Serum persistent organic pollutants and diminished ovarian reserve: a single-exposure and mixture exposure approach from a French case-control study

STUDY QUESTION

Are persistent organic pollutants (POPs) associated with a diminished ovarian reserve (DOR) in women of reproductive age?

SUMMARY ANSWER

Amongst 17 POPs detected in over 20% of serum samples, only p,p'-DDE was significantly associated with an increased risk of DOR, and β-hexachlorocyclohexane (β-HCH) was significantly associated with a decreased risk of DOR whilst mixture analyses yielded non-significant associations and did not detect any interactions between POPs.

WHAT IS KNOWN ALREADY

Animal studies have shown that several POPs can alter folliculogenesis and increase follicle depletion. However, only a few studies have been conducted in humans, with small sample sizes and inconsistent results.

STUDY DESIGN, SIZE, DURATION

Our study included 138 cases and 151 controls from the AROPE case-control study. Study participants were women between 18 and 40 years of age recruited amongst couples consulting for infertility in four fertility centres in western France between 2016 and 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cases of DOR were defined as women with anti-Müllerian hormone (AMH) levels ≤1.1 ng/ml and/or antral follicle count (AFC) <7, and controls were women with AMH levels between 1.1 and 5 ng/ml and AFC ≥ 7, without genital malformations and with a menstrual cycle length between 26 and 35 days. A total of 43 POPs (including 15 organochlorine pesticides, 17 polychlorinated biphenyls, and 9 polybromodiphenylethers) were measured in the serum at inclusion into the study. We conducted logistic regression adjusted for potential confounders using a directed acyclic graph to study the effect of each POP on DOR as single exposures, and used Bayesian kernel machine regression (BKMR) to measure the mixture effect of POPs on DOR.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 43 POPs, 17 were detected in over 20% of the serum samples. In the single-exposure multivariate logistic regressions, p,p'-DDE (median 165.0 IQR 161.0 ng/l in controls) as a continuous exposure was significantly associated with an increased risk of DOR (odds ratio (OR) 1.39, 95% CI 1.10-1.77) and non-significantly associated with an increased risk of DOR for the second and third terciles (OR 1.46, 95% CI 0.74-2.87, and OR 1.72, 95% CI 0.88-3.37, respectively). β-HCH (median 24.2 IQR 21.5 ng/l in controls) was significantly associated with a decreased risk of DOR when β-HCH was treated as a continuous exposure (OR 0.63, 95% CI 0.44-0.89) and for the third tercile of exposure (OR 0.43, 95% CI 0.21-0.84) and non-significantly associated with a decreased risk of DOR for the second tercile (OR 0.77, 95% CI 0.42-1.42). All sensitivity analyses confirmed our results. BKMR showed similar associations for single exposures but found no significant associations for the total mixture effect. In addition, the BKMR results did not suggest any interactions between POPs.

LIMITATIONS, REASONS FOR CAUTION

Controls were recruited amongst infertile couples and thus may not be representative of all women of reproductive age. However, their POP concentrations were in the same range as in the general French population.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the first to examine the associations between serum POPs and DOR. The well-recognized anti-androgenic properties of p,p'-DDE and estrogenic properties of β-HCH could explain these associations of opposite direction. If these results are replicated elsewhere, this could have an impact on fertility prevention messages and help in understanding the impact of POPs on the female reproductive system.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Fondation de France (grant numbers 2014-50537 and 00110196) and the French Biomedicine Agency (2016). None of the authors have any conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Infant neurodevelopment and behavior in Guadeloupe after lead exposure and Zika maternal infection during pregnancy

BACKGROUND

Prenatal lead exposure is known to have neurotoxic effects on the developing fetus, while some viral infections may have a tropism for the central nervous system. Our objective was to study whether the effects of prenatal lead exposure on infant development and behaviors at 18 months of age are modified by the occurrence of a maternal infection to Zika virus (ZIKV) during pregnancy.

