Early experience, mammals

In mammals, early experience with social odors will have lasting effects on odor preferences. We have to distinguishji/w/ (attachment ofyoung... 

Long-lasting and specific effects of early odor experience have not yet been reported for many mammal species. In one experiment, rat mothers that raised male pups had their nipples and vagina scented with citral. When tested at 100 days of age, these males ejaculated sooner with sexually receptive, citral-scented females than with controls. Conversely, the latency to ejaculation of males reared with saline-treated mothers was shorter in matings with normal females than with citral-scented ones (Pillion and Blass, 1986). 

From a thermochemical viewpoint, can a human or animal be regarded as just a catalyst for the combustion of foodstuffs To answer this question, large calorimeters were constructed into which an animal or a human being was placed. If, while in the calorimeter, the subject neither gained nor lost weight, the heat evolved should have been just equal to - AH for combustion of the food consumed to C02, water, and urea. That this prediction was verifed experimentally does not seem surprising, but at the time that the experiments were first done in the early years of the century there may have been those who doubted that the first law of thermodynamics applied to mammals. 

Lilly s studies of the human brain sparked his interest in the brains of other intelligent mammals, dolphins in particular. Lilly performed two long stretches of experiments in dolphin intelligence and human-dolphin communication, one series in the 60s and a second in the early 80s. These efforts bore fruit in ideas that were published in several books, notably Man and Dolphin, and that many believe to have influenced favorably the passage of the landmark Marine Mammal Protection Act. 

No enzyme system which will oxidize kynurenine to hydroxykyiiurenitie has yet been isolated in a cell-free state from any species, and there is some evidence that direct conversion may not normally occur, at least in mammals. Riboflavin was suggested to be concerned in hydroxykynurenine formation at a comparatively early stage (387), and this has been supported by nutritional experiments. 

On the other hand, it was perhaps fortunate that at this early stage of interest in olfactory communication of mammals those involved were not aware of all these problems otherwise, the enthusiasm of many of them would surely have been dampened. Incidentally, the belief that the responses of mammals to odour signals are stereotyped and genetically controlled prevailed for a long time. This oversimplification, even today, often confuses many workers without previous experience in behavioural studies. 

When large, multicellular organisms developed, vith specialized organs, some of these abilities became a handicap, and were lost. Let us continue with thiamine as an example. All mammals require thiamine in their food, in order to live. The ability to synthesize thiamine was lost by an early ancestral vertebrate, several hundred million or a billion years ago. This animal was ingesting plants, which provided an ample supply of thiamine, about 5 mg for each 2500 kcal of food energy. The sjmthetic mechanism was not needed, and it was a burden it cluttered up the cells, added to the body weight, used energy that could be better used for other purposes. When a series of mutations occurred that eliminated this mechanism, the mutant was favored over the wild type, which failed to meet the competition and died out. The victory of a mutant strain of a bacterium over the wild type in the competition for survival in the presence of an ample supply of the essential nutrient has been verified by direct experiments in the laboratory by Zamenhof and Eichhorn. ... 

It was postulated by Lyon that one or the other X chromosome in somatic cells of female mammals is at some early embryonic stage rendered inactive. The inactivated X chromosome, which may be of paternal or maternal origin, will remain inactive in all progeny of the embryonic cells. The major evidences cited by Lyon for this hypothesis were the occurrence of mottled or dappled coat colour phenotypes in heterozygous female mice and the existence of normal XO females. As a consequence of random inactivation of X chromosomes, females heterozygous for X linked traits exhibit mosaic phenotypes. Evidence in support of the hypothesis has been gathered in a variety of experiments. 

These strategies are not fixed and can be influenced by the experiences of the fish, for example transportation (Ruiz-Gomezerai, 2008).In mammals and birds early life experiences or even the experiences of the parents can also influence the nature of the offspring through epigenetic mechanisms (e.g. Weinstock, 1997 Gluckman et /., 2007 Rutherford et a/., 2009). In fish maternal condition does have various effects on offspring (e.g. Schreck et al., 2001 Tierney et al., 2009) however, the few studies that have examined such effects in fish have found no effect on susceptibility to infectious disease (Contreras-Sanchez et al, 1998). 

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