A diet supplemented with l-carnitine improves the sperm quality of Piétrain but not of Duroc and Large White boars when photoperiod and temperature increase

It has been reported that a diet supplemented with l-carnitine can improve sperm quality in some mammalian species. Against this background, the current study seeks to determine the effects of feeding l-carnitine (625 mg·day⁻¹) on boar semen characteristics (ejaculate volume, sperm concentration, sperm viability, acrosome and mitochondrial sheath integrity, sperm motility, sperm morphology, and osmotic resistance of spermatozoa) in three different porcine breeds (Sus domesticus) (Piétrain, Duroc, and Large White) exposed to natural environmental changes in temperature and photoperiod over a 20-wk period (February to July 2007). One hundred twenty boars (40 per breed) were randomly separated into two groups (60 boars each): the first (20 boars per breed) was fed a control diet and the second (also 20 males per breed) the same diet supplemented with l-carnitine (625 mg·day⁻¹). Whereas the l-carnitine supplement did not affect ejaculate volume, concentration, motility, viability, or the osmotic resistance of spermatozoa, it did improve sperm morphology in Piétrain boars by reducing the percentage of immature spermatozoa when the temperature and the photoperiod increased. Conversely, no effect on sperm morphology from supplementing feed with l-carnitine was observed in both Duroc and Large White breeds. We can therefore conclude that the addition of l-carnitine to the diet of males may maintain the level of normal sperm morphology in Piétrain boars when a drop in sperm quality occurs (due to increases in photoperiod and temperature), without affecting the other sperm quality parameters.     

Semen quality of postpubertal boars during increasing and decreasing natural photoperiods

The present study analyses the effects of increasing and decreasing photoperiods on the semen quality of 20 selected postpubertal Landrace boars. The boars were exposed, throughout 75 days, to increasing and decreasing photoperiods of natural light, a constant temperature of 21 +/- 1 degrees C and 60-70% of humidity, fed with a nutritious diet and, submitted to a rhythm of semen collection of twice a week. During the last 2 weeks of each treatment, semen samples were analysed and the parameters measured were: ejaculate volume and pH, sperm concentration, sperm production and the number of semen doses per ejaculate, sperm vitality, sperm motility, osmotic resistance of spermatozoa and sperm morphology. The comparative analysis between increasing and decreasing photoperiods indicated that the semen quality of boars exposed to a decreasing photoperiod was reduced as a consequence of decreases in sperm concentration, sperm production and the number of semen doses. There was no difference between increasing and decreasing photoperiods in terms of sperm vitality and sperm motility, nor in the osmotic resistance of spermatozoa to isotonic and hypotonic media. The analysis of sperm morphology showed significantly lower frequencies of mature and immature spermatozoa with a distal cytoplasmic droplet, and significantly higher frequencies of immature spermatozoa with a proximal droplet in boars exposed to the decreasing photoperiod. These results indicate that the sperm quality of the selected boars decreased during decreasing photoperiods, in comparison with increasing photoperiods, mainly due to impaired testicular function.     

Growth,testicular and endocrine function of boars exposed to 8, 16 or 24 hours of light daily before puberty

Sixty Yorkshire boars were used in two replicates to evaluate the influence of duration of photoperiod on growth, testicular and reproductive endocrine function. Boars born in May and July were exposed to either 8, 16 or 24 h of fluorescent light (200 1x) daily between 2 and 8 months of age. Body weights were obtained at 2-week intervals. At 4, 6 and 8 months of age, venous cannulae were placed in five boars from each treatment and samples of serum were collected to evaluate concentrations of luteinizing hormone (LH) and testosterone. Samples of boars from each treatment were castrated at 6 and 8 months of age, and weights and sperm content of the testes and epididymides were determined. Body weights of boars were similar for all treatments throughout the experiment. Duration of photoperiod did not affect weights of the testes or epididymides or total numbers of sperm within these tissues at either 6 or 8 months of age. Testicular and epididymidal weights and epididymidal sperm numbers increased between 6 and 8 months of age. Concentrations of luteinizing hormone (LH) and testosterone in serum at 4, 6 or 8 months of age were not affected by duration of photoperiod. These results indicate that growth rate and testicular development of prepubertal Yorkshire boars born in May and July are not influenced by duration of photoperiod.     

