Genetic analysis of cercarial emergence rhythms ofSchistosoma mansoni

Using two chronobiological variants ofSchistosoma mansoni (a blood fluke infecting man) from Guadeloupe (French West Indies), we carried out experimental crossbreeding between schistosomes with an early and those with a late cercarial shedding pattern. The results obtained on the F₁ (intermediate shedding patterns) and F₂ generations (early, intermediate, and late patterns) demonstrate that the cercarial emergence rhythms of schistosomes are genetically determined. This genetic variability is interpreted as a consequence of the selective pressure exerted by the two different hosts (man and rat) implicated in the life cycle ofS. mansoni from the Guadeloupean focus of schistosomiasis.This work received financial support from the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases and the CNRS.     

Development of feminine sexual behavior in the rat: Androgenic and temporal influences

The contributions of prenatal and postnatal androgen exposure upon the development of sexual behavior in rats were examined by prenatal treatment of pups with an androgen antagonist (flutamide) and postnatal androgenization or castration. Male and female rats were exposed to the androgen receptor-blocker flutamide (FLU) in utero via prenatal injections to the mother on Days 10 through 22 of gestation. At birth (Day 1) males were castrated. Both males and females were injected with either 100 μg testosterone propionate (TP) or oil on Day 1. In adulthood all gonadectomized animals were tested for the display of feminine sexual behavior (lordosis) in response to a range of estrogen dosages. Prenatal exposure to FLU enhanced lordosis in both sexes when compared to vehicle-treated controls. Postnatal TP treatment decreased lordotic potential as expected. However, in animals given TP postnatally, those receiving prenatal flutamide had higher lordosis quotients than animals receiving vehicle treatment. These data confirm (1) that the development of feminine sexual behavior is inhibited by androgen exposure, (2) that such exposure occurs prenatally, (3) that the potential for feminine behavioral differentiation occurs prenatally as well as postnatally, and (4) that androgen acts perinatally to affect estrogen sensitivity in adulthood.     

Influence of pinealectomy and photoperiod on courtship and nest-building in male doves

Sham-operated male doves displayed greater nesting activity under long days (16L:8D) than under short days (8L:16D). This difference was abolished by pinealectomy—the activity of long-day pinealectomized birds dropped to a level comparable to that seen on short days. Removal of the pineal had no effect under the short photoperiod. These results are not due to changes in peripheral androgen production as castrated, testosterone-implanted males also exhibited higher levels of nest-building on long days if sham-operated, but not if they were pinealectomized. Neither treatment had a significant effect on courtship or copulatory behavior. It is suggested that the pineal mediates the stimulatory effect of long photoperiods on hormonally-induced nest-building in doves.     

Age,experience, and rare-male mating advantages inDrosophila pseudoobscura

Because published experiments documenting frequency-dependent sexual selection have exclusively used young virgins, we endeavored to test for this same phenomenon in females who differed in age and in previous mating experiences. Direct observation tests were conducted employingDrosophila pseudoobscura females of the previously described Arrowhead (AR) and Chiricahua (CH) homokaryotypes. Four-day-old virgin females confer mating advantages on all tested rare males, i.e.,or. AR, and CH. Females who had a previous mating experience when younger award a rare-male advantage only when the rare male is of the same genotype of karyotype as their first mate, and matings are random when the first-mate type males are common. Equivalently aged (11 days) virgin females mate significantly more than expected with minority males if they are of the same karyotype as the females themselves. whereas matings are near random when the males are different. Frequency-dependent mating, therefore, is both age and experience dependent.A. P. is supported by funds from the Biopsychology Program, Hunter College and C.U.N.Y. L.F. is the recipient of USPHS Career Award 2KO3 HD 0903308: work supported by NIH Grant 5RO1 18907-02.Paper presented at the third annual meeting of the Behavior Genetics Association, Chapel Hill, North Carolina, April 7, 1973.     

Behavioral correlates of oral and postingestive satiety in the rat

Hungry rats display the characteristic "satiety sequence" after drinking a glucose solution: The end of ingestion is accompanied by grooming and exploring, followed by resting. With saccharin solutions over a range of concentrations, however, ingestion is accompanied and followed by persistent grooming and exploring; resting rarely occurs. Gastric preloads of glucose solution promote resting to reinstate the "satiety sequence" after a bout of saccharin ingestion. Therefore, the systemic effects of glucose are sufficient to promote resting. In the absence of postingestive factors, the "satiety sequence" is incomplete following saccharin ingestion as it is after sham-feeding.     

Comparison of gastric, duodenal and jejunal contributions to the inhibition of food intake in the rat

Rats equipped with tubes leading to their stomach, duodenum or jejunum were infused with a liquid diet for 9 hr (4 ml/hr) and were allowed to eat during the last 8 hr of infusion. All rats ate significantly less on diet infusion days than on saline or no infusion days. A second study showed that a taste aversion could not be conditioned to flavored water associated with diet infusion. Apparently, intrajejunal injection of nutrients produces satiety and not discomfort. Infusion of the diet for 5 consecutive days into the stomach, duodenum or jejunum consistently and significantly lowered food intake by reducing meal size, not meal frequency. Results suggest that the small intestine below the infusion site contributes to normal satiety.     

A microcomputer-based data acquisition system for continuous recording of feeding and drinking by rats

A monitoring system to continuously record the daily pattern of drinking and eating of rats is described. This system, based on a North Star microcomputer, can record the amount of food ingested with a temporal resolution of +/- 1.0 second and quantitative accuracy within +/- 5%. Drinking behavior is detected using a drinkometer which also has a temporal resolution of +/- 1.0 second. Data are analyzed by computer to determine absolute amounts of consumption and patterns of intake. The patterns of feeding and drinking recorded by this system are similar to those observed using other monitoring devices.     

Rat self administration of ethanol: Enhancement by darkness and exogenous melatonin

Using an FT 60 schedule, rats on 100% free feeding tested in the dark phase of a 12:12 light-dark cycle were trained to self-administer ethanol intravenously. The effect was dose-dependent with 20% ethanol being the preferred dose as measured by the number of infusions. Daily administration of 1.5 mg/kg melatonin significantly increased ethanol self-injection in the dark but not in the light. The time of day of testing and/or drug administration may be an important variable in studies on self-administration of drugs. Testing in the dark may eliminate the need for reducing body weight when inducing self-administration of ethanol.     

幼儿攻击性行为游戏矫正的倒返设计研究

目的：探讨幼儿集体游戏用于矫正幼儿攻击性行为的效果。方法：采用倒返实验，对三名被试进行了游戏矫正。结果：三名被试在实验的基线阶段有明显的攻击性行为，游戏介入后攻击性行为明显减少，游戏取消后攻击性行为再度增加，游戏再次介入后，攻击性行为再次明显减少；方差检验的结果表明，被试在基线阶段的攻击性行为与游戏矫正后的攻击性行为差异极显著。结论：运用自然的幼儿集体游戏可以矫正幼儿的攻击性行为。