METHODS

During the ZIKV epidemic in Guadeloupe in 2016 a cohort of pregnant women was set up. Blood samples (pregnancy, childbirth and cord) (n = 297) enabled us to measure blood lead levels aimed to determine prenatal lead exposure and the likelihood of maternal infection during pregnancy (ZIKV status + vs -). The 18 months "Ages and Stages Questionnaire" (ASQ) was used to generate scores for global development, fine and gross motor skills, communication, problem solving, and personal-social skills. The questions from a longitudinal cohort study conducted in Canada (Québec) were used to generate hyperactivity, opposition, inattention and physical aggression scores. Associations were tested by multivariate linear regressions.

RESULTS

Prenatal lead exposure was associated with delays in neurodevelopment at 18 months, reflected by lower scores in ASQ totals, and in the fine motor and problem-solving domains. Some of these associations appeared to be sex-specific, observed almost exclusively in boys (ASQ total, fine motor and personal-social scores). Prenatal lead exposure was not associated with behavioral scores. ZIKV infection during pregnancy was associated with a lower fine motor ASQ score, and higher scores for hyperactivity, opposition and physical aggression. Significant interaction between prenatal lead exposure and ZIKV status was observed with a lower personal-social score in ZIKV (-) only, and for hyperactivity and inattention scores, though some of these interactions (ASQ personal-social score, inattention score) were no longer significant when children with microcephaly were excluded from the analyses.

DISCUSSION/CONCLUSION

Our study confirms previous findings of associations between prenatal exposure to lead at low levels and adverse neurodevelopmental outcomes during infancy and the particular vulnerability of boys. It suggests associations between ZIKV infection during pregnancy and adverse effects on a number of neurodevelopmental functions (fine motor function) and behaviors (opposition, hyperactivity), that need to be confirmed at later age. There is no strong evidence of interaction between ZIKV infection and lead exposure but both prenatal risk factors may affect fine motor function.

Simultaneous exposure to both Zika virus and household insecticides during pregnancy, and fetal growth and infant developmental behavior outcomes at 18 months, in Guadeloupe

BACKGROUND

Perinatal infection with Zika virus (ZIKV) could result in adverse growth, developmental and behavioral outcomes, while insecticides used to control mosquitoes are neurotoxic.

OBJECTIVES

We aim to study the role played by exposure during pregnancy to both ZIKV and household insecticides in newborn health, development and behavior at age of 18 months.

METHODS

Maternal and cord blood samples from a cohort of pregnant women (created during Guadeloupe's Zika epidemic of 2016) were used to identify ZIKV infection during pregnancy. A self-administered questionnaire at birth documented prenatal household use of insecticides. Birth weight and head circumference were collected from maternity records (n = 708). Infant development and behaviors were documented at 18 months of age through the Ages and Stages Questionnaire and the Quebec Longitudinal Study of Child Development (n = 409). Logistic and linear regression models were performed, taking into account confounding factors.

RESULTS

Use of household insecticides was associated with smaller head circumference and lower birth weight among newborns from mothers not exposed to ZIKV: 0.3 cm (95% CI: 0.6, 0) and -82 g (95% CI: 165, 0), respectively. Similar decreases were observed with ZIKV exposure among mothers not reporting household insecticides use, and with presence of both exposures. The combined presence of ZIKV exposure and insecticide use was associated with lower ASQ fine motor scores (-3.9; 95% CI: 7.3, -0.4), and higher hyperactivity scores (0.8; 95% CI: 0.0, 1.5), compared to no exposure to either. A higher opposition score was observed in association with ZIKV exposure among non-users of insecticide (0.6; 95% CI: 0.0, 1.2).

CONCLUSION

Adverse neurodevelopmental outcomes at 18 months of age were observed with prenatal ZIKV exposure, and with higher magnitude when mothers reported use of household insecticides. At birth, rates of adverse fetal growth were however similar for the combined presence of exposure and either of the exposures.