Effects of exposing boars to different artificial light regimens on semen plasma markers and "in vivo" fertilizing capacity

This study was designed to assess the effects of exposing boars to an artificial photoperiod on semen quality in terms of sperm concentration, sperm vitality, sperm motility and acrosome integrity. We also determined biochemical semen plasma variables, such as total protein concentration, phosphorylated tyrosine residues and fructose, glucose and sorbitol contents, along with their effects on the fertility, prolificacy and libido of the boars. Three groups of 10 males were kept for 3 months under experimental conditions of 24, 12 and 0 h of artificial light, and a constant temperature of 21 +/- 1 degrees C and 60-75% humidity. The animals were fed a nutritious diet and subjected to semen collection twice per week. Semen samples were analyzed throughout the entire experimental period. Our results indicate that, while the extreme photoperiods (0 and 24 h of light) affected semen quality in terms of sperm concentration, acrosome integrity and semen volume, its fertilizing capacity was only significantly reduced under conditions of absolute darkness. Sperm motility was found to be a poor indicator of fertilizing ability, while other sperm factors, such as acrosome integrity or other functional variables seemed to behave better. The photoperiod was found to affect the production of accessory sex gland secretions more than their composition. In addition, light effects on fertility, prolificacy and libido seemed to be achieved through independent mechanisms.     

Characterization of the semen quality of postpuberal boars with spontaneous unilateral abdominal cryptorchidism on the right side.

In recent studies, we found that the ectopic testis from postpuberal boars with unilateral abdominal cryptorchidism does not produce sperm. Therefore, in these males, the seminal characteristics can be used as indicators of the activity of the scrotal testis and its epididymis and also the accessory glands. The semen quality (ejaculate volume, cell-rich fraction volume, sperm concentration, sperm vitality, sperm motility, sperm morphology and cephalic stability of spermatozoa) was evaluated in healthy postpuberal boars and in postpuberal boars with unilateral abdominal cryptorchidism on the right side. In comparison with the healthy boars, the unilateral abdominal cryptorchid boars showed a significant decrease of the ejaculate volume, sperm concentration and sperm motility. The low sperm concentration indicated that unilateral abdominal cryptorchidism severely impairs the sperm production of the scrotal testis. The decrease of ejaculate volume was attributed to an abnormal activity of the accessory glands. The alterations in sperm motility develop as a result of dysfunctions in the epididymal epithelium and/or the accessory glands. The sperm vitality, sperm morphology and cephalic stability of spermatozoa maintained normal values; therefore, at testicular level, despite the low sperm production, the germ cell differentiation is not disturbed. At epididymal level, the morphological maturation of spermatozoa is not altered.     

Effects of dietary L-carnitine supplementation on semen characteristics in boars

In some species, dietary supplementation with L-carnitine has been reported to increase sperm concentration and sperm motility. The objective of these experiments was to test the hypothesis that L-carnitine supplementation improves the semen characteristics of boars. In Experiment 1, boars (258 days of age) were fed daily a control diet (n = 9) or the control diet plus L-carnitine (500mg per day; n = 9 ). Semen was collected weekly from Weeks 0 to 15 and on 4 consecutive days during Week 16. Experiment 2 was similar to Experiment 1 except boars ( n = 10 per treatment) were 504 days of age. For the weekly and intensive collections there were no consistently positive effects of treatment on semen volume, sperm concentration, total spermatozoa, or sperm motility. Spermatozoa from L-carnitine-treated boars did not display an enhanced ability to maintain motility during 7-day liquid storage. In conclusion, indicators of semen quality were not enhanced by dietary supplementation of L-carnitine in boars.     

Effects of season and breed on sperm acrosin activity and semen quality of boars

Acrosin activity and semen quality (sperm concentration, ejaculate volume and number of spermatozoa) were assessed from March 1997 to March 1998 in semen of Large White, Pietrain and Duroc x Pietrain boars. Semen quality varied with season, including high production of spermatozoa in autumn and winter and low production in summer. Semen quality also differed across breeds. Acrosin activity of boar spermatozoa was not affected by breed (range 3.16-3.32 mU/10(6) spermatozoa), but exhibited distinct seasonal changes. Monthly changes in acrosin activity were parallel to changes in number of sperm in the ejaculate from November to March. On the other hand, dramatic changes in acrosin activity between July and October (range 1.85-4.59 mU/10(6) spermatozoa) were not paralleled by similar changes in number of ejaculated sperm. These fluctuations in acrosin activity may reflect either changes in sperm acrosin production or disturbances to sperm membranes, probably related to effects of high summer temperatures during spermatogenesis. Results confirmed seasonal and breed-related differences in boar semen quality characteristics.     

