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PubMed2005

Population structure and dynamics of Gammarus fossarum (Amphipoda) upstream and downstream from effluents of sewage treatment plants.

Two streams in Germany (Körsch and Lockwitzbach), each with two sampling sites above and below a sewage treatment plant (STP) discharging effluent, were investigated. Sampling sites were characterized, and exposure monitoring for chemicals with known or assumed endocrine disrupting potential was carried out. Both the population structure and the population dynamics of Gammarus fossarum were examined. The physicochemical parameters measured at the sampling sites of the Lockwitzbach and Körsch streams were found not to reach levels having an acute toxic impact on the development of gammarids. The calculated estrogenic potential in the stream water was 22- to 35-fold higher at the downstream site of the Körsch compared with the other sampling sites, mainly because of the concentrations of 17alpha-ethinylestradiol on two sampling dates. At both streams, an influence of the respective STP effluent on the sex ratio of G. fossarum was not observed. Moreover, intersexuality was not induced by these effluents. Differences in the structure and dynamics of G. fossarum populations were more pronounced at the Körsch than at the Lockwitzbach. At the downstream sampling site at the Körsch, gammarids reached their highest abundances. Particularly at the downstream sampling site of the Körsch, the proportion of breeding female gammarids and the proportion of juvenile gammarids in the smallest body length class were decreased compared with upstream. Adult gammarids were larger from the Lockwitzbach downstream site, but they were smaller from the Körsch downstream site compared with the respective upstream site. At the Körsch, the earlier onset of the autumnal reproductive resting period could be caused by the influence of the STP effluent.

Acanthocephala↗
PubMed1999

No evidence for congenital malformations or prenatal death in infants born to women with a high dietary intake of fish contaminated with persistent organochlorines.

OBJECTIVES: The aim of the present study was to assess whether a high dietary intake of fatty fish from the Baltic Sea, contaminated with persistent organochlorine compounds, might increase the risk for congenital malformations and perinatal death. METHODS: A cohort of fishermen's wives from the Swedish east coast (at the Baltic Sea) were linked to the Swedish Medical Birth Register (MBR), resulting in the identification of 1501 infants born in the period 1973-1991. A further linkage with the Swedish Registry of Congenital Malformations was performed. Similar linkages were made for a comparison group of fishermen's wives from the Swedish west coast, who gave birth to 3553 infants during the study period. The reproductive end points studied included congenital malformations, stillbirths, and early neonatal deaths. The expected numbers of these end points were calculated from the MBR data for the regional populations. RESULTS: In the east coast cohort, 3.3% of the infants had some malformation diagnosis as compared with 5.0% of the west coast cohort. As compared with the general population, somewhat fewer malformations than expected were diagnosed in the east coast cohort (risk ratio 0.78, 95% CI 0.58-1.04). No specific malformation was overrepresented in the east coast cohort. The risk ratios for stillbirths and early neonatal deaths did not significantly differ from unity in any of the cohorts. CONCLUSIONS: The present results exclude in an unequivocal way an association between exposure to persistent organochlorines from fatty Baltic Sea fish and an increased risk for all congenital malformations and perinatal death. The limited power of the study design, however, does not allow the exclusion of slight risk excesses for some specific types of malformation.

Adolescent↗
PubMed1991

Contraceptive prevalence, reproductive health and our common future.

The 1980s will go into history as a decade of lost opportunities to increase contraceptive prevalence and improve reproductive health worldwide. As the decade closes, 500 million couples still have no access to fertility regulation, there are 30-50 million induced abortions each year, 15 million infant and child deaths (30% of all deaths worldwide), an estimated 250 million new cases of sexually transmitted diseases and 60-80 million infertile couples. One of the major problems is that many policy makers are still unimpressed with the global demographic reality. World population was less than 300 million 1991 years ago. It took some 1500 years to double this number by the time of the voyages of Columbus to America. The first billion was reached at the beginning of the last century and the second in the lifetime of the author, in 1927. Then it took less than 50 years to double this number to 4 billion by 1976. Global population is 5.3 billion today. In view of such figures, it is understandable that, historically, it was this demographic concern that in the 1960s persuaded many governments to support family planning programmes. During the subsequent decades, it was gradually recognized by developing country governments that family planning lowers infant, child and maternal mortality and morbidity and reduces the number of illegal abortions and their health hazards. Today, 52 developing country governments support family planning programmes for the demographic rationale, but 65 for the reproductive health and human rights rationale. Where do we go from here? That will mainly depend on the number of years it will take to reach replacement level of fertility (around 2.1 children per couple) worldwide. If the level is reached in 2010 (the low projection of the United Nations), global population will stabilize by the end of the 21st century at 8 billion; if it is reached in 2035 (medium projection), population will stabilize around 10 billion; however, if it is reached only in 2065 (high projection), the global population in 2100 will consist of more than 14 billion people, with major consequences on every walk of life. To restrict the final population to 10 billion, contraceptive prevalence must increase from 51% to 58% of married women of reproductive age before the year 2000 and to 71% by 2020, implying an increase from the present 350 million users to 500 and 800 million, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Contraception↗
PubMed1985

Absence of gonadal-hormone feedback on luteinizing hormone in both photorefractory and photosensitive white-crowned sparrows (Zonotrichia leucophrys gambelii).

Elimination of gonadal-hormone feedback by castration from photorefractory male White-crowned sparrows in mid-July or early October, and from photosensitive males in early December, had no significant effect on plasma levels of LH. Photorefractory birds held on natural daylengths regained photosensitivity in the absence of gonadal-hormone feedback with no increase in plasma levels of LH. Implants of testosterone propionate into castrated males during November and December had no effect on plasma LH levels. These results indicate that gonadal-hormone feedback is not responsible for the very low levels of LH secretion in either the photorefractory or the photosensitive male White-crowned sparrow.

