Female Activity Levels Research Articles

老化と薬物の代謝 : 機能低下か雌化か.雄ラット肝の薬物代謝能の加齢変動

The profiles of hepatic drug metabolism were obtained by using young and old male and female rats. The profile obtained from old male rats was completely different from that from young male rats, while it was almost identical to those of females of any ages. This was due to the selective decrease in male hepatic enzyme activities showing higher activities than females to the activity levels of females which did not alter much with aging. Castration of young adult male rats caused a decrease in enzyme activities but did not result in the feminization of the metabolic profile. Administration of testosterone to old male rats resulted in the recovery of the profile of young male rats, but the levels of activities were not as high as young male rats. Plasma testosterone levels were found to decrease in parallel with drug metabolizing activities of male rats during aging. These results suggest that sex hormones play important roles in the alteration of drug metabolizing activities in male rats with aging. The loss of male characteristics in profile of drug metabolism during aging was evaluated by use of antibody to the male specific cytochrome P-450, P-450 m1. Anti-P-450 ml strongly inhibited imipramine N-demethylase activity, which showed marked sex (male greater than female) and age (young greater than old) differences, while this did not inhibit imipramine 2-hydroxylase activity, which showed no sex or age differences. The portion of N-demethylase activity inhibited by this antibody decreased in old rats while the portion not inhibited did not decrease with age. These results indicate that the decrease of sex specific cytochrome P-450 is responsible for the age-associated decrease in at least one of the drug metabolizing enzyme activities in male rats. It is suggested that some processes of the control mechanism of the gene expression of male specific cytochrome P-450 may be altered with old age.

Thermoregulation and Activity Patterns of the Sand Wasp Steniolia longirostra (Say) (Hymenoptera: Sphecidae) in Costa Rica

In the neotropical sand wasp Steniolia longirostr-a (Say), female activity levels in the nesting area were negatively correlated to ambient temperature and positively correlated to relative air humidity. The wasps showed high activity below 350C and above 40 percent relative humidity. Females with a low wing load had a lower body temperature during flight compared to females with a high wing load. This may offer females with favorable body proportions benefits, as they can enjoy longer daily provisioning periods. MICROCLIMATE HAS A SUBSTANTIAL EFFECT on the behavior of most insect species. Maintenance of an adequate body temperature and water balance is difficult for small animals, whether using ectothermic (behavioral) or endothermic (physiological) mechanisms for its regulation (May 1985). Numerous studies of thermoregulation in Hymenoptera have been carried out in recent years. However, as in other insect groups, most research has been conducted on temperate zone species (but see May & Casey 1983, Vogt & Heinrich 1987). Sand or digger wasps occupy dry and sunny habitats in temperate and tropical areas. Many species dig their burrows in the ground, exposing themselves to extreme shifts in ambient temperature during surface activities (Nielsen 1945). The few studies published on their thermoregulation suggest that they are ectothermic, that is, regulate their body temperature by behavioral means (Willmer 1985a, O'Neill & O'Neill 1988). One should suspect intraspecific variation in body size of ground-nesting tropical wasps to be related to their thermoand hygroregulatory capacity (as for temperate species, see Wilmer 1985 a). As a consequence, I hypothesized differences in activity patterns between differently sized nesting females. I present here some data on the activity and thermoregulation of a gregarious neotropical sand wasp, Steniolia longirostra (Say) (Hymenoptera: Sphecidae: Nyssoninae), during the hot and dry season in Costa Rica. This genus embraces about fifteen species, ranging from southwestern Canada to Central America. S. longirostra has been recorded from late September through May, mainly from southern Mexico. The females of this medium-sized wasp are characterized by their fast, hovering flight. They dig burrows in dry, sandy ground, where they provision their larvae with flies (Evans & Gillaspy 1964, Gillaspy 1964).