Association study and expression analysis of porcine ESR1 as a candidate gene for boar fertility and sperm quality

Male fertility is impaired through the lack of ESR1 (Estrogen Receptor 1) but little is known about the ESR1 roles in boar spermatogenesis and fertility. Therefore, this research was aimed at investigating the association with sperm quality and boar fertility traits in a total of 300 boars both from purebred Pietrain and Pietrain × Hampshire crosses. A SNP in coding region of ESR1g.672C>T in exon 1 was associated with sperm motility (P<0.05) and plasma droplet rate (P<0.01) while the polymorphism in non-coding region of ESR1g.35756T>C in inton 1 was associated with non-return rate (P<0.05). Furthermore, to analyse the mRNA and protein expression of ESR1 in boar reproductive tissues, a total of six boars were divided into two groups [Group I (G-I) and Group II (G-II)], where G-I had relatively better sperm quality. ESR1 expression was higher in tissues collected from G-I boars than those of collected from G-II boars, and the difference in mRNA expression was significant (P<0.01) in head of epididymis. The ESR1 protein expression results from western blot coincided with the results of qRT-PCR. The ESR1 protein localization observed a strong staining in the cytoplasm of Sertoli cell in the testis, in the epithelial cells in head and tail of epididymis, in smooth muscle in tail of epididymis, and in the post acrosomal region and tail of the spermatozoa. These results will improve the understanding of the functions of the ESR1 in spermatogenesis within the reproductive tract and will shed light on ESR1 as a candidate in the selection of boar with good sperm quality and fertility.     

Comparison of semen characteristics,sperm freezability and testosterone concentration between Duroc and Yorkshire boars during seasons

This study was carried out to investigate the effects of Duroc and Yorkshire boars and seasons influencing semen characteristics, frozen-thawed sperm viability and serum testosterone concentration. Yorkshire boars produced higher semen volume compared to Duroc boars among seasons. However, sperm concentration did not differ significantly between Duroc and Yorkshire boars among seasons. Sperm motility of frozen-thawed sperm in Yorkshire boars was higher than in Duroc boars in spring and summer. Normal acrosome of frozen-thawed sperm in Yorkshire boars was higher than in Duroc boars in winter. Serum testosterone concentrations in Duroc and Yorkshire boars were higher in spring than in summer, autumn and winter. Serum testosterone concentrations in spring and summer were higher in Yorkshire boars than in Duroc boars. In conclusion, when serum testosterone concentrations were higher in Duroc and Yorkshire boars among seasons, semen volume, sperm concentration and frozen-thawed sperm viability were higher.     

Seminal plasma damages sperm during cryopreservation, but its presence during thawing improves semen quality and conception rates in boars with poor post-thaw semen quality

To determine the effects of seminal plasma during and after cyopreservation on post-thaw sperm functions in semen from poor freezability boars, seminal plasma was removed immediately after collection, and sperm was subjected to cooling and freezing. Removal of seminal plasma did not significantly affect post-thaw sperm motility in good freezability boars; however, in boars with poor freezability, it increased post-thaw motility relative to control sperm cooled with seminal plasma (64.5+/-3.4% vs. 30.9+/-3.1%, P<0.01). Freezing sperm without seminal plasma increased both loss of the acrosome cap (37.5+/-1.6% vs. 18.4+/-2.8%, P<0.01) and expression of a 15 kDa tyrosine-phosphorylated protein (capacitation marker) in thawed sperm relative to controls; the addition of 10% (v/v) seminal plasma to the thawing solution significantly suppressed both changes and increased conception rate to AI (70% vs. 9% in the control group, P<0.05). In conclusion, our novel cryopreservation and thawing method increased the success of AI with frozen-thawed porcine semen, particularly from boars with poor post-thaw semen quality.     

