Terms Of Reproductive Potential Research Articles

The Evolutionary Dynamics of a Sex-Structured Population with Non-Overlapping Generations

This paper proposes and studies a discrete-time model for a sex-structured population with non-overlapping generations under density-dependent regulation of survival. The population is assumed to have genetic variety among individuals in terms of reproductive potential, controlled by a single autosomal diallelic locus. We consider a panmictic population with Mendelian inheritance rules. We examine the stability model and show that increasing the average value of reproductive potential destabilizes the population dynamics. The scenario of stability loss in fixed points via period doubling or Neimark–Sacker bifurcations depends on the intensity of the self-regulation. The growth rate at which the population survives and develops is shown to depend on the fitness of the genotypes and the secondary sex ratio. As a result, the asymptotic genetic composition of the population is determined by the values of the reproductive potentials of the heterozygote and homozygotes, the initial conditions, and the parameter describing the ratio of newborn females to males. With disruptive selection, the influence of external factors changing the current genetic composition of a population can alter the direction of evolution and lead to the extinction of a successful developing population or a gradual population recovery due to evolutionary rescue after a noticeable decline in its abundance.

Sublethal exposure to spinetoram impacts life history traits and dengue virus replication in Aedes aegypti.

Insecticides are anthropogenic environmental stressors and also a common stressor for mosquito vectors. However, the use of insecticides is often guided by short-term efficacy, and the sublethal effect on their target or nontarget species has long been ignored. Here, we analyzed how sublethal exposure of the promising vector-control bioinsecticide spinetoram to Aedes aegypti larvae alter adult performance and susceptibility to dengue virus (DENV) infection. We found that the surviving adult mosquitoes were significantly smaller and exhibited weaker blood-feeding capacity than control females, apart from the extended immature development period. In terms of reproductive potential, although the F0 generation produced a similar number of eggs and offspring during the first gonotrophic cycle, the survival rates of the F1 generations were significantly lower as compared to the control group, suggesting transgenerational sublethal effects on the F1 generation. Notably, surviving adult females had higher DENV-2 viral loads than the control group after spinetoram sublethal exposure. Mechanistically, transcriptomic analysis showed that inhibition of oxidative phosphorylation may function in stimulating DENV production in adult Ae. aegypti. In Aag2 cells, significant accumulation of apoptosis, mitochondrial reactive oxygen species production, and DENV-2 replication by spinetoram exposure consistently support our conclusion. Our study highlights the threat of sublethal spinetoram exposure on outbreaks of mosquito-borne viruses.

Biocidal potential of indigenous isolates of Entomopathogenic Nematodes (EPNs) against tobacco cutworm, Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

BackgroundEntomopathogenic nematodes (EPNs) have been regarded as the most convenient strategy for insect pest management. The native strains of EPNs: Heterorhabditis bacteriophora EUPT-SD, H. bacteriophora EUPT-R, H. bacteriophora EUPT-KN, H. bacteriophora EUPT-K and H. bacteriophora EUPT-H isolated from mid-Himalayan region of Himachal Pradesh were tested in laboratory for their multiplication and virulence against 3rd and 4th larval instars of the tobacco cutworm, Spodoptera litura Fabricius (Lepidoptera: Noctuidae), the serious polyphagous pest affecting a wide range of agricultural crops worldwide.ResultsAll the EPN strains were effective against 3rd and 4th larval instars of S. litura. Insect mortality reached 90–96% after 96 h at nematode concentrations of 150 infective juveniles (IJs)/ml. The insect mortality was also recorded at low concentrations of IJs, but the most exposure period was required. High virulence was shown by H. bacteriophora EUPT-SD 96 and 94%, followed by H. bacteriophora EUPT-R 92 and 90%, H. bacteriophora EUPT-KN 92 and 90%, H. bacteriophora EUPT-K 92 and 90% and H. bacteriophora EUPT-H 92 and 90%, respectively, against 3rd and 4th larval instars in terms of reproductive potential and killing. All the insects were alive in the absolute control.ConclusionUtilization of EPNs for the management of S. litura may be the best method to overcome the insect resistance problems and to manage the population of this insect pest. It may be an effective method and may be a partial substitute of synthetic insecticides, thus minimizing the excessive use of synthetic chemicals. The results demonstrated the potential of indigenous EPNs isolates against S. litura, but before further recommendation, multiplication field trials need to be conducted to confirm their efficacy at farm level.

