Ventral Marking Research Articles

The rat Downunder (Du) coat color mutation is associated with eye anomalies and embryonic lethality and maps to a 3.9-Mb region on chromosome 3.

Rodent coat color genes have been studied as a bioresource to understand developmental and cellular processes. The Downunder rat is a fancy variety with a marking on its belly that runs from the neck to the breech and appears to mirror the dorsal hooded marking. Here, we established a congenic strain carrying the Downunder (Du) gene in an F344 genetic background. In addition to the ventral marking, Du/+ rats exhibit anophthalmia or microphthalmia with incomplete penetrance. Du/Du embryos die in the early stages of organogenesis. Genetic linkage analysis mapped the Du gene to rat chromosome 3 and haplotype mapping with congenic rats localized the Du locus to a 3.9-Mb region. The Du locus includes two functional genes, glycosyltransferase-like domain-containing 1 (Gtdc1) and zinc finger E-box binding homeobox 2 (Zeb2). Although we found no functional variation within any of Zeb2's exons or intron-exon boundaries, Zeb2 mRNA levels were significantly lower in Du/+ rats compared with wild-type rats. It is known that melanocyte-specific Zeb2 deletion results in the congenital loss of hair pigmentation in mice. Taken together, our results indicate that the Du mutation exerts pleiotropic effects on hair pigmentation, eye morphology, and development. Moreover, the Zeb2 gene is a strong candidate for the Du mutation.

GENETIC BASIS AND EVOLUTIONARY SIGNIFICANCE OF VENTRAL SKIN COLOR MARKINGS IN NORTH ATLANTIC RIGHT WHALES (EUBALAENA GLACIALIS)

AbstractApproximately one third of the North Atlantic right whale population has white ventral skin patches. Most white‐marked animals have both a belly and a chin patch, and the distribution of white pigment suggests that the patches represent a single ventral marking that varies in size and location. Population frequencies and cow‐calf inheritance patterns indicate that the white mark is an autosomal recessive trait. There is no evidence to suggest that ventral coloration patterns are currently under selection. White‐marked and black cows appear to experience similar levels of reproductive success based on calving intervals and length of sighting histories. Also, white‐marked animals were equally common among cows and nulliparous adult females and among live vs. dead animals. Male reproductive success could not be tested because calf paternity is not known; white‐marked and black males exhibit similar survival rates. White‐marked cows were more common among females that took some or all of their calves to the Bay of Fundy summer nursery area compared to females that did not visit Fundy. This suggests that female habitat‐use patterns may influence nuclear gene flow. Increased sample sizes and additional markers are needed to further investigate gene flow.

Behavioural effects of neocortical and cingulate lesions in the Mongolian gerbil

The experiments examine the effects of cortical lesions on a variety of behaviours in the Mongolian gerbil ( Meriones unguiculatus). Gerbils with either large anterior or posterior lesions were compared with normal gerbils by administering a battery of tests of rodent behaviours such as grooming, eating, social interaction, ventral marking and foot-stomping. In a second experiment, a more detailed investigation was carried out of the effects of focal cortical lesions on ventral marking. The results of these experiments suggest that anterior cortical lesions in gerbils give rise to a number of different deficits in behaviour. The results further suggest that cingulate cortex is part of the neural substrate for ventral marking behaviour. The implications of these results for contemporary theories of frontal lobe function are discussed.

Ventral marking in the male Mongolian gerbil reflects present and future reproductive investments.

Ventral scent-marking in the male Mongolian gerbil, Meriones unguiculatus, may be related to reproductive potential. In four experiments involving nine groups, males' marking during 5-min. open field tests correlated with their social and reproductive status. The lowest levels of marking occurred among individually housed or subordinate males of a pair, followed by males exposed to ovariectomized females, and dominant males of a pair. Higher levels of marking occurred with vasectomized males living with intact females or following the removal of males from a nuclear family. The most frequent marking occurred when males were housed with pregnant females and with females and their offspring. The proximate stimuli leading to high marking appear to be the sexual availability of reproductively competent females.