Pre- and post-natal exposure of children to organophosphate flame retardants: A nationwide survey in France

The use of organophosphate flame retardants (OPFRs) has been on the rise ever since many brominated flame retardants were banned, back in the 2000 s. The objectives of this study are to describe the pre- and post-natal exposure of children to OPFRs, and to explore their possible determinants. A total of 259 children aged 3.5 years and 388 mothers from the French ELFE mother-child cohort were included. Both pre- and post-natal exposure to OPFRs were assessed, using OPFR concentrations in the hair of pregnant women (in 2011) and their 3.5-year-old children (in 2014-2015) for 15 OPFRs, of which 9 were detected in > 20 % hair samples. The highest geometric means for pre-natal exposure were 272 ng/g for tris(1-chloro-2-propyl) phosphate (TCPP), 69.7 ng/g for ng/g for triphenyl phosphate (TPP) and 54.4 ng/g for tris(1,3-dichloro-2-propyl) phosphate (TDCPP). The highest geometric means for post-natal exposure were 249.6 ng/g for TCPP, 85.3 ng/g for TDCPP and 83.8 ng/g for 2-ethylhexyl diphenyl phosphate (EHDPP). Correlations were found between both pre-natal exposures, and between pre-and post-natal exposures. No correlation was however found between pre-and post-natal exposures for any given OPFR. Pre-natal exposure to the 9 OPFRs was associated with pre-natal exposure to polybrominated diphenyl ethers 209 (BDE209), and 47 (BDE47). Maternal BMI was associated with pre-natal exposure to OPFRs other than TBEP. Home renovation work prior to birth was also associated with pre-natal exposure to OPFRs, with the exception of EHDPP, tris(2-butoxyethyl) phosphate (TBEP) and triethyl phosphate (TEP). Determinants of post-natal exposure appeared more disparate across OPFRs; although both the type of flooring in children's rooms and pre-natal exposure to polybrominated diphenyl ethers seem to be associated with post-natal exposure. Lastly, higher socioeconomic status appeared to be associated with lower exposure for several (though not all) OPFRs. The high prevalence of exposure to OPFRs suggests the need for studies to assess the health effects of OPFRs exposure, particularly on children.

Exposure of pregnant women to organophosphate insecticides and child motor inhibition at the age of 10-12 years evaluated by fMRI

BACKGROUND

Organophosphate pesticides (OP) are widely used for both agricultural and domestic purposes. Epidemiological studies suggest neurotoxicity in children after exposure to organophosphates pesticides (OP) at low levels but possible mechanism is still unclear.

OBJECTIVES

We aimed at investigating the effects of prenatal exposure to OPs on inhibitory control of 10-12 year-old-children assessed by a motor inhibition task during functional magnetic resonance imaging (fMRI).

METHODS

Ninety-five children from the PELAGIE cohort (Brittany-France, from 2002) underwent a fMRI examination during which inhibition was assessed by a Go/No-Go task. Task performance was assessed by average response latency, commission rate and composite performance score (PS). Whole brain activation was estimated by modeling the hemodynamic response related to inhibition demand and successful inhibition. OP exposure was assessed by measuring six dialkylphosphate (DAP) metabolites in the urine of women in early pregnancy (<19 WG). Concentrations were summed to obtain overall levels of diethylphosphate (DE), dimethylphosphate (DM) and total non-specific metabolites (DAP), standardized to homogenize sampling conditions and categorized into levels of exposure: low (reference), moderate or high. Regression models were adjusted for potential cofounders considered by restriction and statistical criteria.

RESULTS

Moderate levels of DAP were associated with a decreased commission rate (β = -6.65%, p = 0.04), indicating improved performance. Increasing levels of DM and DE were associated with decreased brain activity in the left inferior and bilateral superior frontal regions during successful inhibition. We did not observe any differential activation related to inhibitory demands.

DISCUSSION

These results suggest that prenatal OPs may be associated with altered pattern of brain activity in regions related to inhibition among children and need to be confirmed by additional studies.

Impact of maternal body mass index and gestational weight gain on pregnancy complications: an individual participant data meta-analysis of European, North American and Australian cohorts

OBJECTIVE

To assess the separate and combined associations of maternal pre-pregnancy body mass index (BMI) and gestational weight gain with the risks of pregnancy complications and their population impact.

DESIGN

Individual participant data meta-analysis of 39 cohorts.

SETTING

Europe, North America, and Oceania.

POPULATION

265 270 births.

METHODS

Information on maternal pre-pregnancy BMI, gestational weight gain, and pregnancy complications was obtained. Multilevel binary logistic regression models were used.

