female in winter and at 40 min in summer. No variation in blood testosterone levels in the male mouse exposed to a nonreceptive female or a male was observed. Similar response to a receptive female placed in the neighboring compartment was shown in a male rat. The time spent by the male rat at the partition was 12 times higher when there was an estrus female behind it than in control. Blood testosterone in the male rat increased in response to a female rat and did not change in response to a male rat indicating female-induced motivation. It was concluded that the partition time might serve as a quantitative measure of sexual motivation in the males and that the model of female-induced sexual arousal used was suitable for studying both motivational and hormonal components of sexual arousal in male mice and rats.     

Elimination of suppressor T-cells in mice undergoing a graft-versus-host reaction expressed by increased response to polyvinylpyrrolidone (PVP).

Mice undergoing a mild GVHR exhibited an enhanced response to PVP considered to be independent of T-helper function and simultaneously, a decreased response to SRBC, known to be T-cell dependent. Such mice had a reduced number of T cells in their spleens expressed by a lower reactivity to T-lectins PHA and Con A and by a decrease in the number of cells killed by anti θ serum. These mice did not show, however, a substantial change in the activity of B lymphocytes contained in their spleens, since the PFC and the mitogenic response to LPS, as well as the number of immunoglobulin bearing cells were similar to that of controls. These results suggest that the enhanced response to PVP in mice undergoing a mild GVHR is a result of the elimination of a certain T-cell population which seems to regulate the immune response to this antigen.     

The extinction context enables extinction performance after a change in context

One experiment with human participants determined the extent to which recovery of extinguished responding with a context switch was due to a failure to retrieve contextually controlled learning, or some other process such as participants learning that context changes signal reversals in the meaning of stimulus-outcome relationships. In a video game, participants learned to suppress mouse clicking in the presence of a stimulus that predicted an attack. Then, that stimulus underwent extinction in a different context (environment within the game). Following extinction, suppression was recovered and then extinguished again during testing in the conditioning context. In a final test, participants that were tested in the context where extinction first took place showed less of a recovery than those tested in a neutral context, but they showed a recovery of suppression nevertheless. A change in context tended to cause a change in the meaning of the stimulus, leading to recovery in both the neutral and extinction contexts. The extinction context attenuated that recovery, perhaps by enabling retrieval of the learning that took place in extinction. Recovery outside an extinction context is due to a failure of the context to enable the learning acquired during extinction, but only in part.     

Rock-scissors-paper and the survival of the weakest.

In the children's game of rock-scissors-paper, players each choose one of three strategies. A rock beats a pair of scissors, scissors beat a sheet of paper and paper beats a rock, so the strategies form a competitive cycle. Although cycles in competitive ability appear to be reasonably rare among terrestrial plants, they are common among marine sessile organisms and have been reported in other contexts. Here we consider a system with three species in a competitive loop and show that this simple ecology exhibits two counter-intuitive phenomena. First, the species that is least competitive is expected to have the largest population and, where there are oscillations in a finite population, to be the least likely to die out. As a consequence an apparent weakening of a species leads to an increase in its population. Second, evolution favours the most competitive individuals within a species, which leads to a decline in its population. This is analogous to the tragedy of the commons, but here, rather than leading to a collapse, the 'tragedy' acts to maintain diversity.     

Conformational dynamics of DnaB helicase upon DNA and nucleotide binding: analysis by intrinsic tryptophan fluorescence quenching