Evaluation of the effects of photostimulation on freeze-thawed bull sperm cells in terms of reproductive potential.

The aim of this study was to determine the time-dependent effectiveness of photo-stimulation against bovine sperm cells using a multi-wavelength LED (Light Emitting Diode). Spermatological parameters were evaluated for viability, acrosome structure and motility. In addition, the effect of photo-stimulation on frozen-thawed sperm cells subjected to in vitro capacitation was evaluated in terms of changes in mitochondrial membrane potential. The study consisted of two separate experiments and a total of 32 sperm samples obtained from separate bulls were used. All sperm samples were obtained from Holstein bulls using an artificial vagina. Semen was diluted to a final concentration of 92 x 106 spermatozoa per ml in 0.25 ml straws. The sperm cells were frozen using the conventional method. Straws were kept in a 37°C water bath for 20 seconds and diluted 1:4 in phosphate buffered saline (PBS) to eliminate the potentially deleterious effect of glycerol, the main permeable cryoprotectant in the freezing medium for bull sperm. This dilution also helped in the evaluation of sperm quality parameters. In the first experiment, whereas the 15-10-15 showed no differences with the control, other treatments such as 10-10-10, 5-5-5, and 3-1-3 exhibited significantly higher percentages of viable spermatozoa at 24h. The results obtained for acrosome integrity were pretty much similar to those observed in the sperm viability assessment. In effect, while the treatment consisting of 15-10-15 had no positive effects, shorter treatments exerted a much more positive effect. The percentages of acrosome-intact spermatozoa in 2-1-2 and 1-1-1 were significantly higher than those obtained in the control. The significant differences in mitochondrial membrane potential were observed at 0, 2, 4 and 24h post-photo-stimulation in all treatments, except 15-10-15. The highest increase in the percentage of spermatozoa exhibiting high mitochondrial membrane potential was found in 10-10-10, 5-5-5 and 3-1-3 treatments. With regard to total and progressive motility, whereas 10-10-10 was the best regime, 5-5-5 and 3-1-3 treatments also had a positive effect. However, 15-10-15 appeared to have a stimulating effect upon progressive motility at 2h and 4h but later declined and showed no significant differences with regard to the control at 24h. In the second experiment, not immediately after thawing but after having been kept at room temperature for up to 24h, it was observed that there was no statistical difference in terms of viability, acrosome integrity and total/progressive motility between photostimulation and the control group. This indicates that photo- stimulation is less able to exert a beneficial effect when post-thawed sperm are not immediately stimulated. As a result it was determined that photo-stimulation at a pattern of 10-10-10, 5-5-5, 3-1-3 and, to a lesser extent 2-1-2, increases the resilience of frozen-thawed bull sperm when applied upon thawing.

A Survey of Women Who Cryopreserved Oocytes for Non-medical Indications (Social Fertility Preservation)

To evaluate the expectations, experiences, and fertility awareness status of women who underwent social oocyte cryopreservation. Cohort survey study was conducted at an academic medical center. All women who underwent social oocyte cryopreservation between January 2015 and June 2016 were recruited. One hundred thirty-three women were contacted by phone to participate in a survey. The questionnaire investigated the initial motivation towards freezing, intentions to use cryopreserved oocytes, treatment experience, awareness of fertility and knowledge about chances of having a live birth with their frozen oocytes. The mean age at the time of oocyte freezing was 38.5 ± 2.68 years. The average number of mature oocytes cryopreserved was 5.48 ± 6.6 (1–16). Two major motivations were absence of a male partner (40%) and an anticipated age-related fertility decline (42%). Almost 60% overestimated the chances of natural conception, as well as the success of IVF at the age of 40 years. Half of the oocyte bankers reported that fertility declined between ages 35 and 39, but only 28% of patients estimated the live birth rate per cryopreserved oocyte correctly. Overall 98.8% stated that they would recommend oocyte cryopresevation to a friend, and 72% felt more secure in terms of reproductive potential. Despite comprehensive personalized counseling prior to the start of ovarian stimulation, many women do not seem to have a realistic understanding of reproductive aging. Even though gamete cryopreservation provides some insurance, overestimating the effectiveness of oocyte cryopreservation can also lead to a false sense of security. Clinical Trial Registration: 2016.086.IRB1.006

Intraspecific interactions between algae with different nutritional histories.