MAIN OUTCOME MEASURES

Gestational hypertension, pre-eclampsia, gestational diabetes, preterm birth, small and large for gestational age at birth.

RESULTS

Higher maternal pre-pregnancy BMI and gestational weight gain were, across their full ranges, associated with higher risks of gestational hypertensive disorders, gestational diabetes, and large for gestational age at birth. Preterm birth risk was higher at lower and higher BMI and weight gain. Compared with normal weight mothers with medium gestational weight gain, obese mothers with high gestational weight gain had the highest risk of any pregnancy complication (odds ratio 2.51, 95% CI 2.31- 2.74). We estimated that 23.9% of any pregnancy complication was attributable to maternal overweight/obesity and 31.6% of large for gestational age infants was attributable to excessive gestational weight gain.

CONCLUSIONS

Maternal pre-pregnancy BMI and gestational weight gain are, across their full ranges, associated with risks of pregnancy complications. Obese mothers with high gestational weight gain are at the highest risk of pregnancy complications. Promoting a healthy pre-pregnancy BMI and gestational weight gain may reduce the burden of pregnancy complications and ultimately the risk of maternal and neonatal morbidity.

TWEETABLE ABSTRACT

Promoting a healthy body mass index and gestational weight gain might reduce the population burden of pregnancy complications.

Clinical Follow-Up in the Rat Experimental Model of African-Trypanosomiasis

Animal models of Human African Trypanosomiasis (HAT) have been developed to understand the pathogenic mechanisms leading to the passage into the neurological phase, most of them referring to histological aspects but not clinical or behavioral data. Our study aimed at defining simple clinical and/or behavioral markers of the passage between the hemolymphatic phase and the meningo-encephalitic stage of the disease. Sprague-Dawley rats (n=24) were infected with Trypanosoma brucei brucei AnTat 1.1E. Food intake and body weight were measured daily from the day of infection until death. Hematocrit was measured twice a week. Behavioral disturbances were evaluated through an Open-field test. A sudden weight loss occurred on the twelfth day after infection, due to a significant drop of food intake starting two days before. The rats developed an anemic state shown by the hematocrit measurements. The Open-field test showed them to be less active and reactive as soon as the second week after infestation. A complementary histological study observed trypanosomes and inflammatory cells in the choroid plexus at the same period. These results are in favor of central nervous system functional disturbances. The observed weight loss is discussed as being a parameter of the entry in the meningo-encephalitic phase. The rat model reproduces neurological symptoms observed in the human disease and may prove to be useful for further neurohistological and therapeutic studies.

Volatile and semi-volatile organic compounds of respiratory health relevance in French dwellings

Over the last decades, the prevalence of childhood respiratory conditions has dramatically increased worldwide. Considering the time spent in enclosed spaces, indoor air pollutants are of major interest to explain part of this increase. This study aimed to measure the concentrations of pollutants known or suspected to affect respiratory health that are present in dwellings in order to assess children's exposure. Measurements were taken in 150 homes with at least one child, in Brittany (western France), to assess the concentrations of 18 volatile organic compounds (among which four aldehydes and four trihalomethanes) and nine semi-volatile organic compounds (seven phthalates and two synthetic musks). In addition to descriptive statistics, a principal component analysis (PCA) was used to investigate grouping of contaminants. Formaldehyde was highly present and above 30 μg/m(3) in 40% of the homes. Diethyl phthalate, diisobutyl phthalate, and dimethylphthalate were quantified in all dwellings, as well as Galaxolide and Tonalide. For each chemical family, the groups appearing in the PCA could be interpreted in term of sources. The high prevalence and the levels of these compounds, with known or suspected respiratory toxicity, should question regulatory agencies to trigger prevention and mitigation actions.

Influence of fetal glutathione S-transferase copy number variants on adverse reproductive outcomes

A nested case-control association study was designed to investigate the influence of maternal and fetal copy number variants (CNVs) on reproductive outcomes. Genotypes of ten CNVs encompassing GST and CYP genes were assessed. Significant associations were only found for child CNV genotypes. In particular, the child GSTM1 insertion allele was associated with prematurity protection (odds ratio, 95% CI: 0.67, 0.51-0.89; P < 0.01), whereas the child GSTT2B insertion allele was associated with an increased risk of being small for gestational age (odds ratio, 95% CI: 1.33, 1.07-1.67; P = 0.01). The study highlights the role of the fetal genome in prenatal development and also the need to analyse CNVs in a systematic manner.

