Predicting the response of a long-distance migrant to changing environmental conditions in winter.

Access to high-quality food is critical for long-distance migrants to provide energy for migration and arrival at breeding grounds in good condition. We studied effects of changing abundance and availability of a marine food, common eelgrass (Zostera marina L.), on an arctic-breeding, migratory goose, black brant (Brant bernicla nigricans Lawrence 1846), at a key non-breeding site, Bahía San Quintín, Mexico. Eelgrass, the primary food of brant, is consumed when exposed by the tide or within reach from the water's surface. Using an individual-based model, we predicted effects of observed changes (1991-2013) in parameters influencing food abundance and availability: eelgrass biomass (abundance), eelgrass shoot length (availability, as longer shoots more within reach), brant population size (availability, as competition greater with more birds), and sea level (availability, as less food within reach when sea level higher). The model predicted that the ability to gain enough energy to migrate was most strongly influenced by eelgrass biomass (threshold January biomass for migration = 60 g m-2 dry mass). Conversely, annual variation in population size (except for 1998), was relatively low, and variation in eelgrass shoot length and sea level were not strongly related to ability to migrate. We used observed data on brant body mass at Bahía San Quintín and annual survival to test for effects of eelgrass biomass in the real system. The lowest observed values of body mass and survival were in years when biomass was below 60 g m-2, although in some years of low biomass body mass and/or survival was higher. This suggests that the real birds may have some capacity to compensate to meet their energy demands when eelgrass biomass is low. We discuss consequences for brant population trends and conservation.

FishMORPH - An agent-based model to predict salmonid growth and distribution responses under natural and low flows.

Predicting fish responses to modified flow regimes is becoming central to fisheries management. In this study we present an agent-based model (ABM) to predict the growth and distribution of young-of-the-year (YOY) and one-year-old (1+) Atlantic salmon and brown trout in response to flow change during summer. A field study of a real population during both natural and low flow conditions provided the simulation environment and validation patterns. Virtual fish were realistic both in terms of bioenergetics and feeding. We tested alternative movement rules to replicate observed patterns of body mass, growth rates, stretch distribution and patch occupancy patterns. Notably, there was no calibration of the model. Virtual fish prioritising consumption rates before predator avoidance replicated observed growth and distribution patterns better than a purely maximising consumption rule. Stream conditions of low predation and harsh winters provide ecological justification for the selection of this behaviour during summer months. Overall, the model was able to predict distribution and growth patterns well across both natural and low flow regimes. The model can be used to support management of salmonids by predicting population responses to predicted flow impacts and associated habitat change.

Shorebird predation of horseshoe crab eggs in Delaware Bay: species contrasts and availability constraints.

1. Functional responses -- the relationship between resource intake rate and resource abundance -- are widely used in explaining predator-prey interactions yet many studies indicate that resource availability is crucial in dictating intake rates. 2. For time-stressed migrant birds refuelling at passage sites, correct decisions concerning patch use are crucial as they determine fattening rates and an individual's future survival and reproduction. Measuring availability alongside abundance is essential if spatial and temporal patterns of foraging are to be explained. 3. A suite of shorebird species stage in Delaware Bay where they consume horseshoe crab Limulus polyphemus eggs. Several factors including spawning activity and weather give rise to marked spatial and temporal variation in the abundance and availability of eggs. We undertook field experiments to determine and contrast the intake rates of shorebird species pecking for surface and probing for buried eggs. 4. Whether eggs were presented on the sand surface or buried, we demonstrate strong aggregative responses and rapid depletion (up to 80%). Depletion was greater at deeper depths when more eggs were present. No consistent give-up densities were found. Type II functional responses were found for surface eggs and buried eggs, with peck success twice as high in the former. Maximum intake rates of surface eggs were up to 83% higher than those of buried eggs. 5. Caution is needed when applying functional responses predicted on the basis of morphology. Our expectation of a positive relationship between body size and intake rate was not fully supported. The smallest species, semipalmated sandpiper, had the lowest intake rate but the largest species, red knot, achieved only the same intake rate as the mid-sized dunlin. 6. These functional responses indicate that probing is rarely more profitable than pecking. Currently, few beaches provide egg densities sufficient for efficient probing. Areas where eggs are deposited on the sand surface are critical for successful foraging and ongoing migration. This may be especially true for red knot, which have higher energetic demands owing to their larger body size yet appear to have depressed intake rates because they consume smaller prey than their body size should permit.

When enough is not enough: shorebirds and shellfishing.