Behavioural responses of the Indian gerbil,Tatera indica to conspecific sebum odour of the ventral scent marking gland

Behavioural responses of the Indian gerbil,Tatera indica, to conspecific sebum odour of the male ventral marking scent gland were studied in a glass cage and a plus maze. Male and female gerbils were attracted towards the strange male sebum odour though its magnitude was low in females possessing the ventral marking gland, still lower in the females in which the marking gland was absent. The diversity in preferential behaviour of femaleTatera indica is discussed in relation to the role of ventral marking behaviour in chemical communication among rodents. Correlating the results of the experiments with our field observations, it appears that the function of scent marking inT. indica is more of a ‘familiarisation’ nature to label the habitat for its own use in orientation or to signal ‘home’ to the marking animal.

Ventral marking in black and agouti gerbils ( Meriones unguiculatus)

Male and female Mongolian gerbils (Meriones unguiculatus) of both agouti and black coat color variations were tested for ventral marking in an open field. Males marked more than females and black gerbils marked more than the agouti animals. Black females marked at levels equal to those of agouti males, and thus they may be useful in future investigations of neural and hormonal factors affecting ventral marking in females. Such research was difficult in the past because of the extremely low levels of marking normally exhibited by agouti females.

The Behaviour of Mongolian Gerbils in a Semi-Natural Environment, With Special Reference To Ventral Marking, Dominance and Sociability

AbstractWe observed the behaviour of a colony of Mongolian gerbils (Meriones unguiculatlts) for 18 weeks, in an enclosure provided with facilities for burrowing, nest-building, foraging, wheel-running and other behaviour. Records were taken of both social and individual activities, and in particular of activities occurring during encounters between pairs of individuals. I. The colony originally consisted of eight animals, but severe fighting rapidly reduced the numbers to two males and two females. The colony then remained stable until week 18, when an adult male attacked the offspring of one of the females. Fighting was never observed between animals of opposite sex. The fighting was probably due to overcrowding, and suggests that in natural conditions gerbils do not nest in groups of more than a few adults. 2. Routine encounters between individuals revealed a number of sex differences, but few conspicuous individual differences. Agonistic behaviour was rare, and the observations gave little evidence for the existence of a dominance order. 3. When a female was in oestrus one male consistently attacked and chased the other, and consequently gained almost exclusive access to the female. The sequence of mating responses is described, and it is suggested that genital sniffing by the male enhances the receptivity of the female. Ventral marking by the female and drumming by the male occurred at unusually high levels during mating. 4. Each female produced two litters, but only the first two survived. The litters were dropped and the young housed in a nest-box outside the normal colony burrow, the entrance to which was kept blocked. Both litters were carried to another nest-box in the second week after parturition, and carried back again prior to the birth of the second litters, but the reasons for this behaviour were unclear. The males assisted in nest-building activities, but never entered the maternal nest-box. We suggest that the failure of the females to care for their second litters was due to overcrowding. 5. Ventral marking occurred at a high rate, and in conjunction with various activities. Marks were deposited over the entire enclosure and on a variety of substrates, but were concentrated at four main sites on mounds of earth near the burrow. There were no sex differences in total number of marks, but the males tended to distribute their marks more widely. Individual differences in amount of marking were correlated with differences in gland size, and with the outcome of aggressive encounters during mating and the occasional fighting. There was a strong tendency for fresh marks to elicit counter-marking by the same or another animal, but novel clean objects were also marked within a short time of being placed in the colony. There was no evidence that marked objects or areas were avoided by other animals or defended by the marker, and we suggest that marking is not primarily territorial in function. 6. Mutual marking, mutual grooming and sandbathing all occurred at the four most heavily marked sites near the burrow. We suggest that these activities, and the tendency for animals to counter-mark at specific sites, might serve to distribute a colony odour consisting of the odors of the individuals, and that this might reduce intra-colony aggression. We found no evidence that mutual marking or grooming reflected a dominance order. Drumming of the substrate occurred as an alarm response, but we saw no evidence of its use as an alarm signal. 7. The most frequent individual activity was digging. The burrow, which was inhabited by all the adults, consisted of from two to eight tunnels leading in towards a central nest of shredded paper, straw and leaves. The tunnels were repeatedly cleared and enlarged, and were often destroyed by digging at other locations. Freshly dug earth was often marked by the digger, and this seemed to elicit marking and digging by other animals. 8. Wheel running occurred only at a low rate, and did not develop a stereotyped character, but was performed by all animals. Contrary to expectations based on laboratory studies the majority of running occurred during the light phase of the cycle, and this was when the animals were most often active in the general sense. We suggest that gerbils are probably active day and night in natural conditions, and that the enhanced nocturnality shown in laboratory studies may be due to the lack of a dark burrow. 9. Other stereotyped activities such as shredding paper, gnawing and scrabbling were rare. 10. The results are summarized and discussed in relation to theories of dominance, ventral marking and sociability, and attention is drawn to the need for more field studies of behaviour in this species.