Celestial moderation of tropical seabird behavior

Most animals, including birds, have cyclic life histories and numerous studies generally conducted on captive animals have shown that photoperiod is the main factor influencing this periodicity. Moon cycles can also affect periodic behavior of birds. Few studies have investigated the influence of these environmental cues in natural settings, and particularly in tropical areas where the change in photoperiod is slight and some bird species keep cyclic behaviors. Using miniaturized light sensors, we simultaneously investigated under natural conditions the influence of photoperiod and moon phases on the migration dates and at-sea activity of a tropical seabird species, the Barau's petrel, throughout its annual cycle. Firstly, we found that birds consistently started their pre- and post-breeding migrations at precise dates corresponding in both cases to a day-duration of 12.5 hours, suggesting a strong influence of the photoperiod in the regulation of migration behavior. We also found that mean population arrival dates to the colony changed from year to year and they were influenced by moon phases. Returns at their colonies occurred around the last full moon of the austral winter, suggesting that moon cycle is used by birds to synchronize their arrival. Secondly, variations of day-time activity were sinusoidal and correlated to seasonal changes of daylength. We thus hypothesize that the photoperiod could directly affect the behavior of the birds at sea. Night-time at-sea activity exhibited a clear cycle of 29.2 days, suggesting that nocturnal foraging was highly regulated by moon phase, particularly during the non-breeding season. To our knowledge, this is the first study to document a mixed regulation of the behavior of a wild bird by photoperiod and moon phases throughout its annual cycle.     

Effects of single nucleotide polymorphisms in the 5'-flanking region of heat shock protein 70.2 gene on semen quality in boars

This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5'-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5'-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5'-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season.     

DO PHOTOPERIOD AND TEMPERATURE INFLUENCE THE MOLT CYCLE OF PHOCA VITULINA IN CAPTIVITY?

Photoperiod variations are the principal environmental signals entraining circannual activity in mammals, which is also believed to be influenced by changes in temperature and nutrition. Control of the molt in phocids has not been extensively studied with experimental manipulations of environmental factors, but substantial work indicates that photoperiod has a primary influence on mammalian breeding and furring mechanisms. Studies were under taken to reestablish the molt cycle in five harbor seals ( Phoca vitulina ) previously kept in an enclosed facility with a limited air/water temperature gradient and artificial photoperiod. The seals were exposed to an extended temperature gradient during the first period of study, and no molting was observed. The second period of study was characterized by a natural occurring photoperiod of 8 h 53 min light (L)/15 h 07 min dark (D) and a maximal 15 h 31 min L/8h 29 min D duration, and molting occurred in all individuals. These results suggest a prevalent influence of photoperiod variation on the harbor seal molt.     

Impact of porcine circovirus type 2 (PCV2) vaccination on boar semen quality and quantity using two different vaccines

Porcine circovirus type-2 (PCV2) is widespread in domestic pig populations. It can be shed with boar semen, but the role boars have in epidemiology is still unclear. Vaccinating boars against PCV2 can reduce disease and virus load in semen, but may have unwanted side effects, that is, impairment of spermatogenesis. Therefore, the aim of this study was to investigate the effect and impact of two different PCV2 vaccines on boar semen quality and quantity. Healthy normospermic Large White boars in three groups of 12 each were vaccinated with either Circovac, Ingelvac CircoFLEX, or received NaCl. Eight ejaculates were collected starting 1 week after vaccination and assessed for quantitative traits. In general, sperm quantity and quality parameters did not change due to the vaccination (P > 0.05). Only DNA integrity between the Circovac and control group was P < 0.05 but remained at a low level (<2%). One boar showed clinical signs with body temperature up to 39.9 °C and went off feed. For this animal, a clear relation between vaccination, fever period, and impaired sperm quality could be observed. The results indicate that both vaccines did not have a major impact on sperm quality or quantity. Therefore, vaccination of boars against PCV2 seems to be feasible. However, one boar treated with the oil-based vaccine showed a temporarily impaired semen quality after elevated body temperature after vaccination. Thus, possible systemic reactions and the subsequent impact on sperm quality should be taken into account when choosing a PCV2 vaccine for boars.     

Association study and expression analysis of CD9 as candidate gene for boar sperm quality and fertility traits