In a number of extensive coastal areas in northwest Europe, large numbers of long-lived migrant birds eat shellfish that are also commercially harvested. Competition between birds and people for this resource often leads to conflicts between commercial and conservation interests. One policy to prevent shellfishing from harming birds is to ensure that enough food remains after harvesting to meet most or all of their energy demands. Using simulations with behaviour-based models of five areas, we show here that even leaving enough shellfish to meet 100% of the birds' demands may fail to ensure that birds survive in good condition. Up to almost eight times this amount is needed to protect them from being harmed by the shellfishery, even when the birds can consume other kinds of non-harvested prey.

Day 3 morphology is a poor predictor of blastocyst quality in extended culture.

OBJECTIVE: To determine how the quality of blastocysts formed on day 5/6 of extended culture compares with their morphology on day 3. DESIGN: Retrospective observational study of IVF laboratory records. SETTING: Private assisted reproduction clinic. PATIENT(S): 101 IVF cycles in which 5 to 25 embryos were produced. The average maternal age was 33.1 years. INTERVENTION(S): Embryos were individually cultured in vitro in sequential media for an extended time to enable use of blastocysts for fresh transfer or cryopreservation. MAIN OUTCOME MEASURE(S): Comparison of embryo quality for putative ET or cryopreservation on day 3 with quality of embryos used for actual ET and cryopreservation on day 5/6. RESULT(S): Of 1,263 cleaving embryos, 559 were judged to have been suitable for use on day 3; 355 would have been used for ET (average per ET, 3.5) and 204 would have been frozen (equivalent to 44% utilization). In actuality, 471 blastocysts were used on day 5/6, of which 234 were transferred (average per ET, 2.3), and 237 were frozen (equivalent to 37% utilization). Only 48% embryos that would have been chosen for ET and/or cryopreservation on day 3 were eventually used in such a manner at the blastocyst stage. Historically, the rate of viable pregnancy from day 3 transfers was 30.5% per transfer; this rate increased to 45% with routine day 5/6 transfers. CONCLUSION(S): Extended culture of human embryos seems to increase discrimination of potential embryonic viability. Criteria for embryo selection on day 3 seem to be inadequate. Extended in vitro culture may therefore be an effective means of optimizing IVF clinical success.

Otoacoustic emissions in normal-cycling females.

The purpose of this study was to determine if the menstrual cycle influences the amplitude of transient (TEOAEs) and distortion-product (DPOAEs) otoacoustic emissions. Thirteen normal-hearing, normal-cycling females were monitored weekly for 12 weeks. TEOAE and DPOAE amplitudes were analyzed to determine if amplitude changes could be detected and correlated to phases of the menstrual cycle. No systematic amplitude changes were observed, demonstrating that evoked OAEs are unaffected by physiologic changes associated with the menstrual cycle.

Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women.

The effects of soy protein (40 g/d) containing moderate and higher concentrations of isoflavones on blood lipid profiles, mononuclear cell LDL receptor messenger RNA, and bone mineral density and content were investigated in 66 free-living, hypercholesterolemic, postmenopausal women during a 6-mo, parallel-group, double-blind trial with 3 interventions. After a control period of 14 d, during which subjects followed a National Cholesterol Education Program Step I low-fat, low-cholesterol diet, all subjects were randomly assigned to 1 of 3 dietary groups: Step I diet with 40 g protein/d obtained from casein and nonfat dry milk (CNFDM), Step I diet with 40 g protein/d from isolated soy protein containing 1.39 mg isoflavones/g protein (ISP56), or Step I diet with 40 g protein/d from isolated soy protein containing 2.25 mg isoflavones/g protein (ISP90). Total and regional bone mineral content and density were assessed. Non-HDL cholesterol for both ISP56 and ISP90 groups was reduced compared with the CNFDM group (P < 0.05). HDL cholesterol increased in both ISP56 and ISP90 groups (P < 0.05). Mononuclear cell LDL receptor mRNA was increased in subjects consuming ISP56 or ISP90 compared with those consuming CNFDM (P < 0.05). Significant increases occurred in both bone mineral content and density in the lumbar spine but not elsewhere for the ISP90 group compared with the control group (P < 0.05). Intake of soy protein at both isoflavone concentrations for 6 mo may decrease the risk factors associated with cardiovascular disease in postmenopausal women. However, only the higher isoflavone-containing product protected against spinal bone loss.

Environmental endocrine modulators and human health: an assessment of the biological evidence.

