Prenatal diagnosis of acute bladder distension associated with fetal sacrococcygeal teratoma—a case report

A case report of sacrococcygeal teratoma prenatally diagnosed at 23 weeks of amenorrhea, subsequently causing dilatation of both lower and upper urinary tracts is presented. The importance of repeated ultrasonographic evaluation of fetuses with sacrococcygeal teratoma is discussed.     

水环境中药物污染及迁移转化行为研究进展

药物在人体健康和畜牧业生产中起到了积极的作用。但是未被完全吸收、利用的药物或其代谢物将通过尿液、粪便排泄等途径进入水体,而污水处理厂现有处理技术对其不能有效地去除。虽然药物在水体中的半衰期较短,但是其大量、频繁的使用,仍有可能形成"假性持久性"污染。近年来,在地表水、地下水、饮用水、污泥、土壤、水生物体内等环境介质中都报道有检测到不同浓度水平的药物,其对生态环境和人类健康的影响已引起国际社会广泛关注。欧美一些国家对水环境中药物做了较深入的研究,而我国相关研究报道较少。文章对水环境中药物的来源、污染现状及迁移转化行为等研究进展作了综合分析和讨论,为我国开展相关研究及建立水环境中药物污染的生态风险评价提供参考。     

Competition with flies promotes communal breeding in the burying beetle,Nicrophorus tomentosus

Communal breeding through nest-sharing may benefit cooperating individuals indirectly, in increased inclusive fitness, or directly, when environmental constraints reduce the fitness of solitary breeders. Burying beetles provide extensive parental care and can breed either in pairs or in larger groups of unrelated males and females. Parentage of communally-reared broods is usually shared but is skewed in favor of the individuals of each sex that provide longer care. Females provide care longer than males, and two females are more likely to remain together in the brood chamber than two males are. Flies and other burying beetles are the major competitors for carcasses and this study suggests that it is competition with flies that promotes communal breeding inNicrophorus tomentosus On medium-size carcasses (35–40 g) the presence or absence of oviposition by flies had a significant effect on the size of the brood reared, and on large carcasses (55–60 g) the number of beetles present, two or four, had a significant effect on brood size. On both medium and large carcasses, pairs rearing broods on flyblown carcasses had fewer young than pairs on clean carcasses or foursomes on flyblown carcasses. There was a strong trend for an interaction effect between number of beetles and competition with flies (Table 1). Duration of parental care was not affected by competition with flies except for that of the first male to depart, which provided care longer on flyblown carcasses (Table 2). Pairs and foursomes were equally able to defend the carcass and brood from conspecific intruders and from larger intrudingNicrophorus orbicollis (Table 3).     

Why are larger convict cichlid (Cichlasoma nigrofasciatum) fry sometimes adopted into broods of smaller fry?

Females of Elasmucha grisea defend their eggs and small nymphs against invertebrate predators. Females sometimes guard their clutches side by side on the same birch leaf. We studied benefits of this joint guarding both in the field and in the laboratory. We found that adjacent females had significantly larger clutches than solitary females. In the laboratory, we studied the effectiveness of joint versus single defence against ant (Formica uralensis) predators. We established female pairs from initially singly guarding females by cutting off pieces of leaves with egg clutches and pasting them beside another female guarding her clutch. In the control group the females with their clutches were similarly cut off but these clutches were placed on another leaf without any female. The birch twigs where females guarded their clutches were placed in cages in close proximity to laboratory ant nests. In the experimental treatment, two females guarded their clutches together and at the same nest there was another birch twig without a female. In the control treatment two twigs with one female on each were placed close to another ant nest. Two females defended their clutches significantly more successfully, losing fewer eggs than did the single females. This primitive form of female sociality in parent bugs resembles colonial nesting in birds, where communal defence is also important. However, to our knowledge this is the first experiment where the benefit of joint guarding has been tested directly by manipulating the size of the breeding group rather than by measuring the risk of predation in groups of different size.     

Compensating for the costs of polygyny in hen harriers Circus cyaneus

In polygynous species, the adults are faced with a dilemma during chick rearing. Males must decide how to distribute food between their females and food allocation patterns are often highly unequal. In turn, the females that receive less food from males have to decide how much time to invest in additional hunting. If they spend more time hunting, then they leave their young exposed to weather and predators. However, if they stay at the nest, they increase the risk of their chicks starving. One way that birds may compensate for reduced provisioning is by increasing the size of prey caught. We tested this hypothesis by comparing prey deliveries to nests of hen harriers, Circus cyaneus, with females of different breeding status. As expected, male harriers delivered less food items to the nests of polygynous females, and especially their secondary, or β females. However, both sexes were able to compensate by delivering larger items and there was no difference in the overall mass of food delivered to nests. Moreover, females spent a similar amount of time at the nest, irrespective of status, and there were no overall differences in breeding success. Our results show that polygynous female harriers can compensate for the costs of polygyny, but we suggest that their ability to do so will vary according to the abundance of both large prey and predators.     