DnaB helicase of E. coli unwinds duplex DNA in the replication fork using the energy of ATP hydrolysis. We have analyzed structural and conformational changes in the DnaB protein in various nucleotides and DNA bound intermediate states by fluorescence quenching analysis of intrinsic fluorescence of native tryptophan (Trp) residues in DnaB. Fluorescence quenching analysis indicated that Trp48 in domain alpha is in a hydrophobic environment and resistant to fluorescence quenchers such as potassium iodide (KI). In domain beta, Trp294 was found to be in a partially hydrophobic environment, whereas Trp456 in domain gamma appeared to be in the least hydrophobic environment. Binding of oligonucleotides to DnaB helicase resulted in a significant attenuation of the fluorescence quenching profile, indicating a change in conformation. ATPgammaS or ATP binding appeared to lead to a conformation in which Trp residues had a higher degree of solvent exposure and fluorescence quenching. However, the most dramatic increase of Trp fluorescence quenching was observed with ADP binding with a possible conformational relaxation. Site-specific Trp --> Cys mutants of DnaB helicase demonstrated that conformational change upon ADP binding could be attributed exclusively to a conformational transition in the alpha domain leading to an increase in the solvent exposure of Trp48. However, formation of DnaB.ATPgammaS.DNA ternary complex led to a conformation with a fluorescence quenching profile similar to that observed with DnaB alone. The DnaB.ADP.DNA ternary complex produced a quenching curve similar to that of DnaB.ADP complex pointing to a change in conformation due to ATP hydrolysis. There are at least four identifiable structural/conformational states of DnaB helicase that are likely important in the helicase activity. The noncatalytic alpha domain in the N-terminus appeared to undergo the most significant conformational changes during nucleotide binding and hydrolysis. This is the first reported elucidation of the putative role of domain alpha, which is essential for DNA helicase action. We have correlated these results with partial structural models of alpha, beta, and gamma domains     

An as-1-like motif controls the level of expression of the gene for the pathogenesis-related protein 1a from tobacco

Pathogenesis-related proteins of group 1 (PR-1) are strongly induced in plants by pathogen attack, exposure of the plants to (acetyl)salicylic acid (ASA, SA), and by developmental cues. Functional analysis of the PR-1a promoter identified a region of 139 bp (from -691 to -553) mediating expression of the GUS reporter gene in response to ASA. Inspection of this region revealed two TGACG elements reminiscent of activation sequence-1 (as-1). Recently, as-1 has been reported to be responsive to SA in the context of the CaMV 35S RNA promoter. To address the question of whether the as-1-like sequence may be of functional significance for the expression of the PR-1a gene, gel shift assays were performed with TGA1a, a protein been shown to interact with as-1 in vitro. TGA1a was found to bind to the PR-1a as-1-like sequence with similar specificity and affinity as to as-1. Furthermore, mutations were introduced in the as-1-like sequence in the context of the inducible 906 bp PR-1a promoter which are impaired in binding TGA1a in vitro. Significantly reduced levels of GUS reporter gene activity were obtained with the mutant promoter regions as compared to the wild-type PR-1a promoter in response to all stimuli in transgenic tobacco plants. Yet, mutation of the as-1-like sequence did not abolish induction of reporter gene expression. Taken together, these results suggest that the level of expression of the tobacco PR-1a gene is controlled by an as-1-like sequence motif in the PR-1a upstream region, possibly interacting with a factor related to TGA1a.     

Detection of protease activity in the wetted surface of gelatin-coated electrodes in air by AC impedance spectroscopy

As a step towards developing a biosensor which can detect airborne protease droplets, a biosensor which had previously been developed to detect protease in solution is shown to be capable of detecting different concentrations of protease in liquid films on the sensor surface in air. The biosensor measured impedance change due to proteolytic digestion of its gelatin coating. In saturated air there was a rise in impedance, with a loss in weight of the gelatin, in proportion to collagenase concentration. The addition of glycerol to the gelatin caused a lower impedance response and smaller loss in weight. A critical thickness of the gelatin layer prior to a more rapid change in the rate of impedance was noted, with and without the addition of glycerol. In low air humidity (40%), with gelatin, all collagenase concentrations produced a very similar rapid increase in impedance. However, with glycerol-enhanced gelatin, there was a clear distinction between the extent of impedance change with different collagenase concentrations. The application of these findings for use in the field of bioaerosol sampling is discussed.     