Recently, a great deal of attention and interest has been directed toward the hypothesis that exposure, particularly in utero exposure, to certain environmental chemicals might be capable of causing a spectrum of adverse effects as a result of endocrine modulation. In particular, the hypothesis has focused on the idea that certain organochlorine and other compounds acting as weak estrogens have the capability, either alone or in combination, to produce a variety of adverse effects, including breast, testicular and prostate cancer, adverse effects on male reproductive tract, endometriosis, fertility problems, alterations of sexual behavior, learning disability or delay, and adverse effects on immune and thyroid function. While hormones are potent modulators of biochemical and physiological function, the implication that exposure to environmental hormones (e.g., xenoestrogens) has this capability is uncertain. While it is reasonable to hypothesize that exposure to estrogen-like compounds, whatever their source, could adversely affect human health, biological plausibility alone is an insufficient basis for concluding that environmental endocrine modulators have adversely affected humans. Diethylstilbestrol (DES) is a potent, synthetic estrogen administered under a variety of dosing protocols to millions of women in the belief (now known to be mistaken) that it would prevent miscarriage. As a result of this use, substantial in utero exposure to large numbers of male and female offspring occurred. Numerous studies have been conducted on the health consequences of in utero DES exposure among the adult offspring of these women. There are also extensive animal data on the effects of DES and there is a high degree of concordance between effects observed in animals and humans. The extensive human data in DES-exposed cohorts provide a useful basis for assessing the biological plausibility that potential adverse effects might occur following in utero exposure to compounds identified as environmental estrogens. The effects observed in both animals and humans following in utero exposure to sufficient doses of DES are consistent with basic principles of dose response as well as the possibility of maternal dose levels below which potential non-cancer effects may not occur. Significant differences in estrogenic potency between DES and chemicals identified to date as environmental estrogens, as well as an even larger number of naturally occurring dietary phytoestrogens, must be taken into account when inferring potential effects from in utero exposure to any of these substances. The antiestrogenic properties of many of these same exogenous compounds might also diminish net estrogenic effects. Based on the extensive data on DES-exposed cohorts, it appears unlikely that in utero exposure to usual levels of environmental estrogenic substances, from whatever source, would be sufficient to produce many of the effects (i.e., endometriosis, adverse effects on the male reproductive tract, male and female fertility problems, alterations of sexual behavior, learning problems, immune system effects or thyroid effects) hypothesized as potentially resulting from exposure to chemicals identified to date as environmental estrogens.

Modulation of implantation-associated integrin expression but not uteroglobin by steroid hormones in an endometrial cell line.

In order to test the hypothesis that integrin and uteroglobin (UG) expression in cultured endometrial cells are affected by hormone treatment, Ishikawa-CH endometrial cancer cells were cultured and exposed to oestradiol or oestradiol and progesterone regimens and assayed using immunohistochemistry. We evaluated the intensity of immunohistochemical staining for the integrin monomers alpha(v) and beta1, the dimers alpha(v)beta3 and alpha(v)beta6, and for the secretory protein uteroglobin under various experimental conditions. Cells grown in control media stained positively for the integrin monomers alpha(v) and beta1, the dimer alpha(v)beta3, and for UG. Oestradiol and sequential oestradiol/progesterone reversibly suppressed staining for the dimer alpha(v)beta3. Hormone treatment had no effect on the staining of the beta1 and alpha(v) monomers or UG. The alpha(v)beta6 dimer antibody did not stain under any experimental treatment conditions. These data indicate that expression of the integrin complex alpha(v)beta3 is reversibly suppressed by oestradiol in Ishikawa cells and that these cells may be a good model for studying hormone-driven molecular changes in endometrium.

Increasing clinical pregnancy rates after IVF/ET. Can immunosuppression help?

OBJECTIVE: To evaluate the safety and efficacy of immunosuppression as an adjunct to improving the success of in vitro fertilization/embryo transfer (IVF-ET). STUDY DESIGN: A randomized, double-blind, placebo-controlled clinical trial. RESULTS: Seventy-five patients were randomized to receive either prednisone (39 patients, 51%) or placebo (36 patients, 49%). Patients in both groups had similar ages and numbers of preembryos transferred. CONCLUSION: Both the implantation and clinical pregnancy rates were higher in the prednisone group (16% vs. 11% and 43.5% vs. 32.3%, respectively). However, these differences did not achieve statistical significance. Evaluation of the ongoing pregnancy rate revealed little difference between the prednisone-treated patients (30.7%) and those receiving placebo (28.0%). There were no side effects reported by patients in either group.

Comparison of magnetic resonance imaging and transvaginal ultrasonography with hysterosalpingography in the evaluation of women exposed to diethylstilbestrol.