Animals↗
PubMed1987

Annual cycles in plasma testosterone and thyroxine in the male aspic viper Vipera aspis L., (Reptilia, Viperidae), in relation to the sexual cycle and hibernation.

Blood samples were taken monthly from males of Vipera aspis kept in outdoor terraria. Plasma testosterone was estimated by radioimmunoassay and plasma thyroxine by the technique of isotopic competition, between October 1979 and September 1985. Plasma testosterone showed an annual bimodal profile. The highest peak was observed from February 15 to the end of March. 2 to 5 weeks after the first emergence from hibernation. Values then decreased greatly, to reach a minimum level when the vernal spermiogenesis was at its maximum. The secondary peak of plasma testosterone was lower and less well marked. It occurred at the end of summer, during the strongest spermiogenesis, and preceded the autumnal facultative mating period. Plasma thyroxine was at a maximum concentration from February to March after which levels decreased markedly. The seasonal profile of plasma thyroxine was clearly marked during the period of hibernation. From September to October, 2 months before the beginning of hibernation, thyroxine levels began to decrease, and they reached a minimum in November-December. Endocrine reactivation of the thyroid appeared at the end of hibernation. However, in contrast to the plasma testosterone, endocrine activity of the thyroid began 2 to 3 weeks before the end of hibernation. Mechanisms of reactivation for testicular and thyroidal endocrine structures are discussed.

Animals↗
PubMed1987

Semilunar changes in estradiol and cortisol coincident with gonadal maturation and spawning in the killifish Fundulus heteroclitus.

Radioimmunoassay techniques were used to measure estradiol-17 beta (E2) and cortisol in the serum and ovarian fluid of Fundulus heteroclitus throughout complete semilunar spawning cycles. The cyclic nature of spawning activity was confirmed by monitoring the gonadosomatic index and noting the times at which ovulated eggs were found within the ovarian lumen. Levels of serum E2, ovarian fluid E2, and serum cortisol all exhibited cycles which paralleled the semilunar cycle of gonadal maturity and spawning in this euryhaline killifish. Elevations of serum cortisol were temporally associated with ovulation, whereas ovarian fluid E2 levels peaked several days prior to ovulation. Serum E2 remained elevated after ovarian fluid E2 levels had returned to baseline. Cortisol concentrations in ovarian fluid did not cycle and no correlation was apparent between serum cortisol and glucose concentrations.

Animals↗
PubMed1988

Thyroidectomy and the termination of juvenile refractoriness in the red-legged partridge (Alectoris graeca chukar).

The role of thyroid hormones in the maintenance of juvenile refractoriness was studied in the red-legged partridge hybrid, Alectoris graeca chukar. Juvenile partridges, maintained on long (20L:4D) daylengths from hatch, were radiothyroidectomized at 6 1/2 weeks of age, and after 2 weeks were either held on long days or transferred to short (8L:16D) daylengths. Short-day thyroidectomized birds showed no evidence of gonadal growth 18 weeks after thyroidectomy, and neither did euthyroid controls on either short or long daylengths. Thyroidectomized birds held on long daylengths did show significant gonadal growth at this point. Further treatment with low levels of thyroxine (10 micrograms/bird) led to even greater testicular development in long-day thyroidectomized birds, but had no effect on the gonads of short-day thyroidectomized or euthyroid birds.

Aging↗
PubMed1990

Relationships among hormonal changes, cuticular hydrocarbons, and attractiveness during the first gonadotropic cycle of the female Calliphora vomitoria (Diptera).

Attractiveness in adult females of Calliphora vomitoria is correlated with ovarian development and there is a marked increase during the previtellogenic and vitellogenic periods. The development of attractiveness may result from the combined actions of ecdysteroids and juvenile hormone. A rise in total hydrocarbons parallels the first increase in levels of these hormones during the previtellogenic stage. Cuticular hydrocarbons subsequently fall, along with the disappearance of hemolymphatic ecdysteroids, and then rise again during the vitellogenic phase of JH production. Increasing and decreasing of some cuticular hydrocarbons, some hydrocarbons implicated in the attractiveness, are correlated with variation of the titer of these hormones, especially JH III.

Animals↗
PubMed1980

Ultrastructural observation of oogenesis in the crustacea amphipoda Orchestia gammarellus (Pallas).

The oogenesis of the Crustacea Amphipoda Orchestia gammarellus can be divided in five stages taking into consideration both the oocyte ultrastructure and the physiology of the ovary. The primary oogonium (12 micron in diameter) is lodged within the germinative zone: after division, the daughter cell (or secondary oogonium) leaves this area and enters meiotic prophase. Stage I is represented by the oocyte with visible chromosomes (12-18 micron in diameter) the cytoplasmic ultrastructure of which is comparable to that of the oogonium. Stage II or previtellogenesis is characterized by a considerable growth of the oocyte (18-80 micron in diameter) which becomes enriched in ribosomes and vesicles of the rough endoplasmic reticulum; the oocyte does not yet contain any vitelline reserve (proteinaceous and lipid). Stage III or primary vitellogenesis (80-160 micron in diameter) is typified by the synthetic activity of the rough endoplasmic reticulum, corresponding to an endogenous accumulation of proteinaceous yolk. Stage IV or secondary vitellogenesis (160-800 micron in diameter) only appears during the period of reproduction; by means of endocytosis the oocyte accumulates yolk spheres in addition to lipid droplets, the origin of which is uncertain; towards the end of vitellogenesis, cortical granules become a feature that is noted for the first time in Crustacea. The last stage or maturation (800 micron in diameter) starts right before or immediately after the exuviation of the female and ends with fertilization.

Animals↗