Inter-relationship of behaviour, faecal testosterone levels and glandular volatiles in determination of dominance in male Blackbuck

The social hierarchy of blackbuck plays a crucial role in mate selection and establishment of hierarchy in order to maintain successful reproduction. The factors that influence dominancy have not been yet investigated in the Indian male blackbuck. Here, we investigated the interrelationships between behaviours (aggressive and scent marking), chemical profiles of preorbital gland secretion and faecal testosterone levels in male blackbuck with special reference to dominance hierarchy. The frequency of aggressive behaviour, preorbital gland scent marking behaviour and faecal testosterone level were significantly higher (P <0.001) in the dominant males than the other males. Among the 43 major volatile compounds identified in the pre-orbital gland posting of dominant and subordinate male Blackbucks, four compounds viz., 2-methyl propanoic acid (I), 2-methyl-4-heptanone (II), 2,7-dimethyl-1-octanol (III) and 1,15-pentadecanediol (IV) were present only in the preorbital gland post of the dominant male during the hierarchy period. The results suggest that male blackbuck preorbital gland marking behaviour is meant to defend the home range or territorial region, and the scent odour suppresses aggression, scent marking, scent production and territorial patrolling of subordinate males. The behavioural expression, level of testosterone and volatile chemical profiles are closely interlinked towards establishment of dominance in the blackbuck. This investigation is the first of its kind to detect establishment of dominance hierarchy based on identification of volatile chemical compounds of preorbital gland and assessment of faecal testosterone in blackbuck.

Buck odor production in the cornual gland of the male goat, Capra hircus– Validation with histoarchitecture, volatile and proteomic analysis

In many animals, glandular secretions or pheromones that possess biological moieties contain messages encoded by the intrinsic smell. In male goats, the cornual gland (a sebaceous gland), may synthesize and excrete relevant chemical components that are responsible for the ‘buck effect’. To test this, cornual glands from freshly-slaughtered male goats (N=6) were subjected to histoarchitecture analysis, to infer about the structural alignment, to the GC–MS analysis for volatile compounds and to SDS–PAGE for protein profiling followed by MALDI-TOF to characterize specific protein bands. The gland possesses sebum, vacuoles and hair follicles inferring its capability to synthesize and extrude the scent. We found 14 volatiles in GC–MS analysis, in which 1-octadecanol might be a putative pheromone of buck odor. We identified seven different proteins in SDS-PAGE. Two proteins, 28 and 33 kDa, were highly matched with DNA mismatch repair protein and Abietadiene synthase, respectively, as inferred from MALDI-TOF. Conclusively, the volatiles identified in the cornual gland suggest that the structural microelements of the gland may synthesize (sebum and vacuoles) and release the key volatiles through the hair follicles. The volatile(s) thus produced in male goats either solely or synergistically may confer the buck odor.

Effect of mutation on aggregation propensity in homology model structures of syntaxin-3 from Homo sapiens.

Perception of molecular mechanism would provide potent additional knowledge on mammalian membrane proteins involved in causing diseases. In human, syntaxin-3 (STX3) is a significant apical targeting protein in the epithelial membrane and in exocytosis process; it also acts as a vesicle transporter by cellular receptor in neutrophils, which is crucial for protein trafficking event. Structurally, syntaxin-3 has hydrophobic domain at carboxyl terminus that directs itself to intra-cellular compartments. In addition, the experimental structure of STX3 is not available and no mutational study has been carried out with natural variants of proteins. Moreover, there is no evidence so far for the natural variant Val286 of STX3 causing any diseases. Hence, in the present study, analyses of residue-based properties of the homology model STX3 were carried out along with mutations at carboxyl terminus of STX3 by implementing protein engineering and in silico approaches. The model structure of STX3 was constructed adopting Modeller v9.11 and the aggregation propensity was analyzed with BioLuminate tool. The results showed that there was reduction in aggregation propensity with point mutation at Val286, instead of Ile, resulting into increasing the structural stability of STX3. In conclusion, the Ccap exposed residue would be a suitable position for further mutational studies, particularly with Val286 of STX3 in human. This approach could gainfully be applied to STX3 for efficient drug designing which would be a valuable target in the cancer treatment.

Preputial gland activates olfactory receptor neurons in rat: Calcium imaging study using laser scanning confocal microscopy.

The rodent preputial gland is one of the major sources of odours and is reported to be involved in several behavioural activities. However, how the preputial gland initiates the olfactory response to manifest the effects is not known. Olfactory receptor neurons (ORNs) present in the olfactory epithelium are involved in the perception of odorant/pheromonal compounds. In the present study, the response of rat ORNs to preputial gland extract was evaluated by calcium imaging analysis. We found that some rat ORNs responded to the preputial gland extract by exhibiting an intracellular calcium response. By contrast, the ORNs did not respond at all to the foot pad extract (control). The results indicated that the substances contained in the preputial gland might interact with a type of receptor expressed in the female rat ORNs, suggested to manifest the behavioural responses, such as social and sexual interactions. This study provided the first evidence of activation of ORNs by the preputial gland extract.

Responsiveness of male rats towards odour of five scent sources of male and female rats

Avaliamos a responsividade comportamental de ratos machos a odores, tanto de ratos machos quanto de fêmeas. Esses odores foram coletados de várias fontes, como glândulas prepuciais, glândulas da bochecha, porçäo ventral do corpo, urina e fezes. Os machos responsivos foram atraídos por cheiros de machos, principalmente da porçäo ventral do corpo, da urina e das fezes. Os machos näo foram atraídos pelos odores masculinos das glândulas prepuciais e glândulas da bochecha. Além disso, os machos responsivos foram atraídos pelos vários odores das fêmeas. Dentre as cinco fontes odoríferas examinadas, os odores das fezes, urina e porçäo ventral do corpo apresentaram alta significância de atraçäo.

Stud male protection of implantation in food-deprived mice: evaluation of status of ovarian hormones

A falha de implantaçäo em camundongos recém-inseminados induzida por privaçäo alimentar de 48 horas, iniciada às 9 horas no quarto dia após o coito, é evitada pela exposiçäo aos machos. Na presente investigaçäo, estudou-se o efeito da privaçäo alimentar, bem como a influência da presença dos machos durante a privaçäo alimentar nos esteróides ovarianos. Estudos radioimunológicos revelaram que estradiol e testosterona näo foram alterados significativamente nas fêmeas privadas de alimento, independente da presença ou ausência do macho, o que foi comparável ao visto em fêmeas sem privaçäo alimentar. No entanto, o nível sérico de progesterona nas fêmeas privadas foi significativamente reduzido. Por outro lado, näo houve reduçäo no nível de progesterona nas fêmeas privadas de alimento quando em presença dos machos, como ocorreu nas fêmeas controles, i.e., sem jejum. Os resultados suportam a hipótese de que a liberaçäo de prolactina hipofisária, com conseqüente diminuiçäo no desenvolvimento de corpo lúteo funcional, seja o fator endócrino primário na falha de implantaçäo em camundongos com estresse nutricional. Além disso, estes resultados indicam que a presença dos machos contrapöe o fator acima nas fêmeas privadas de alimento.