Effects of cultivation practice on floristic and flowering diversity of spontaneously growing plant species on arable fields

In the past, the floristic diversity of arable fields has been described in terms of species diversity (SD) and their degree of coverage (C), but never in combination with the recording of the actually flowered species (FS) and their flowering intensity (FI) to striking differences in the cultivation methods on arable land. In relation to SD and C, however, FS and FI may provide important additional information on the functional biodiversity of fields. The aim was therefore to investigate the effects of (a) conventional, (b) organic, and (c) smallholder (never application of herbicides) on the floristic diversity. Using a region in Germany, we investigated SD, C, FS, and FI synchronously in (a), (b), and (c), by 356 vegetation surveys (5 × 5 m plots) conducted in spring and summer in 2019 in winter cereals. Statistical tests were used to analyze the differences between (a), (b), and (c). The medians were used to compare the floristic diversity of (a), (b), and (c) and finally relationships of FS and FI to SD were analyzed in relation to the cultivation methods. Significant differences in SD, C, FS, and FI were found between the (a), (b), and (c) in spring and summer characterized by sharp declines from (c) to (b) to (a). A drastic reduction in floristic diversity from (c) 100 to (b) 52 to (a) 3 was determined. Plants in flower (FS, FI) were very poorly in (a), moderately well to well in (b), and well to very well represented in (c). (C) to (a) was characterized by a sharp decline and from (a) to (b) by sharp increase in floristic diversity. With current acreage proportions of (a) in mind, this would affect, about one third of land area in Germany, associated with a drastic reduction in functional biodiversity for insects.     

Threshold effect and tissue specificity. Implication for mitochondrial cytopathies

Mitochondrial cytopathies present a tissue specificity characterized by the fact that even if a mitochondrial DNA mutation is present in all tissues, only some will be affected and induce a pathology. Several mechanisms have been proposed to explain this phenomenon such as the appearance of a sporadic mutation in a given stem cell during embryogenesis or mitotic segregation, giving different degrees of heteroplasmy in tissues. However, these mechanisms cannot be the only ones involved in tissue specificity. In this paper, we propose an additional mechanism contributing to tissue specificity. It is based on the metabolic expression of the defect in oxidative phosphorylation (OXPHOS) complexes that can present a biochemical threshold. The value of this threshold for a given OXPHOS complex can vary according to the tissue; thus different tissues will display different sensitivities to a defect in an OXPHOS complex. To verify this hypothesis and to illustrate the pathological consequences of the variation in biochemical thresholds, we studied their values for seven OXPHOS complexes in mitochondria isolated from five different rat tissues. Two types of behavior in the threshold curves can be distinguished corresponding to two modes of OXPHOS response to a deficiency. We propose a classification of tissues according to their type of OXPHOS response to a complex deficiency and therefore to their threshold values.     

A prototype model structure for mixed microbial populations in homogeneous food products

An important factor which has not been included in many models in the field of predictive microbiology is the influence of a background of microflora in a food product. It is however generally known that the growth of a microorganism as a pure culture can be substantially different from its growth in a mixed culture, due to microbial interactions. Because of the importance of these interactions and the lack of suitable modeling techniques in the field of predictive microbiology to describe them, the potential of models in other research fields-namely ecology-to deal with interactions is explored in previous work of the authors. However, a model structure for microbial growth in food products cannot simply be copied from those elaborated in ecology. The structure of a predictive growth model is indeed typical, primarily due to the explicit modeling of a lag phase. The current paper proposes a prototype model structure for growth of mixed microbial populations in homogeneous food products. The model is able to describe a lag phase and reduces to a classical predictive growth model in the special case of single-species growth.     