The diatom Phaeodactylum tricornutum was cultured in five different growth regimes to obtain cells with different composition. Pairs of populations subjected to different treatments were then mixed in a communal culture regime that differed from those of origin. After 6h, the ratio between the two populations was verified by flow cytometry. Alterations in this ratio were found when cells previously grown at 1mM NH4+ were mixed with GeO2 - and 0.5mM NH4+ -grown cells. The nutritional background may thus make cells differently suited to new environmental conditions and afford advantages in terms of reproductive potential. Competitive interactions between populations may result from the differences in the expressed proteome and/or in the availability of tools for regulatory responses. This may have relevance to the persistence of phenotypically neutral variants present in the population best suited to the new condition, after the interaction of the conspecifics with different nutritional histories.

Presowing treatments to breaking seed dormancy of Pterocarya stenoptera C. DC. as an indicator of potential invasiveness

The Small-winged wingnut is a 12 to 20 metres tall, deciduous and fast growing tree with large substantial branches that spread as wide as the tree is tall. The 15 to 30 cm long winged fruit catkins, which turn brown in the autumn, are suspended below the branches. The species is not described by domestic authors in Serbia. The seed was introduced from Sofia (from the Arboretum of the Forestry University of Sofia, Bulgaria - Lesotehniceski universitet, Sofija), and subjected to classical stratification and naked stratification during the period of 1 and 2 months. Germination capacity varied among the treatments. The largest number of germinated seeds was observed in the shorter stratifications, (1 month) the classical (56.5%) and the naked (51.0%) with no significant difference. The values of real germination of all treatments were between 69-88%. High value of RG, compared to GC, indicated that more than 40% of the seeds were empty. However, the results of the control as well as other parameters of seed germination clearly point to the fact that practically no deep embryo dormancy was observed, but the seed is recalcitrant and microbiotic. The results indicate a non-invasive character of the species in terms of reproductive potential.

Effect of Mating Delay on the Reproductive Performance of Cnephasia jactatana (Lepidoptera: Tortricidae)

The leafroller species, Cnephasia jactatana Walker, is an important pest of kiwifruit in New Zealand. The effect of mating delay on its reproductive performance was investigated in the laboratory to provide information for the development of pheromonal pest control measures such as mating disruption. Reproductive performance of both sexes is adversely affected by mating delay. Females are more severely affected by mating delay than males in terms of reproductive potential. Delaying mating in females for 3 and 4 d reduced the reproductive potential by 29 and 88%, respectively. It is suggested that mating disruption may have potential for the control of this species.

Effect of Mating Delay on the Reproductive Performance of <I>Cnephasia jactatana</I> (Lepidoptera: Tortricidae)

The leafroller species, Cnephasia jactatana Walker, is an important pest of kiwifruit in New Zealand. The effect of mating delay on its reproductive performance was investigated in the laboratory to provide information for the development of pheromonal pest control measures such as mating disruption. Reproductive performance of both sexes is adversely affected by mating delay. Females are more severely affected by mating delay than males in terms of reproductive potential. Delaying mating in females for 3 and 4 d reduced the reproductive potential by 29 and 88%, respectively. It is suggested that mating disruption may have potential for the control of this species.

Salpingoscopy in patients with contralateral ectopic pregnancy

Patients who experience a tubal pregnancy have a poor prognosis in terms of reproductive potential and are at increased risk of a repeat EP. Salpingoscopy is a new endoscopic technique that allows the detection of abnormalities of the tubal mucosa. In seven patients with a follow-up longer than 6 months, an IUP occurred only in patients with a normal ampullary mucosa, whereas a recurrent tubal pregnancy occurred in the patient that conceived with an abnormal tubal mucosa. These preliminary results suggest that salpingoscopy may constitute an important prognostic factor in these patients.