Effect of dimethoate and fenvalerate on conditioned avoidance and passive avoidance responses

Dimethoate at 24.75 and 49.5 mg/kg (i.e., 1/10 and 1/5th LD50 respectively) impaired the learning process and retrieval of memory in rats while it did not affect permanent memory. Fenvalerate / 10.12 and 20 mg/kg (i.e., 1/20 and 1/10th LD50 respectively) had no effect on learning process, retrieval of memory and permanent memory traces.     

Prevention and avoidance of congenital malformations

Many congenital abnormalities do not have either a Mendelian pattern of inheritance or an identifiable chromosome abnormality and are described as 'multifactorial' as it is assumed they are determined by several genes, each with added effects and modified to a greater or lesser extent by environmental factors. They include spina bifida and anencephaly, cleft lip or cleft palate or both, congenital heart defect and congenital dislocation of the hip, and they constitute a major community health problem. Developments in genetics, biochemistry and cytogenetics have presented new approaches to the prevention and avoidance of congenital abnormalities. The approaches available for the avoidance of congenital malformations include the avoidance of harmful environmental factors, the screening of the newborn and early treatment, genetic counselling and antenatal monitoring with selective termination. The prevention of neural-tube defects in 'high risk' mothers can be achieved by periconceptional vitamin supplementation. In Northern Ireland, of 438 fully supplemented women, only 4 (0.98%) infants or fetuses among 407 infants and fetuses examined had a neural-tube defect, whereas of 356 unsupplemented women, 16 (4.7%) infants or fetuses among 337 infants or fetuses examined had a neural-tube defect.     

Risk avoidance and nesting strategies

Gillespie (1974,1975) has shown that selection will tend to minimize variance in offspring number. It is shown that this effect is due to selection maximizing the average number of surviving offspring when there is density-dependent survival, and that it is unnecessary to invoke principles such as minimizing the variability of fitness (Real, 1980). The effect of this principle of selecting for laying several small clutches rather than one large clutch when there is predation on whole clutches is investigated. It is found that the selection pressure is weak, contrary to the conclusion of Rubenstein (1982), and is unlikely to be of evolutionary importance.     

Inbreeding avoidance behaviors

Inbreeding is defined as mating between individuals related by common ancestry. Thus, the degree to which a particular mating is inbred depends on how far back in a pedigree one begins counting common ancestors. In general practice, the term inbreeding is used to describe mating between close relatives (first cousins or closer). Animal breeders have known for centuries that inbreeding causes a loss of constitutional vigor and fertility in domestic livestock. A growing literature now demonstrates that the offspring of matings between close relatives in species of undomesticated birds and mammals are less fit than outbred offspring. The deleterious consequences of inbreeding suggest the possibility that many species have evolved behaviors that lower the frequency of inbreeding.     

Bacterial avoidance of phagocytosis

Phagocytosis constitutes the primary line of host innate and adaptive defence against incoming microbial pathogens, providing an efficient means for their removal and destruction. However, several virulent bacteria that do not function as intracellular pathogens have evolved mechanisms to avoid and prevent phagocytosis that constitute an essential part of their pathogenic capacity. Some of these mechanisms include preventing recognition by phagocytic receptors or blocking uptake by professional phagocytes. Recently, the molecular mechanisms of such antiphagocytic properties have been elucidated for some pathogens. Such mechanisms illustrate the diversity of mechanisms bacterial pathogens use to avoid phagocytic uptake.     

Adaptive avoidance of reef noise

Auditory information is widely used throughout the animal kingdom in both terrestrial and aquatic environments. Some marine species are dependent on reefs for adult survival and reproduction, and are known to use reef noise to guide orientation towards suitable habitat. Many others that forage in food-rich inshore waters would, however, benefit from avoiding the high density of predators resident on reefs, but nothing is known about whether acoustic cues are used in this context. By analysing a sample of nearly 700,000 crustaceans, caught during experimental playbacks in light traps in the Great Barrier Reef lagoon, we demonstrate an auditory capability in a broad suite of previously neglected taxa, and provide the first evidence in any marine organisms that reef noise can act as a deterrent. In contrast to the larvae of species that require reef habitat for future success, which showed an attraction to broadcasted reef noise, taxa with a pelagic or nocturnally emergent lifestyle actively avoided it. Our results suggest that a far greater range of invertebrate taxa than previously thought can respond to acoustic cues, emphasising yet further the potential negative impact of globally increasing levels of underwater anthropogenic noise.     

Inbreeding avoidance in animals

The phenomenon of inbreeding depression is well documented and behavioral adaptations for inbreeding avoidance have been described. However, there is debate over whether inbreeding depression is always an important selective force on behavior. Here, we summarize recent evidence for inbreeding depression under natural conditions, review inbreeding avoidance mechanisms, and discuss how these are influenced by social structure. We also examine the idea that animals have evolved mechanisms to avoid outbreeding.     

Inbreeding avoidance in chimpanzees

In a community of chimpanzees in Gombe National Park, females' associations with their previous closest male associates (usually maternal siblings) dropped abruptly when they commenced full oestrous cycles, in some cases because the females changed their range within their natal community. Sexual activity was very infrequent between maternal siblings and between mothers and sons. Whereas males remained in their natal community all their lives, most or all females transferred to other communities during adolescence either permanently or temporarily. Inter-community transfer by females apparently resulted from attraction to unfamiliar males. Thus inbreeding appears to be avoided in this species as a consequence of reduced sexual attraction between individuals who were familiar with each other in immaturity.     