不同小麦品种的根系生理特性,磷的吸收及利用效率对产量影？…

不同小麦品种的分蘖数、叶片数、干物量与根系总吸收面积及活跃吸收面积呈正相关,在低磷处理的相关性均达到显著水平。此各品种收获得期的干物量及籽粒产量亦与株吸磷量及利用效率呈正相关。通过各因素的比较,鉴定出在低磷条件下可获较高产量的品种。     

Delivery of wingless to the ventral mesoderm by the developing central nervous system ensures proper patterning of individual slouch-positive muscle progenitors

During the development of any organism, care must be given to properly pattern gene expression in temporally and spatially regulated manners. This process becomes more complex when the signals that regulate a target tissue are produced in an adjacent tissue and must travel to the target tissue to affect gene expression. We have used the developing somatic mesoderm in Drosophila as a system in which to examine this problem. Our investigation uncovered a novel mechanism by which Wingless (Wg) can travel from its source in the ectoderm to regulate the expression of the somatic muscle founder identity gene, slouch, in the ventral mesoderm. Delivery of Wg to the mesoderm by the developing Central Nervous System (CNS) exploits the stereotypic formation of this tissue to provide high Wg levels to Slouch founder cell cluster II in a temporally specific manner. Coordinated development of these tissues provides a reliable mechanism for delivering high Wg levels to a subset of mesodermal cells. It also provides a means for one signaling pathway to be used reiteratively throughout development to impart unique positional and character information within a target field.     

Autonomic responses of autistic children to people and objects

Several recent lines of inquiry have pointed to the amygdala as a potential lesion site in autism. Because one function of the amygdala may be to produce autonomic arousal at the sight of a significant face, we compared the responses of autistic children to their mothers' face and to a plain paper cup. Unlike normals, the autistic children as a whole did not show a larger response to the person than to the cup. We also monitored sympathetic activity in autistic children as they engaged in a wide range of everyday behaviours. The children tended to use self-stimulation activities in order to calm hyper-responsive activity of the sympathetic ('fight or flight') branch of the autonomic nervous system. A small percentage of our autistic subjects had hyporesponsive sympathetic activity, with essentially no electrodermal responses except to self-injurious behaviour. We sketch a hypothesis about autism according to which autistic children use overt behaviour in order to control a malfunctioning autonomic nervous system and suggest that they have learned to avoid using certain processing areas in the temporal lobes.     

A potent effect of observational learning on chimpanzee tool construction

Although tool use occurs in diverse species, its complexity may mark an important distinction between humans and other animals. Chimpanzee tool use has many similarities to that seen in humans, yet evidence of the cumulatively complex and constructive technologies common in human populations remains absent in free-ranging chimpanzees. Here we provide the first evidence that chimpanzees have a latent capacity to socially learn to construct a composite tool. Fifty chimpanzees were assigned to one of five demonstration conditions that varied in the amount and type of information available in video footage of a conspecific. Chimpanzees exposed to complete footage of a chimpanzee combining the two components to retrieve a reward learned to combine the tools significantly more than those exposed to more restricted information. In a follow-up test, chimpanzees that constructed tools after watching the complete demonstration tended to do so even when the reward was within reach of the unmodified components, whereas those that spontaneously solved the task (without seeing the modification process) combined only when necessary. Social learning, therefore, had a powerful effect in instilling a marked persistence in the use of a complex technique at the cost of efficiency, inhibiting insightful tool use.     

Apolar growth of Neurospora crassa leads to increased secretion of extracellular proteins

Protein secretion in filamentous fungi has been shown to be restricted to actively growing hyphal tips. To determine whether an increase in the amount of growing surface area of a fungus can lead to an increase in the amount of protein secretion, we examined secretion in a temperature-sensitive Neurospora crassa mcb mutant that shows a loss of growth polarity when incubated at restrictive temperature. Incubation of the mcb mutant at restrictive temperature results in a three- to fivefold increase in the level of extracellular protein and a 20-fold increase in carboxymethyl cellulase activity relative to a wild-type strain. A mutation in the cr-1 gene has been shown previously to suppress the apolar growth phenotype of the mcb mutant, and we find that the level of extracellular protein produced by a mcb ; cr-1 double mutant was reduced to that of the wild-type control. Immunolocalization of a secreted endoglucanase revealed that proteins are secreted mainly at hyphal tips in hyphae exhibiting polar growth and over the entire surface area of bulbous regions of hyphae that are produced after a shift of the mcb mutant to restrictive temperature. These results support the hypothesis that secretion of extracellular protein by a filamentous fungus can be significantly increased by mutations that alter growth polarity.     