OBJECTIVE: To compare the ability of magnetic resonance imaging (MRI) and transvaginal ultrasound (TV-US) with that of hysterosalpingography (HSG) in detecting uterine abnormalities caused by in utero diethylstilbestrol (DES) exposure. STUDY DESIGN: The study was a prospective MRI and TV-US blind comparison of DES-exposed and nonexposed subjects who had had previous HSG for infertility evaluation. RESULTS: MRI identified uterine constrictions in 60% of patients and T-shaped uteri in 25% of DES-exposed patients with HSG-confirmed abnormalities. TV-US did not identify uterine constrictions or T-shaped uteri in DES-exposed patients. CONCLUSION: HSG must still be considered the preferred method in evaluating DES-related uterine abnormalities. HSG-defined uterine abnormalities associated with in utero DES exposure were variably identified by MRI and not at all by TV-US.

Achieving multiple-order embryo transfer identifies women over 40 years of age with improved in vitro fertilization outcome.

OBJECTIVE: To define factors in patients > or = 40 years that may improve outcome and provide prognosis for success in IVF-ET. DESIGN: Retrospective. SETTING: University infertility center. PATIENTS: Patients (n = 501) undergoing IVF-ET from 1987 to 1994. INTERVENTIONS: IVF-ET (n = 713 cycles) with GnRH-analogue suppression and hMG stimulation. MAIN OUTCOME MEASURES: We evaluated data including age, diagnosis, prestimulation (day 3) FSH and E2, hMG ampules used, days of monitoring, follicle number and size, maximum E2, ova retrieved, cancellation rate, clinical pregnancy, nidation, and miscarriage rates. RESULTS: Overall, patients > or = 40 years had significantly decreased pregnancy rates (PRs), response to stimulation, and increased miscarriage rates. However, if these patients had four or more embryos transferred, their response and PRs (34.4% per ET) were not significantly different from younger women (47.7% per ET). The majority (77.8%) of pregnancies in women > or = 40 years occurred when four or more embryos were transferred. CONCLUSION: A subset (49%) of women > or = 40 years undergoing IVF-ET will respond to ovarian stimulation well enough to result in four or more embryos available for transfer with a resultant PR similar to that observed in younger patients. We recommend consideration of an attempt at IVF-ET before recommending oocyte donation.

Immunocytochemical localization of growth factors and their receptors in human pre-embryos and Fallopian tubes.

We utilized indirect immunocytochemistry to demonstrate the presence of growth factors and their receptors in human pre-embryos and Fallopian tubes. In pre-embryos, only transforming growth factor-alpha (TGF-alpha) and the intracellular domain of epidermal growth factor receptor (EGFR) were found at the 4-cell stage. In 8- to 14-cell pre-embryos, TGF-alpha, the intracellular and extracellular domains of EGFR, and insulin-like growth factor-I and its receptor were found. Antibodies against TGF-alpha stained all Fallopian tube specimens, while the extracellular domains of EGFR was only found in specimens from patients with either blood type A or AB. These results suggest a cross-reactivity between the extracellular domain of the EGFR and blood group antigens. Our novel demonstration of growth factor receptor staining in human pre-embryos shows that growth factor receptor localization is dependent on the developmental stage of human pre-embryos. We have also established a potentially important link between the Fallopian tube which secretes growth factors and the localization of growth factor receptors in pre-embryos. These findings are compatible with the hypothesis that tubal secretions are embryotrophic for the early development of the pre-embryo.

Prognostic value of day 3 estradiol on in vitro fertilization outcome.

OBJECTIVE: To evaluate the prognostic value of day 3 E2 levels, independent of day 3 FSH levels, on responses to ovulation induction and subsequent pregnancy rates (PRs) in IVF-ET patients. DESIGN: Prospective, observational. SETTING: University-based tertiary care and private reproductive endocrine-infertility units. PATIENTS AND INTERVENTIONS: A total of 225 patients underwent 292 IVF cycles with luteal phase GnRH agonist suppression and hMG stimulation. MAIN OUTCOME MEASURES: We evaluated response and outcome data including age, day 3 FSH and E2 levels from a menstrual cycle before IVF, ampules of hMG used, maximum E2 level, cancellation rates, and clinical PR. RESULTS: Despite similar age, number of ampules of hMG, and peak E2 levels, patients with an elevated E2 level (E2 > or = 80 pg/mL) (conversion factor to SI unit, 3.671) on day 3 of a cycle before IVF-ET achieved a lower PR per initiated cycle (14.8% versus 37.0%) and had a higher cancellation rate (18.5% versus 0.4%) compared with those with E2 levels < 80 pg/mL. Even when patients with elevated FSH levels (FSH > or = 15 mIU/mL) (conversion factor to SI unit, 1.00) were excluded (leaving 279 cycles), those with an elevated day 3 E2 still had a lower PR per initiated cycle (14.8% versus 38.9%) and maintained a higher cancellation rate (18.5% versus 0.4%). When the day 3 E2 was > or = 100 pg/mL there was a 33.3% cancellation rate and no pregnancies were achieved. CONCLUSION: Patients who presented with an elevated day 3 E2 (> or = 80 pg/mL) in a cycle before IVF-ET had a higher cancellation rate and achieved a lower PR independent of FSH level. A day 3 E2 level, in addition to a day 3 FSH level, appears very helpful in prospectively counseling patients regarding cancellation risk and ultimate IVF-ET success.