Comparison and avoidance of toxicity of penetrating cryoprotectants

The objective of this study was to elucidate the toxicity of widely used penetrating cryoprotective agents (CPAs) to mammalian oocytes. To this end, mouse metaphase II (M II) oocytes were exposed to 1.5 M solutions of dimethylsulfoxide (DMSO), ethylene glycol (EG), or propanediol (PROH) prepared in phosphate buffered saline (PBS) containing 10% fetal bovine serum. To address the time- and temperature-dependence of the CPA toxicity, M II oocytes were exposed to the aforementioned CPAs at room temperature (RT, ～23°C) and 37°C for 15 or 30 minutes. Subsequently, the toxicity of each CPA was evaluated by examining post-exposure survival, fertilization, embryonic development, chromosomal abnormalities, and parthenogenetic activation of treated oocytes. Untreated oocytes served as controls. Exposure of MII oocytes to 1.5 M DMSO or 1.5 M EG at RT for 15 min did not adversely affect any of the evaluated criteria. In contrast, 1.5 M PROH induced a significant increase in oocyte degeneration (54.2%) and parthenogenetic activation (16%) under same conditions. When the CPA exposure was performed at 37°C, the toxic effect of PROH further increased, resulting in lower survival (15%) and no fertilization while the toxicity of DMSO and EG was still insignificant. Nevertheless, it was possible to completely avoid the toxicity of PROH by decreasing its concentration to 0.75 M and combining it with 0.75 M DMSO to bring the total CPA concentration to a cryoprotective level. Moreover, combining lower concentrations (i.e., 0.75 M) of PROH and DMSO significantly improved the cryosurvival of MII oocytes compared to the equivalent concentration of DMSO alone. Taken together, our results suggest that from the perspective of CPA toxicity, DMSO and EG are safer to use in slow cooling protocols while a lower concentration of PROH can be combined with another CPA to avoid its toxicity and to improve the cryosurvival as well.     

Drought avoidance byCyperus rotundus

Cyperus rotundus L. is a hygrophilous plant, but it flourishes well even in the Indian desert. Higher bound water, hygroscopic capacity, % dry matter, lower desiccation rate and volume to mass ratio, development of thick sclerenchymatous layer, presence of cortical vascular bundles and endodermis-like layer appear to be the factors responsible for such adaptation.     

Social factors and the neurobiology of pathogen avoidance

Although the evolutionary causes and consequences of pathogen avoidance have been gaining increasing interest, there has been less attention paid to the proximate neurobiological mechanisms. Animals gauge the infection status of conspecifics and the threat they represent on the basis of various sensory and social cues. Here, we consider the neurobiology of pathogen detection and avoidance from a cognitive, motivational and affective state (disgust) perspective, focusing on the mechanisms associated with activating and directing parasite/pathogen avoidance. Drawing upon studies with laboratory rodents, we briefly discuss aspects of (i) olfactory-mediated recognition and avoidance of infected conspecifics; (ii) relationships between pathogen avoidance and various social factors (e.g. social vigilance, social distancing (approach/avoidance), social salience and social reward); (iii) the roles of various brain regions (in particular the amygdala and insular cortex) and neuromodulators (neurotransmitters, neuropeptides, steroidal hormones and immune components) in the regulation of pathogen avoidance. We propose that understanding the proximate neurobiological mechanisms can provide insights into the ecological and evolutionary consequences of the non-consumptive effects of pathogens and how, when and why females and males engage in pathogen avoidance.     

The evolution and functional significance of incest avoidance

The origin and evolution of outbreeding is discussed in the light of the most recent genetical observations and theoretical developments in ethology. Rather than problems resulting from the expression of recessive deleterious genes, small-population genetic stochastic processes and the resulting homosis are viewed as the primary fitness-limiting features of inbreeding populations. With evolution of biparental reproduction, selection favored the reproductive potential of individuals exhibiting a genetically adopted, behavioral aversion to mating with parents, siblings, and offspring. The human incest taboo is regarded as a cultural epiphenomenon following from the general biological inclination to outbreed.     

Animal models of social avoidance and social fear

Social fear and avoidance of social situations represent the main behavioral symptoms of social anxiety disorder (SAD), a highly prevalent anxiety disorder that is poorly elucidated and has rather unsatisfactory therapeutic options. Therefore, animal models are needed to study the underlying etiology and pathophysiology of SAD and to verify the efficacy of possible novel treatment approaches. In this review, we describe and discuss the most important paradigms that have been shown to induce social avoidance and fear in rodents, including foot shock exposure, restraint stress, social isolation, social instability, social defeat, conditioned defeat, social defeat/overcrowding, chronic subordinate colony housing, chronic mild stress, maternal separation and social fear conditioning. We also describe some of the behavioral paradigms used to assess social avoidance and fear in rodents, including the social interaction test, the social preference-avoidance test, the social approach-avoidance test, the three-chambered social approach test, the partition test and the modified Y-maze test. We focus on the behavioral alterations these paradigms induce, especially on social interaction, general anxiety and depressive-like behavior given that SAD is strongly comorbid with anxiety and affective disorders.     

Self-protective motivation and avoidance of heuristically threatening outgroups

Because hostile outgroup members have been a recurrent source of danger, self-protective motivation leads people to display psychological processes that reduce vulnerability to outgroup threats. The current research examines the consequences of self-protective motivation for intergroup behavior. The current research provides evidence that self-protective motivation causes individuals to automatically avoid heuristically threatening outgroup members. Across two studies, priming self-protective motivation led White participants to display faster avoidance behaviors when presented with images of Black individuals (members of an outgroup culturally stereotyped as violent) than White individuals (members of the ingroup) and Asian individuals (members of an outgroup not stereotyped as violent). This research sheds light on the way in which evolved mechanisms interact with cultural cognitions to shape intergroup behavior.