Searching behaviour and mate recognition by males of the two-spot ladybird beetle, Adalia bipunctata

Abstract. 1. Adult males of the two-spot ladybird beetle, Adalia bipunctata , did not show a functional response to increase in aphid abundance and consumed markedly fewer aphids than do the females.
2. At high densities of prey, females spent more time in area-restricted search than when prey was scarce. Males were always less active than females and they did not respond to an increase in prey abundance by a change in searching behaviour.
3. After a brief encounter with a female, a male showed area-restricted searching behaviour. This behaviour occurred in response to encountering a female's elytra and in particular to a chloroform-soluble component (sex pheromone) present on or in the elytra.
4. Males needed to encounter a female in order to respond to her presence, which indicated the pheromone is a contact pheromone.
5. The searching behaviour of males appeared to be mainly directed towards locating females; that of females towards locating aphids. This difference between the sexes should be taken into account when quantifying the predatory response of ladybirds to aphid abundance in the field.     

Kinetic Effects of Terbium Ions on Muscarinic Acetylcholine Receptors of Murine Neuroblastoma Cells

Preincubation of murine neuroblastoma cells (clone N1E-115) with terbium chloride resulted in a significant potentiation of carbachol-mediated increase in cyclic GMP formation. This effect was accompanied by a shift of the peak response from 30 s to 120 s and a 6-fold decrease in carbachol concentration producing half-maximal responses, in addition to a significant increase in the Hill coefficient. Terbium ions also caused a significant decrease in the affinity and an increase in the maximum binding of [3H]quinuclidinyl benzilate to muscarinic receptors, the change in affinity being mainly due to a decrease in the association rate. Preincubation of cells with 1 mM carbachol for 4 h (the desensitized state of the muscarinic receptor) resulted in a decrease in the ability of terbium to alter [3H]quinuclidinyl benzilate binding. The effects of terbium reported here might be due to its affecting muscarinic receptor-effector coupling, which is considered to be lost upon receptor desensitization.     

Methionine oxidation and aging

It is well established that many amino acid residues of proteins are susceptible to oxidation by various forms of reactive oxygen species (ROS), and that oxidatively modified proteins accumulate during aging, oxidative stress, and in a number of age-related diseases. Methionine residues and cysteine residues of proteins are particularly sensitive to oxidation by ROS. However, unlike oxidation of other amino acid residues, the oxidation of these sulfur amino acids is reversible. Oxidation of methionine residues leads to the formation of both R- and S-stereoisomers of methionine sulfoxide (MetO) and most cells contain stereospecific methionine sulfoxide reductases (Msr's) that catalyze the thioredoxin-dependent reduction of MetO residues back to methionine residues. We summarize here results of studies, by many workers, showing that the MetO content of proteins increases with age in a number of different aging models, including replicative senescence and erythrocyte aging, but not in mouse tissues during aging. The change in levels of MetO may reflect alterations in any one or more of many different mechanisms, including (i) an increase in the rate of ROS generation; (ii) a decrease in the antioxidant capacity; (iii) a decrease in proteolytic activities that preferentially degrade oxidized proteins; or (iv) a decrease in the ability to convert MetO residues back to Met residues, due either to a direct loss of Msr enzyme levels or indirectly to a loss in the availability of the reducing equivalents (thioredoxin, thioredoxin reductase, NADPH generation) involved. The importance of Msr activity is highlighted by the fact that aging is associated with a loss of Msr activities in a number of animal tissues, and mutations in mice leading to a decrease in the Msr levels lead to a decrease in the maximum life span, whereas overexpression of Msr leads to a dramatic increase in the maximum life span.