Septal lesions in meadow voles and Mongolian gerbils: Consummatory and investigatory behavior

In order to separate species specific from general effects of septal lesions on consummatory and investigatory behavior we chose to work with male Mongolian gerbils and meadow voles. These two rodent species are different in both the absolute amount of fluids consumed and reactivity to the palatability of the fluids presented in a single tube. Septal lesions did not elevate water consumption of either species. Septal lesioned gerbils tended to consume more sucrose, and septal voles clearly did drink more sucrose than their control counterparts. But only lesioned voles suppressed intake below control levels when presented with quinine. Exploratory behavior, which was measured only in gerbils, was also altered by septal lesions. Measurement of testosterone, seminal vesicles, and ventral marking glands (gerbils only) indicated that septal lesions alter hormonal systems in at least this species. The importance of comparative investigations in elucidating the general function of brain structures was discussed.

Effects of crowding and intermittent isolation on gerbils ( Meriones unguiculatus)

Gerbils were reared from weaning to adulthood in mixed-sex paired, crowded or isolate-crowded conditions, the latter consisting of placing crowded animals into individual boxes for 2 hr per day. Paired males exhibited more ventral marking and nonaggressive contact in social interaction tests; paired females were far more successful reproductively than either crowded group. Isolate-crowded males were more aggressive in the home cage and in social interaction tests, and isolate-crowded females were somewhat less successful reproductively than crowded females. The only anatomical or biochemical differences among groups were heavier testes in paired males and heavier body weights in crowded males. Reproductive failure and decreases in behavioral measures were not mediated by adrenal steroids. The isolate-crowded conditions aggravated the effects of crowding, rather than decreasing them.

Spontaneous neoplasms in aging Gerbillinae. A summary of forty-four neoplasms.

Forty-four neoplasms were found at necropsy in 115 gerbils from a colony of wild-caught, and first- or second-generation laboratory-raised gerbils. Ten species of gerbils varying from 24 to 61 months of age were affected. The neoplasms occurred in 18 primary locations and included nine neoplasms previously unreported in gerbils. Unusual neoplasms included several squamous cell carcinomas of middle ear, squamous cell carcinoma of ventral marking gland, and Hodgkin's-like lymphoma. Neoplasms were a significant cause of morbidity and mortality in these aging animals.

Gerbils reared by rats: Effects on adult open-field and ventral marking activity

At 72 hr after birth gerbil litters were divided and half the pups fostered to lactating mother rats whose own pups were removed. Remaining pups were returned to their natural mothers. Rat-reared gerbils weighed more at weaning than control gerbils but there was no weight difference at 100 days. When tested in the open-field as adults, rat-reared gerbils were found to locomote and to rear less than controls. The fostering treatment had no clear-cut effects on frequency of ventral marking, although there was a large sex difference for this measure. No sex differences in open-field activity were found.

A scent marking response associated with the ventral sebaceous gland of the Mongolian gerbil ( Meriones unguiculatus)

The Mongolian gerbil regularly marks objects in an open field by rubbing them with a midventral sebaceous scent gland. A method and apparatus useful for the study of this response are described. The marking and gland size are sexually dimorphic, with the male marking about twice as frequently as the female and possessing a gland roughly twice the size. Ventral marking in males is positively correlated with urination and defecation, and it is suggested that all three of these activities may in some situations be territorial scent marking responses.