The light/dark cycle and suprachiasmatic nucleus rhythmicity are known to have important influences on reproductive function of rodents. We studied reproductive function in female heterozygous and homozygous brain and muscle ARNT-like protein 1 ( Bmal1 , also known as Arntl ) null mice, which lack central and peripheral cellular rhythms. Heterozygous Bmal1 mice developed normally and were fertile, with apparent normal pregnancy progression and litter size, although postnatal mortality up to weaning was high (1.1–1.3/litter). The genotype distribution was skewed with both heterozygous and null genotypes underrepresented (1.0:1.7:0.7; P <0.05), suggesting loss of a single Bmal1 allele may impact on postnatal survival. Homozygous Bmal1 null mice were 30% lighter at weaning, and while they grew at a similar rate to the wild-type mice, they never achieved a comparable body weight. They had delayed vaginal opening (4 days), disrupted estrus cyclicity, and reduced ovarian weight (30%). Bmal1 null mice had a 40% reduction in ductal length and a 43% reduction in ductal branches in the mammary gland. Surprisingly, the Bmal1 mice ovulated, but progesterone synthesis was reduced in conjunction with altered corpora lutea formation. Pregnancy failed prior to implantation presumably due to poor embryo development. While Bmal1 null ovaries responded to pregnant mare serum gonadotropin/human chorionic gonadotropin stimulation, ovulation rate was reduced, and the fertilized oocytes progressed poorly to blastocysts and failed to implant. The loss of Bmal1 gene expression resulted in a loss of rhythmicity of many genes in the ovary and downregulation of Star . In conclusion, it is clear that the profound infertility of Bmal1 null mice is multifactorial.
Reproductive variables in albacore Thunnus alalunga were evaluated by gonad histology in samples of 132 males (58-118 cm fork length, L-F) and 112 females (59-101 cm L-F) that were collected from the western North Pacific Ocean from 2001 to 2006. In the sex ratio examination, males greatly outnumbered females in large adult fish (L-F > 100 cm). Thunnus alalunga exhibited a protracted spawning period from March to September in the waters off eastern Taiwan and the Philippines, and the peak spawning activity occurred in March and April. Minimum sizes associated with the classification of mature fish were 78 and 83 cm L-F for males and females, respectively. In addition, the largest L-F of immature fish were 93 cm for males and 94 cm for females. The spawning frequency estimate in April was 1 center dot 7 days. Batch-fecundity estimates of 21 females (89-99 cm L-F) ranged between 0 center dot 17 and 1 center dot 66 million eggs (mean +/- s.d. = 0 center dot 94 +/- 0 center dot 43). The relative fecundity estimates of the 21 females ranged between 9 center dot 2 and 92 center dot 4 oocytes g-1 body mass (mean +/- s.d. = 50 center dot 5 +/- 22 center dot 8). The results presented in this study provide increased information regarding this species' reproductive-related characteristics than are currently available in stock status determinations.
All organisms face two fundamental trade-offs in the allocation of energetic resources: one between many small versus a few large offspring, and the second between present and future reproduction. Nowhere are these trade-offs more apparent than in the vast range of variation in the sizes of eggs and offspring exhibited among species of marine invertebrates. It has become increasingly clear that, in many taxa of marine organisms, there is also substantial intraspecific variation in the size of eggs and hatchings. This variation has largely been attributed to adaptive maternal effects. In theory, however, the inevitable conflicts of interest that arise in families of sexually reproducing organisms over the optimal distribution of parental resources among siblings could also account for much of this variation in egg and offspring size. Here, we explore the potential impacts of family conflict on offspring traits by comparing the life histories of two exemplar species of marine organisms, the polychaete Boccardia proboscidea and the gastropod Solenosteira macrospira, emphasizing how differences in modes of fertilization and parental care might influence the phenotype and, consequently, the fitness of offspring.
The present study examined the mode and timing of reproduction of poorly understood deep-water octocorals and the environmental factors that may influence their reproductive patterns. Data on reproductive characteristics of the octocoral Drifa glomerata (Alcyonacea: Nephtheidae) collected between 2004 and 2007 at ca. 100–330 m depth off Newfoundland and Labrador (eastern Canada) were compared among years, months and depth ranges. No male gonad was ever observed during the study. The ratio of fertile colonies possessing large pinkish polyps with oocytes/planulae was >50% throughout the year. The number of brooded planula larvae within a single fertile polyp varied between 1 and 10 for a total of approximately 40–3,000 in a whole colony. The size of oocytes and/or planulae was consistently greater in the polyps than in the branchlets, indicating that the development pathway of oocytes to planulae is from the branchlets to the polyps. Although larval production seemed to persist year round, the onset of major planulation events occurred in December–January of two consecutive years, when large mature planulae were released in correlation with the first increase of photoperiod and maximum temperature at 150 m. A second peak in planulation between April and early June followed the phytoplankton bloom. Seasonal trends were more apparent in colonies from <200 m, and the planula index varied among sampling depths and years. Larval release in a live colony under laboratory conditions occurred between January and June 2008, closely following predictions based on field samples.