De la psychométrie au handicap neuropsychologique dans la sclérose en plaques. Proposition d’une batterie de dépistage en langue française et facteurs de risque cognitifs

INTRODUCTION

Cognitive deficit in multiple sclerosis (MS) is a frequent early feature in the disease course, which conditions patients' overall disability. The goals of this study were to validate a reproducible brief screening battery written in French and to examine cognitive risk profiles in patients with a mild physical disability.

METHODS

Cognitive performances of 40 patients with EDSS <4.5 were compared with those of a control group. The study was completed with an analysis of socio-demographic, clinical and psychological variables (questionnaires).

RESULTS

Three tests were discriminative with satisfactory predictive values (positive: 88 percent; negative: 96 percent) and a time duration <30 minutes: PASAT (hard condition), backward digit span, learning stage of California Verbal Learning Test. Four variables were associated with cognitive deficit: educational level <11 years, age >40 years, pathological laughing-crying, unemployment.

CONCLUSIONS

Our brief battery is an easy and reproducible tool. Completed with warning signs indicating the need for neuropsychological screening, this tool provides the practitioner with a global means of assessing disease activity and potentially therapeutic efficacy.

Occupational exposure to organic solvent mixtures during pregnancy and the risk of non-syndromic oral clefts

OBJECTIVES

To examine the association between maternal occupational exposure to mixtures of organic solvents during pregnancy and the risk of non-syndromic oral clefts.

METHODS

A case-control study (164 cleft lip with/without cleft palate (CL/P), 76 cleft palate (CP), 236 controls) was conducted in France to investigate the role of maternal occupational exposure to organic solvents at the beginning of pregnancy in the risk of non-syndromic oral clefts. An expert chemist, guided by a detailed description of the women's occupational tasks, assessed exposure for each. Analysis of the findings used logistic regression.

RESULTS

In the control group, 39% of the women who reported working during pregnancy were exposed to at least one type of organic solvent. The risk of oral clefts was associated with oxygenated (for CL/P: OR = 1.8, 95% CI 1.1 to 2.9; and for CP, OR = 1.4, 95% CI 0.7 to 2.7), chlorinated (OR = 9.4, 95% CI 2.5 to 35.3; OR = 3.8, 95% CI 0.7 to 20.7), and petroleum (OR = 3.6, 95% CI 1.5 to 8.8; OR = 1.2, 95% CI 0.3 to 4.9) solvents. The risk of oral clefts increased linearly with level of exposure within the three subgroups of oxygenated solvents we considered (aliphatic alcohols, glycol ethers, and other oxygenated solvents, including esters, ketones, and aliphatic aldehydes).

CONCLUSIONS

Results suggest that maternal occupational exposure to organic solvents during pregnancy may play a role in the aetiology of oral clefts. The limited number of subjects and the problem of multiple exposures require that these results be interpreted cautiously.

Atrazine in municipal drinking water and risk of low birth weight, preterm delivery, and small-for-gestational-age status

BACKGROUND

Atrazine is a herbicide used extensively worldwide. Bioassays have shown that it is embryotoxic and embryolethal. Evidence of adverse reproductive outcomes from exposure in the general population is sparse.

AIMS

To evaluate the association between atrazine levels in municipal drinking water and the following adverse reproductive outcomes: increased risk of preterm delivery, low birth weight (LBW), and small-for-gestational-age (SGA) status.

METHODS

A total of 3510 births that took place from 1 October 1997, to 30 September 1998 were analysed. Atrazine measurements were available for 2661 samples from water treatment plants over the past decade. A seasonal pattern was identified, with atrazine peaking from May to September. The geometric mean of the atrazine level for this period was calculated for each water distribution unit and merged with the individual data by municipality of residence.