Cluster-of-differentiation antigen 9 (CD9) gene expressed in the male germ line stem cells is crucial for sperm-egg fusion, and was therefore selected as candidate gene for boar semen quality. The association of CD9 with boar sperm quality and fertility trait was analyzed using a total of 340 boars both from purebred Pietrain and Pietrain×Hampshire crosses. A single nucleotide polymorphism (g.358A>T) in intron 6 was significantly associated with sperm motility (MOT) (P<0.001), plasma droplet rate (PDR) (P<0.001) and abnormal spermatozoa rate (ASR) (P<0.01). Boars were divided into two groups with group 1 (G-I) boars having a higher SCON and SMOT, lower SVOL (sperm volume) and group 2 (G-II) having a lower SCON and SMOT, higher SVOL. The mRNA and protein expression levels were evaluated in reproductive, non-reproductive tissues and spermatozoa from G-I and G-II animals by using quantitative real-time PCR and western blotting. When both reproductive and non-reproductive tissues were examined, highest mRNA was expressed in prostate gland, then in the body of the epididymis, vas deferens and tail of the epididymis. In case of reproductive tissues, CD9 expression was higher in tissues and spermatozoa collected from G-I boars than those collected from G-II boars. The mRNA expression was significantly different (P<0.05) in body of epididymis from G-I and G-II boars. The CD9 protein expression results from western blot were coincided with the results of qRT-PCR. Moreover, CD9 protein localization in Leydig cells, Sertoli cells, epithelial cells and spermatozoa was remarkable which indicated the important role of CD9 in spermatogenesis process. By using mRNA and protein expression profiles, it could be shown that CD9 plays a crucial role during sperm development, especially within the epididymis where the maturation of the sperm, a key process for the sperm quality and motility takes place. These results will improve the understanding of the functions of the CD9 in spermatogenesis within the reproductive tracts and will shed light on CD9 as a candidate gene in the selection of good sperm quality boars.     

Management and sperm production of boars under differing environmental conditions

The management of boars to ensure good sperm production under differing environmental conditions is a major concern for pig keepers in both tropical countries and countries where there are extreme environmental changes. Such changes create stress in animals and influence the production of spermatozoa. High temperatures during hot summer months may result in lower feed consumption and create stresses that result in the inhibition of spermatogenesis. Although tropical countries do not have a problem with major variations in day length, this can cause problems such as decreased litter size and infertility in other regions of the world. Evaporative cooling systems built into boar accommodation are often used to reduce fluctuations in both temperature and humidity during the hot and humid months seen in tropical countries. The system has become popular in AI boar studs, where it is reported to reduce stress and improve feed consumption. Other management factors, such as housing comfort, social contact, mating conditions and the frequency of mating, are also very important boar management aids that assist good quality semen production; these will be covered briefly in this review. This review will consider primarily those management factors, for example, the management of temperature and humidity using evaporative cooling systems and other techniques that enable AI boar studs to maximize sperm fertility through adjustments to the environment.     

Effects of increased levels of supplemental vitamins during the summer in a commercial artificial insemination boar stud

Heat stress due to increasing extremes in ambient temperature and humidity results in reduced semen quality in boars. This has caused reduced efficiency of the swine industry, requiring more boars to breed the same number of sows. Vitamins such as vitamin C (VC) and E (VE) have been shown to improve semen quality in boars. Recently, vitamin D has been shown to improve semen quality in boars. The purpose of this experiment was to evaluate the effects of increased supplemental vitamins on boar reproduction during the summer season in a commercial boar stud. One hundred and sixty Pig Improvement Company (PIC) terminal line boars (n = 32 per treatment) and 39 maternal, heat-sensitive boars (n = 7 or 8 per treatment) were randomly allocated to treatment and fed a corn and soybean meal-based diet adjusted based on individual boar body condition score. A control (CNT) diet was used that met PIC recommendations for boars. Increased supplementation of specific vitamins was given in the form of a top-dress and consisted of CNT wheat middlings, CNT plus VC (560 mg/day), CNT plus 25-hydroxy vitamin D₃ (VD) (125 µg/day), CNT plus VE (275 mg/day) and CNT plus VC, VD and VE (CDE). The experiment was split into three periods based on maximum daily high temperatures in the barn, where period 1 was weeks 1 to 4, period 2 was weeks 5 to 11 and period 3 was weeks 12 to 14. Semen was collected from boars as needed using the stud’s normal production schedule and was analyzed for sperm quantity and quality characteristics. There were no dietary effects on semen volume, sperm concentration or total sperm production (P ≥ 0.553). Total motility of sperm was not impacted by diet (P = 0.115); although, VC tended (P = 0.064) to have a greater progressive motility than CDE. Percentages of morphologically normal sperm and normal acrosomes were not affected by dietary supplementation (P ≥ 0.157). Period effects were observed for most semen quality parameters, with quality generally becoming reduced over time. The present study demonstrates that increased supplementation of vitamins beyond PIC recommendations was not beneficial for boar reproduction during the summer.     

