objective: this study aimed to evaluate the effect of seasonal variability on the assisted reproductive technique (art) success rate. materials and methods: this study was a descriptive – analytical survey performed on 91 infertile women undergoing  intracytoplasmic sperm injection – embryo transfer (icsi-et) in different seasons. the patients aged less than 35 years old and had normal lh/fsh r...

the genotypes of the melatonin receptor 1a (mtnr1a) were determined by pcr-rflp in the native iranian shall  and karakul breeds of sheep . blood samples were collected from 60 karakul and 50 shall breeds. genomic dna was extracted based on the guanidin thiocyanate-slica gel method. after pcr reaction, pcr products were digested by the mnl1 restriction enzyme. the mtnr1a locus had two genotypes ...

While negative effects of human disturbance on animals living above the ground have been widely reported, few studies have considered effects on animals occupying cavities or burrows underground. It is generally assumed that, in the absence of direct visual contact, such species are less vulnerable to disturbance. Seabird colonies can support large populations of burrow- and cavity-nesting spec...

The assumption that natural selection is an Optlmlslllg process, means that reproductive seasonality in mammals evolved to maximise gene survival. Although the constraints usually imposed on optimality theory are applicable, it can be assumed that periodicity in reproduction represents an adaptation to fluctuation in the availability of potentially limiting resources. In areas where these fluct...

The plainfin midshipman fish, Porichthys notatus, is a seasonal breeding teleost fish for which vocal-acoustic communication is essential for its reproductive success. Female midshipman use the saccule as the primary end organ for hearing to detect and locate "singing" males that produce multiharmonic advertisement calls during the summer breeding season. Previous work has shown that female aud...

Accepted: 29/09/2015 Abstract The control and manipulation of reproduction is the subject of scientific interest for many years. High level of reproductive performance can be achieved under optimum managemental conditions because reproduction is directly affected by various managemental factors. Manipulation of these factors causes changes in reproductive performance. Seasonal breeders are anim...

Seasonal variation in immune function putatively maximizes survival and reproductive success. Day length (photoperiod) is the most potent signal for time of year. Animals typically organize breeding, growth, and behavior to adapt to spatial and temporal niches. Outside the tropics individuals monitor photoperiod to support adaptations favoring survival and reproductive success. Changes in day l...

Through the use of assisted reproductive technology (ART), we will be able to extend the use of genetically superior animals, and perhaps increase the number of offspring. These technologies include such procedures as estrus synchronization, superovulation, artificial insemination, embryo transfer, in vitro fertilization (IVF), and cloning. Because they exhibit seasonal breeding and multiple ov...

In anurans reproductive behavior is strongly seasonal. During the spring, frogs emerge from hibernation and males vocalize for mating or advertising territories. Female frogs have the ability to evaluate the quality of the males' resources on the basis of these vocalizations. Although studies revealed that central single torus semicircularis neurons in frogs exhibit season plasticity, the plast...

Some mammals breed throughout the year, while others breed only at certain times of year. These differences in reproductive behavior can be explained by evolution. We identified positively-selected genes in two sets of species with different degrees of relatedness including seasonal and non-seasonal breeding species, using branch-site models. After stringent filtering by sum of pairs scoring, w...