RESULTS

Atrazine levels in water were not associated with an increased risk of LBW or SGA status and were slightly associated with prematurity. There was an increased risk of SGA status in cases in which the third trimester overlapped in whole or in part with the May-September period, compared with those in which the third trimester occurred totally from October to April (OR = 1.37, 95% CI 1.04 to 1.81). If the entire third trimester took place from May to September, the OR was 1.54 (95% CI 1.11 to 2.13).

CONCLUSIONS

Low levels of atrazine, a narrow exposure range, and limitations in the exposure assessment partly explain the lack of associations with atrazine. Findings point to the third trimester of pregnancy as the potential vulnerable period for an increased risk of SGA birth. Exposures other than atrazine and also seasonal factors may explain the increased risk.

Risk of congenital anomalies in the vicinity of municipal solid waste incinerators

BACKGROUND

Although municipal solid waste incineration (MSWI) has contributed to increase the overall environmental load of particulate matter containing dioxins and metals, evidence of health consequences to populations is sparse.

AIMS

To assess at a regional level (in southeast France) the impact of these emissions on birth defect rates.

METHODS

Communities with fewer than 50 000 inhabitants surrounding the 70 incinerators that operated at least one year from 1988 to 1997 were studied. Each exposed community (n = 194) was assigned an exposure index estimated from a Gaussian plume model. Poisson models and a reference population of the 2678 unexposed communities in the region were used to calculate relative risks for congenital malformations, adjusted for year of birth, maternal age, department of birth, population density, average family income, and when available, local road traffic.

RESULTS

The rate of congenital anomalies was not significantly higher in exposed compared with unexposed communities. Some subgroups of major anomalies, specifically facial clefts and renal dysplasia, were more frequent in the exposed communities. Among exposed communities, a dose-response trend of risk with increasing exposure was observed for obstructive uropathies. Risks of cardiac anomalies, obstructive uropathies, and skin anomalies increased linearly with road traffic density.

CONCLUSIONS

Although both incinerator emissions and road traffic may plausibly explain some of the excess risks observed, several alternative explanations, including exposure misclassification, ascertainment bias, and residual confounding cannot be excluded. Some of the effects observed, if real, might be attributable to old-technology MSWIs and the persistent pollution they have generated.

The effect of age on sperm stock and egg laying in the parasitoid wasp, Dinarmus basalis

Sperm quantity and quality during storage may be constraints acting on female fecundity and hence fitness. In Hymenoptera, the importance of sperm quality has rarely been considered, despite its central role in reproductive strategies and especially in sex ratio control. In these insects, fertilized eggs develop into females and unfertilized eggs into males. Experiments were conducted on the female wasp, Dinarmus basalis, in the laboratory with and without egg-laying resources (hosts). The first point was to test if sperm age influenced sperm storage by measuring sperm count and viability using a sperm viability test (SYBR14 : propidium iodide). The second point was the influence of prolonged storage in the female genital tract on the quantity, sex ratio and fitness of offspring produced. Results show that sperm viability in the spermatheca does not change significantly with maternal age, and that the sperm stock is not affected when females are deprived of hosts. Egg-laying is gradually restored after 21 days of host deprivation but remains at a low level after 115 days. The fitness of mated D. basalis females is therefore not constrained by sperm quantity or quality and seems to depend on host availability and female age.

Bcl-2/Bax protein expression in heart, slow-twitch and fast-twitch muscles in young rats growing under chronic hypoxia conditions