Time budgets and behavioural synchronization in aggregated and isolated male and female mice

Albino mice ( Mus musculus ), initially housed in single sex groups and, subsequently, in social isolation, were used in this study to analyze the influence of social companions on the amount and on the distribution throughout the day of several behaviours. An observational recording technique was employed to record behaviour during the dark phase of the day. Behavioural sex differences in grouped mice were observed in four out of six behavioural categories. Females generally proved to be more active than males. Furthermore, prolonged social housing conditions resulted in an increase in male social interactions, in concomitance with changes in their time budgets. Conversely, females showed a decrease over time in social interactions with only slight effects on their time budget. Isolation seemed to increase slightly both male and female activity levels. Subjects housed together generally showed significantly similar Rest, Feed and General Activity patterns throughout the dark phase of the day. By contrast, the averaged patterns of different groups generally proved to be dissimilar in grouped females, but not in grouped males. When isolated, mice showed a distribution of their activities throughout the day different from what they had displayed under social conditions. These data indicate that social environment has an effect on the individual activity profiles which results in a definite synchronization within female groups and in a tendency towards desynchronization within male groups.

The hormonal regulation of hepatic microsomal 11beta-hydroxysteroid dehydrogenase activity in the rat.

Hepatic microsomal 11beta-hydroxysteroid dehydrogenase activity is higher in male than in female rat liver. Gonadectomy on day 25 of life only affects the activity in the adult male animal, causing a decrease towards the normal female level. Administration of testosterone to gonadectomized rats of either sex causes the induction of typical male activity levels. On the basis of these experiments, this enzyme activity may be classified as an drogen-dependent. However, 11beta-hydroxysteroid dehydrogenase differs from other known androgen-dependent activities in that administration of oestradiol to gonadectomized animals of either sex causes a further significant repression of the activity to levels close to the limits of detection. Hypophysectomy on day 50 of life does not affect the activity in 75 day-old male rats, but causes the appearance of typically male activity levels in females. These results indicate that the hypophysis exerts a repressive influence on hepatic 11beta-hydroxysteroid dehydrogenase in female rats. The facts that this activity is not influenced by androgen or oestrogen administration once the pituitary has been removed demonstrates the obligatory role of the hypophysis for sex hormone action.

A Note on Economic Activity of Women in Nigeria

The aim of this article is to investigate some of the factors explaining the economic activity of women in Nigeria, in particular, to examine the question of whether urbanisation is likely to lead to a "marginalisation" of Women in Nigeria. Such a question would not normally be asked in most developing countries because, since recorded female labour force participation is low in the rural areas of most countries, it could be expected that urbanisation would be associated with rising levels of female activity. However, a different situation exists in sub-Saharan Africa with female participation in the rural economy being strikingly high.1 This is associated with a traditional division of labour which allocates prominent roles to women in subsistence agriculture and often in trading activities. This tradition is partly explained by the need for men to travel long distances to hunt or, in this century, increasingly to find wage earning activity. The present study is based on a survey carried out by the Human Resources Research Unit of the University of Lagos in 1973 and 1974. It covered a sample of 2,700 women aged 20 and over drawn from four areas of Nigeria. It is admitted at the very outset that conceptual deficiencies in the survey appear to have led to an understatement of labour force participation in rural areas, making the analysis somewhat questionable.

Oxygen consumption in the prosobranch snail Viviparus contectoides (Mollusca: Gastropoda)—I. Effects of weight and activity

1. 1. Metabolic rate (cm 3 O 2/hr and log cm 3 O 2/hr) of Viviparus contectoides is dependent on weight and log weight at levels of minimum and intermediate activity in males and minimum activity in females. 2. 2. Weight specific oxygen consumption and log weight specific oxygen consumption of V. contectoides is dependent on weight and log weight at levels of intermediate and maximum activity in males and at all activity levels in females. 3. 3. Respiration coefficients are affected by activity level or time of day. They decrease significantly with increasing activity level in males. Respiration coefficients are generally lower than literature values. 4. 4. The relationship of oxygen consumption to weight is similar for males and females at each level of activity. 5. 5. Mean absolute oxygen consumption (cm 3/hr) is greater for females than males at each activity level. Mean weight of females is greater than mean weight of males.