Contributions of exercise, body composition, and age to bone mineral density in premenopausal women.

The purpose of this cross-sectional study were to determine whether exercisers have greater bone mineral density (BMD) than nonexercisers, whether aerobic dancers have greater BMD than walkers, and to determine the contributions of energy expenditure, body composition, and dietary factors to spine and femur BMD. Measurements were obtained on 93 eumenorrheic women (walkers N = 28; aerobic dancers, N = 34; nonexercisers, N = 31) ages 25-41 yr; lumbar spine and proximal femur BMD, body composition, physical activity, and nutrient intakes. Mean height, weight, and body mass index and median age and calcium intakes were similar for the three groups. Mean (+/- SD) values of the spine, total femur, and femoral neck BMD, respectively, were: walkers (1.092 (+/- 0.098), 0.947 g.cm-2), dancers (1.070 (+/- 0.124), 0.990 (+/- 0.104), 0.908 (+/- 0.106) g.cm-2), and nonexercisers (1.020 (+/- 0.112), 0.887 (+/- 0.073), 0.792 (+/- 0.089) g.cm-2) multiple regression analyses indicated that exercise contributed to spine (P = 0.018), total femur (P =0.012), and femoral neck (P < 0.0001) BMD, whereas type of exercise (aerobic dance vs walking) did not (P > 0.05). Total femoral BMD was influenced by exercise (P = 0.012) and energy expenditure (P = 0.023), while vertebral BMD was influenced by age (P = 0.0067), body weight (P = 0.017), and exercise (P = 0.018). These findings suggest that walking and aerobic dance exercise may provide physically active premenopausal women with greater lumbar and femoral BMD than sedentary females.

A comparison of bone mineral densities among female athletes in impact loading and active loading sports.

The purpose of this study was to compare bone mineral densities (BMD) of collegiate female athletes who compete in impact loading sports; volleyball players (N = 8) and gymnasts (N = 13), to a group of athletes who participate in an active loading sport; swimmers (N = 7), and a group of controls (N = 17). All of the volleyball, swimming, and control subjects were eumenorrheic (10-12 cycles/year), whereas two of the gymnasts were amenorrheic (0-3 cycles/year), eight were oligomenorrheic (4-8 cycles/year), and three were eumenorrheic (10-12 cycles/year). Lumbar spine, proximal femur, and total body BMD were measured with dual-energy X-ray absorptiometry. The groups were compared with respect to the following regions: lumbar spine (L1-4); femoral neck; Ward's triangle; right and left arms; right and left legs; pelvis; and torso. When controlling for differences in height and weight the impact loading group (volleyball and gymnastic) had significantly greater BMD at the lumbar spine, femoral neck, Ward's Triangle, and total body when compared to the active loading (swimming) and control groups. The regional analysis from the total body scan revealed that the gymnasts had significantly (p < 0.05) greater BMD than all other groups at the right and left arm sites. The impact loading groups (gymnastic and volleyball) had a greater BMD in the legs and pelvis than the active loading (swimming) and control groups. Furthermore, the impact loading group had a greater torso BMD than the control group. There were no differences at any site between the active loading group (swimming) and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Lineage tracing demonstrates that blastomeres of early cleavage-stage human pre-embryos contribute to both trophectoderm and inner cell mass.

We injected a fluorescent lineage tracer (Texas Red-lysine-dextran) into individual blastomeres of donated human diploid 2- to 8-cell pre-embryos and cultured them to blastocysts. Once pre-embryos reached the expanded blastocyst stage, they were fixed and examined in a scanning confocal microscope to identify the location of fluorescent tracer. In successfully injected pre-embryos that developed to expanded blastocysts, we found that randomly injected blastomeres formed both trophectoderm (TE) and inner cell mass (ICM). More labelled progeny were found in TE than in ICM. Our results show that individual early blastomeres are not yet committed to form either TE or ICM but instead can form both rudiments.