We have studied the magnitude of apoptosis in heart, slow-twitch skeletal muscle (soleus) and fast-twitch skeletal muscle (gastrocnemius) of rats exposed to 3 weeks in vivo chronic hypoxia. Apoptosis was evaluated biochemically by DNA laddering and by TUNEL and annexin V-staining. The expression of Bax and Bcl-2 proteins was determined by immunohistochemistry and Western blotting. Western blot analysis revealed only a slight difference in Bax expression among the different tissues under normoxic and hypoxic conditions; therefore we can consider that Bax protein is constitutively expressed in muscle tissues. However a singular pattern of Bcl-2 expression was observed among the different tissues under normoxic conditions. Bcl-2 protein was more expressed in fast-twitch glycolytic muscles than in slow-twitch or oxidative muscles with a highest value found in gastrocnemius (4926 +/- 280 AU), followed by soleus (2138 +/- 200 AU) and a very low expression was displayed in the heart muscle (543 +/- 50 AU). After exposure to hypoxia for 21 days (10% O2), Bcl-2 protein expression markedly increased, (44%) in gastrocnemius, (323%) in soleus and (1178%) in heart, with significant differences (p < 0.05 student t-test), reaching a similar threshold of expression in both types of muscles. Furthermore, no sign of apoptosis was detected by TUNEL assay, annexin V-binding assay or DNA electrophoresis analysis. The latter suggested some indiscriminate fragmentations of DNA without apoptosis. In conclusion, we postulate that these protein modifications could represent a adaptative mechanism allowing a better protection against the lack of oxygen in oxidative muscles by preventing apoptosis.

Offspring and sex ratio are independent of sperm management in Eupelmus orientalis females

Sperm stocks in both males and females of the parthenogenetic wasp Eupelmus orientalis were investigated at various points during reproduction and compared to the progeny of females in controlled conditions. One day-old virgin males had approximately 5500 sperm, and from a total of about 1697 sperm transferred per copulation, 21% are stored in the spermathecae by females 24 hours after mating. At the end of the egg-laying period (at least 42 days), 2/5 of the initial amount of sperm remained in this storage organ. This decrease (from approximately 350 to 150) occurred essentially during the first 21 days of egg-laying activity, indicating that the majority of sperm stored were used during this period. Between 21 days and the end of fertile life, the number of sperm remained constant. The mean offspring production throughout reproductive life after one mating was 153, with 56.5% of the daughters laid at the beginning of the laying activity. Sex ratio was entirely female biased during the first 15 days (mean=0.65), then it decreased and became nearly equal after 20 days. Present results propose that females maximize the production of daughters i.e. of inseminated eggs until the 20th day and after this time lay as many daughters and sons despite their still having stored sperm. Physiological constraints due to ageing are proposed to explain this phenomenon.

Changes in flagellar movement of rat spermatozoa along the length of the epididymis: manual and computer-aided image analysis

The different patterns of motility of rat spermatozoa during epididymal transit were studied in vitro using high-speed videomicroscopy. The sperm images were analysed after manual tracing as well as with a computer imaging system. The present work is the first which reports both the swimming path of the sperm head and the characteristics of flagellation in this species. The hook-shaped head of the rat spermatozoa allowed us to demonstrate the two-dimensional (2D) swimming movement compared to the three-dimensional (3D) sperm motion which was mainly related to rotation of the head. Immotile spermatozoa entered the initial segment of the testis and showed rigid flagella. The potential for sperm motility occurred abruptly in the proximal caput region, and different patterns of flagellation were observed: vibrating, motile in place, motile with a static curvature of the midpiece resulting in a spinning motion or a circular path, and forward progressive movement with regular rotation of the head. The pattern of sperm movement became homogeneous in the distal cauda where the whole sperm population swam in a straight line. A static curvature appeared in the midpiece portion when the spermatozoa reached the proximal caput region. The formation of the static curvature was observed on both sides of the rat flagellum which were easily indicated by the head-shaped projection of the head and the axonemal side of the principal wave. As soon as they moved, the spermatozoa successively initiated principal (P) and reverse (R) waves, but the waves were visible only distal to the static curvature. The midpiece stiffness progressively decreased during the epididymal maturation; simultaneously the static curvature showed a larger radius and then disappeared. Consequently, the initiation of waves which was first seen in the distal part of the flagellum of immature cells occurred progressively near the junction with the head of maturing spermatozoa. These changes in sperm motion previously shown in rams and now in rats might be a general phenomenon in mammals. The high resolution of this computer imaging system applied tosperm motion showing a well-characterized "side of the flagellum" should allow sensitive detection of biochemical effects on flagellar beating.