Sex ratio and the sexual conflict about brood care in a biparental mouthbrooder

The pay-off of deserting and leaving a mate to care for the offspring alone is generally assumed to depend mainly on the availability of alternative mating partners and on the potential spawning rate of males and females. Eretmodus cyanostictus is a monogamous mouthbrooding cichlid in which the clutch is successively incubated first by the female and then by the male. It has been suggested that parents are constrained to monogamy due to low remating probabilities for both sexes. We tested this hypothesis by varying the sex ratio experimentally. Mate desertion by either sex was not significantly higher when additional potential mates were present (males: 8.3%, females: 0%) than when there were no other same-sex conspecifics present (males: 0%, females: 0%). Males lost their mate to a male intruder during their incubation in 26.7% of cases. Pair members were more active and showed more aggression when same-sex conspecifics were present. Behavioural differences between treatments were strongest during the incubation period of a given sex. If no desertion takes place, sexual conflict may be expressed also on a second level, the amount of parental care each parent provides. Indeed, males took the offspring later when additional females were present, although male incubation time did not differ between treatments. A hitherto undescribed display behaviour of females was clear evidence of a conflict about the timing of shift of young. In conclusion, offering alternative mating opportunities did not strongly favour mate desertion in E. cyanostictus. It rather revealed a conflict between mates about when to shift the young.Communicated by M. Abrahams     

Conservative maternal care in an iteroparous mammal: a resource allocation experiment

When resources are limited, life history theory predicts a trade-off between growth, reproduction and survival. In summer, lactating females of temperate large herbivores such as the white-tailed deer (Odocoileus virginianus) normally have access to abundant forage but also face the high energetic needs of lactation and recovery from winter mass loss. At high population density, however, females may face a trade-off between allocating resources for maintenance and for reproduction. To simulate the effects of increased intra-specific competition at high density, we measured for 2 years how an experimental food restriction of approximately 20% affected current reproduction and body mass changes of adult females and their fawns during the fawning and lactation periods. Fawn survival decreased 35%, and fawn growth decreased 26% in the food-restricted treatment. There was no effect of food restriction on female mass. Irrespective of treatment, however, lactating females gained 30 g/day less than non-lactating females, and females that had weaned a fawn the previous year gained 20 g/day less than females that had not. We conclude that when resources were scarce, females adopted a conservative strategy favouring their own survival, mass recovery and future reproductive potential over their current reproduction, probably to maximise their lifetime reproductive success.     

The dynamics of brood desertion among communally breeding females in the treehopper, Publilia concava

In species that exhibit extended parental care, females sometimes lay eggs communally in order to redistribute the costs of offspring care. Communal egg-laying often involves redundancy in female effort, such that the number of females contributing to reproduction is more than is needed to provide adequate parental care. As a result, a subset of females will often abandon the communal brood, with the time of departure ranging from immediate abandonment after egg-laying (brood parasitism) to delayed abandonment with prolonged care (cooperative breeding). In this paper I approach the parental care dynamics of female-female broods as a desertion game similar to that of mate desertion in species with bi-parental care. I describe a field study of the insect Publilia concava (Hemiptera: Membracidae), a species that exhibits communal oviposition and a full range of egg guarding. This species exhibits full redundancy in female care, with no difference in survival between singly and doubly guarded broods. I find that double guarding is extremely rare in the population, with most communal broods having only one female guard. While this guard was usually the female that initiated the brood, these same females were more likely to abandon when secondary females arrived and when secondary females exhibited longer guarding durations. Paradoxically, the secondary females usually abandoned the broods they visited, resulting in up to 50% of broods with double abandonment. These unguarded broods suffered a 50% reduction in hatching success, reflecting an important risk for primary females that abandon egg masses to secondary females. Overall, P. concava exhibits desertion dynamics similar to mate desertion in vertebrates and it is likely that the theoretical work in this area will be useful for future work that addresses the allocation of parental care among communal breeders.     

Asymmetric costs favor female desertion in the facultatively polyandrous northern flicker (Colaptes auratus): a removal experiment

Previous studies of biparental care in birds have focused on the males contribution and experimental removal of males. Woodpeckers, with a high level of paternal care including nocturnal incubation and brooding by males, offer a meaningful system in which to examine the importance of care by females. I studied the reproductive performance of 17 widowed male and 8 widowed female northern flickers (Colaptes auratus) relative to biparental (control) pairs. Of these single parents all widowed shortly after hatching, only one female abandoned its nest. Single parents boosted their provisioning rates to achieve 83% the provisioning rate of control broods, but reared significantly fewer young and young of poorer quality. However, single males, with 85% of the reproductive success of controls, were more successful than females with 43% the success of controls. Among widowed birds, a not significant lower survival was observed, but the chance of re-pairing with the same partner in a subsequent year was only 16% in the natural population, so long-term costs of desertion may be small. Although females seem to have the incentive and ability to desert, a lack of available males may constrain opportunities. This study demonstrates that when parental care roles are reversed in altricial birds, asymmetric benefits can favor female and not male desertion.     

Prenatal diagnosis of smith–lemli–opitz syndrome is possible by measurement of 7-dehydrocholesterol in amniotic fluid

Amniocentesis was performed at 17.3 weeks in a pregnancy with severe intrauterine growth retardation. Cytogenetic studies on amniocytes were normal, 46,XX, and the pregnancy was continued. The diagnosis of Smith–Lemli–Opitz syndrome was suspected in the neonatal period and confirmed by the presence of 7-dehydrocholesterol (7-DHC) in the plasma (0.4 mmol/l, normal = not detectable) associated with a low total cholesterol concentration (0.4 mmol/l, normal = 2.56 ± 0.23). Retrospective analysis of the amniotic fluid sample revealed an elevated level of 7-DHC (0.022 mmol/l; normal = undetectable). Therefore measurement of 7-DHC levels in amniotic fluid during the second trimester of pregnancy is useful for the prenatal diagnosis of Smith–Lemli–Opitz syndrome in families at risk and should be considered in cases of severe growth retardation of unknown aetiology for which amniotic fluid is available and in which a normal chromosomal pattern in amniocytes is present.