Influence of photoperiod on the seasonal pattern of secretion of luteinizing hormone and testosterone and on the antler cycle in roe deer (Capreolus capreolus).

Annual variations in concentrations of luteinizing hormone (LH) and testosterone in plasma were analysed in relation to the antler cycle in six adult male roe deer exposed to a natural photoperiod (latitude 46 degrees 10'N) and in four adult males maintained in a constant short-day photoperiod (8 h light: 16 h dark) for a year, from the winter solstice at which time both groups of animals had antlers in velvet. The animals were sampled, every 15 min for 2 or 4 h at intervals of one month for a year. Under both natural and experimental conditions, LH concentrations were high from January to March, but in the experimental conditions they decreased between April and May-June, whereas in the natural conditions they increased. Plasma LH concentration was lowest between July and November in animals under natural photoperiod, whereas under 8 h light:16 h dark photoperiod a second increase in plasma LH occurred between August and September. Between March and August, concentrations of plasma testosterone increased under natural photoperiod, whereas under experimental photoperiod there was a biphasic pattern of plasma testosterone with peaks between February and May and between September and November. Under natural photoperiod, antlers were cast in November, 369 +/- 6 days after the previous antlers were cast. Under experimental photoperiod, antlers were cast after 193 +/- 10 days, and a new set developed. The sexual cycle of the male appears to be initiated by an endogenous rhythm in winter and is then maintained by hormonal changes resulting from increasing photoperiod in spring.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of plasma membrane and chromatin structure of sperm from transgenic and non-transgenic boars

The aim of this study was to determine the apoptotic changes and chromatin damage in non-transgenic and transgenic boars carrying the human α1,2-fucosyltransferase gene. Five ejaculates were collected from six transgenic (TG) and six non-transgenic (NTG) boars. Five ejaculates were collected from six transgenic (TG) and six non-transgenic (NTG) boars both crossbreds of Polish Landrace and Large White. Two fluorescence methods were employed to measure apoptosis: an assay to assess the early changes in sperm membrane integrity using fluorophore YO-PRO-1 and an assay for phosphatidylserine (PS) translocation across the plasma membrane using fluorescein-labeled Annexin-V. The chromatin damage was assessed based on the sperm chromatin structure assay method. No significant differences in the proportion of all detected subpopulations of spermatozoa were found between TG and NTG boars. Similarly, the analysis of the chromatin structure revealed no statistical differences in the sperm chromatin damage between TG and NTG boars. In conclusion, the presence of the human α1,2-fucosyltransferase gene in the genome of TG boars did not cause any spermatogenesis process disturbances leading to the increased production of apoptotic spermatozoa. Moreover, the low level of sperm with damaged chromatin in TG boars confirms the high stability of the spermatogenesis process in the TG boars analyzed.     

Evidence of seasonal variation in bioluminescence of Amphipholis squamata (Ophiuroidea, Echinodermata): effects of environmental factors

The bioluminescence of Amphipholis squamata was assessed from freshly collected individuals for 16 successive months, and from individuals maintained in the laboratory under various experimental conditions of salinity, temperature and photoperiodic regime. Field investigations showed that bioluminescence intensity and kinetics varied seasonally, with the light produced being brighter and faster in winter and summer. The seasonal variation was not correlated with changes of ambient salinity. However, it was correlated with changes in temperature, the luminescence being brighter and faster in coldest and warmest seasons, and with the changes of photoperiod, the luminescence being brighter and faster in seasons with shortest and longest day length. Laboratory investigations also demonstrated that luminescence was not affected by salinity conditions. Conversely, luminescence was affected by temperature, the light production being brighter and faster in warmer conditions (in agreement with field observations) and dimmer and slower in colder conditions (in disagreement with field observations). Light production was also affected by photoperiod since experimental changes of natural light:dark regime caused the bioluminescence to decrease. Considering that photoperiod guides the biology of A. squamata and that reproduction takes place during coldest months in the species, an endogenous factor of neurophysiological nature linked to the ophiuroid reproductive cycle is proposed to induce the luminescence to peak in winter. This was confirmed by the fact that seasonal variation of luminescence was different between adult and juveniles, the latter showing no winter peak of luminescence. It is suggested that the luminescence normally associated with defense could also be part of an intraspecific visual signal related to individuals aggregating for reproduction during winter.