External ionic conditions, internal pH and motility of ram and boar spermatozoa

Internal pH and motility of testicular, epididymal and ejaculated ram and boar spermatozoa were studied as a function of external ionic composition. Internal pH was estimated by the amine distribution method and motility was characterized by percentage of cells that were motile and flagellar beat frequency. Upon dilution in media at different external pH values, internal pH of boar and ram spermatozoa changed rapidly towards the external pH. High external concentrations of Na+ or K+ had no effect on the rate of equilibration and only a slight effect on the final internal pH value, ruling out a role of Na(+)-H+ or K(+)-H+ exchange mechanisms in this process. In both species, a linear relationship was observed between internal and external pH but equilibration was incomplete suggesting that there is a complex regulatory mechanism. This result was unaffected by epididymal maturation and ejaculation. Ram and boar testicular spermatozoa showed no increase in movement after dilution, suggesting that simple changes in internal pH are not a sufficient trigger for motility. At high external pH, internal pH increased and motility of epididymal boar spermatozoa was initiated. Motility of ejaculated boar spermatozoa, and epididymal and ejaculated ram spermatozoa was less dependent upon external pH and affected only very slightly by the internal pH changes. K+ or Na+ had almost no effect on motility just after dilution. After 1 h of incubation, movement decreased. Maintenance of motility in sodium or potassium showed a sharp external pH optimum. Media without Na+ and K+ allowed a better conservation of motility at external pH > 8 for ram epididymal and ejaculated spermatozoa and at external pH > 6 for boar ejaculated spermatozoa.

Evolution of the flagellar waveform of ram spermatozoa in relation to the degree of epididymal maturation

Motility and flagellar movement of ram spermatozoa along the epididymis were analysed in vitro. From the caput to the cauda of the epididymis, the percentage of motile and progressive spermatozoa increases. No flagellar bending was observed in spermatozoa from the testis or the epididymal anterior caput. When spermatozoa reached the distal caput of the epididymis, a static curvature, associated with an initiation of the flagellar beating, appeared on the flagella. This curvature normally disappeared during epididymal transit. Its disappearance was associated with an increase in the flagellar beat efficiency. Our results suggest that the initiation of motility is related to two mechanisms involving: (1) the presence of a transient static curvature, and (2) the establishment of a symmetric regular beating of the flagellum.

Analysis of the flagellar bending waves of ejaculated ram sperm

The variability of flagellar movement, illustrated by the highly heterogeneous nature of the ejaculated sperm population of the ram, was analyzed by the use of a stroboscopic technique and an adapted microphotographic 24 X 36 camera system. The multiple-moving-exposures (MME) records give very distinct successive sequences of the flagellar beats and are particularly suitable for the analysis of bend development and propagation along the tail. With this technique, the parameters of the flagellar bending waves of ejaculated ram sperm have been determined. Most of the sperm have planar flagellar beatings; few are rolling under the conditions of observation. The trajectories of the gametes are mostly linear; nevertheless, some have circular paths. The analysis of bending has been focused on two examples for which the difference in the progressiveness ratio was maximum. The circular pathways for ram spermatozoa are linked to an asymmetry between principal and reverse bend probably induced by differences in wave propagation evidenced along the flagellum. A typical sperm flagellar movement may be related either to the conditions of the observations or to some differences in the maturation process of the sperm.

Effects of 2-deoxy-D-glucose on plasma and adrenal concentrations of corticosterone and aldosterone in standard diet fed and potassium loaded rats

The concentrations of corticosterone, aldosterone and electrolytes (Na+ and K+) were measured in the plasma and adrenal glands, following 2-deoxy-D-glucose (2-DG) treatment (2 injections of 50 mg/ml/100 g body weight) in standard diet fed and potassium loaded rats. In both regimens, 2-DG increased the concentrations of corticosterone mainly in the plasma (+144.8% and 229.5%) and to a lesser extent, in the adrenal glands (+50.9% and 62.5%). Conversely, 2-DG treatment was followed by a steep decline in plasma concentrations of aldosterone both in standard diet fed rats (-65.2%) and in potassium loaded rats (-83.9%), in spite of a marked increase in plasma (+233.3%) and in adrenal (+54.9%) levels of aldosterone after potassium loading; adrenal aldosterone content was essentially the same. Plasma and adrenal electrolytes concentrations and hematocrit varied very little after 2-DG treatment.