Studies concerning reproductive biology at the community level have not yet been reported for Caatinga. In this study, we analyzed the flowering phenology, floral longevity, and breeding system of 15 typical woody species in this ecosystem. Flowering occurred mostly during the dry season for ten species. Among dioecious plants, male individuals predominate for two out of three species analyzed. In , a gynodioecious species, female individuals predominate in the population; the number of flowers per inflorescence is the same between hermaphrodite (14.0 ± 4.4) and female (14.8 ± 4.6) individuals, but significant differences are found with respect to fruit set by hermaphrodite (1.9 ± 0.9) and pistillate flowers (4.0 ± 2.4). Self-compatibility occurs in 26.7% of the studied species, whereas 73.3% present obligatory xenogamy. Among self-incompatible species, two have a stylar site of rejection, while self-pollen tubes reach the ovules in five. Late-acting self-incompatibility in constitutes the first record of this mechanism in Sapotaceae. The majority of the species studied have a lower fruit/flower than seed/ovule ratio. Reproduction of woody plants in this arid ecosystem depends upon biotic vectors that can promote cross-pollination and gene flow.
The bluemouth Helicolenus dactylopterus dactylopterus is a zygoparous species that spawns multiple batches of embryos enclosed within a gelatinous matrix. Oocyte development is asynchronous, and the recruitment of secondary growth oocytes occurs continuously during the developing phase, but stops before the start of the first spawning ( i.e. fecundity is determinate). The number of developing oocytes can be estimated as a function of the total length of the fish, its ovary mass and its gonado‐somatic index. Only at the onset of spawning, when potential fecundity is determined, does condition also have a significant effect. The low levels of atresia detected during most of the spawning season show that this mechanism does not substantially affect the process. There is variability both in the spawning interval (with a mean of 2 days) and in the number of embryos comprising every single batch (up to 37 000). Expected effect of fisheries on the reproductive traits of this deep‐sea species is also discussed.
From February 2005 to September 2007, a total of 490 crocodile sharks Pseudocarcharias kamoharai, caught as by-catch in the swordfish and tuna longline fishery that operates in the tropical western Atlantic Ocean, was studied in regard to their reproductive biology. Maximum observed total lengths (L-T) were 1220 and 1090 mm for females and males respectively, with a high proportion of the catch being composed of mature specimens. Sexual maturity was attained at 760-810 mm L-T for males (L-T50 = 800 mm) and 870-980 mm L-T for females (L-T50 = 916 mm). The size at birth was estimated at 415 mm L-T. Temporal variation in gonad morphology and mass suggests that in this region P. kamoharai, an aplacental viviparous species with oophagy, does not show a well-defined reproductive seasonality, with mating and parturition occurring possibly over an extended period of the year. Mean +/- s.d. fecundity was estimated to be 3.9 (+/-0.6) pups per reproductive cycle. (C) 2010 The Authors Journal compilation (C) 2010 The Fisheries Society of the British Isles
Examination of the reproductive biology of Mustelus asterias in the north‐east Atlantic Ocean highlighted apparent geographical variation in maturity, fecundity and ovarian cycle between Atlantic and Mediterranean populations. The stretch total length ( L ST ) and age at 50% maturity for Atlantic males and females were estimated at 78 cm L ST and 4–5 years and 87 cm L ST and 6 years, respectively. Size at maturity of females was considerably smaller than in Mediterranean specimens (96 cm L ST ). Ovarian fecundity ranged from eight to 27 oocytes and uterine fecundity from six to 18 embryos. The gestation period was c. 12 months, followed by a resting period of c. 12 months, resulting in a biennial cycle. Females stored sperm in the oviducal gland and, unlike Mediterranean specimens, no uterine compartments were observed in Atlantic specimens. This study reveals the existence of strong, possibly adaptive, divergence in life‐history traits in an elasmobranch, whose northern populations may be more susceptible to overexploitation than previously believed.
The reproductive biology of the Panama graysby Cephalopholis panamensis was studied from collections and behavioural observations made in the Gulf of California from 2001 to 2006. Histological examinations, particularly the identification of gonads undergoing sexual transition, confirmed a protogynous hermaphroditic sexual pattern. The population structure and mating behaviour provided further support for protogyny. Size and age distributions by sex were bimodal, with males larger and older than females and sex ratios biased towards females. Mating groups consisted of a large male and several smaller females, and courtship occurred in pairs during the evening. Results on spawning periodicity and seasonality were incomplete, but histological data, monthly gonado-somatic indices (I-G) and behavioural observations suggest that adults spawned around the full moon from May to September. Certain aspects of their reproductive biology (e.g. protogyny and low egg production) indicate that C. panamensis is particularly vulnerable to fishing and would benefit from a management policy in Mexico.
The genus Phaius is distributed mainly in pantropical areas, and most species reported are autogamous. In contrast, Phaius delavayi, an alpine plant endemic to temperate zones of China, is strictly pollinator dependent. Only female workers and males of the bumblebee species B. hypnorum and B. lepidus are effective pollinators. The pollinaria are deposited on top of the head or the prothorax of the pollinators. The different depositions of pollinaria are regarded as an adaptation of the chamber dimensions of the flower to the size of the pollinator. The natural fruit set reported here (24.6—37.1%) suggests that pollination is successful in the deceptive P. delavayi. The yellow perianth and sweet floral scent of P. delavayi are important cues in attracting pollinators, while flowering time and mass population are associated with the process of "learning and avoidance" of the rewardless flowers. This orchid, therefore, employs a deceptive pollination strategy with diverse pollinators and pollinaria depositions rather than autogamy as do its congeners.