In this study, we analysed genetic diversity, population structure and inbreeding in the Lipica Stud Farm population by integrating pedigree records, microsatellite (STR) and genome-wide SNP data generated using the GGP Equine 70K BeadChip. The dataset comprised 233 horses from the Lipica Stud Farm, which served as the reference population for comparisons of diversity estimates based on pedigree-, STR- and SNP data. The STR data were originally generated for routine parentage verification and were included here to compare inbreeding estimates based on pedigree, STR and genome-wide SNP data. Pedigrees of the analysed horses were traced back to the 18th century, with the longest ancestral path spanning 35 generations. The mean pedigree inbreeding coefficient in the reference population was 11.55%, while ancestral inbreeding coefficients ranged from 5.93% to 15.42%. Microsatellite analyses revealed an average observed heterozygosity (Ho) of 0.68 and a mean of 5.9 alleles per locus, with STR-based inbreeding (FSTR) ranging from 0.10 to 0.15. However, genomic inbreeding estimated from runs of homozygosity (FROH) varied between 0.09 and 0.28, with an average of 0.16. Selection signature analysis identified several putative candidate regions, whereas integrated haplotype score (iHS) analysis highlighted three candidate protein-coding genes (ZNF114, DENND5A, and TENM4). The ROH islands contained 24 genes previously associated with pigmentation, reproduction, muscle function, and other biologically relevant traits in horses. These results provide a comprehensive genomic characterisation of the Lipica Stud Farm population and offer important insights into genetic diversity and inbreeding patterns in the Lipizzan breed.

IntroductionThe aim of our study was to measure fecal glucocorticoid metabolite (FGM) concentrations in captive and free-ranging male and female mountain gazelles (Gazella gazella) during their circannual cycle. In addition, FGM concentrations were used to track the intensity of the adrenocortical response in mountain gazelles during the same period.MethodsFecal samples were collected from the ground in the Hatay Mountain Gazelle Wildlife Development Area in the Hatay Province of Türkiye (36°32’ N, 36°32′ E) in each season of the year (December, April, July, September). The sex of the animals was determined by detecting the SRY gene of the Y chromosome in DNA isolated from the fecal samples. FGM was extracted from dried fecal samples with methanol, and its concentration was measured using a previously partially validated ELISA.Results and discussionThe results indicate that season is the most important factor explaining the variability in FGM concentrations in mountain gazelles. In animals of both sexes, the highest concentrations of FGM were observed in September. The values were significantly higher in the captive population, perhaps due to unpredictable stress. In July, FGM concentrations were low in both populations. As a result of the overall analysis across seasons, the comparison of FGM concentrations between captive and free-ranging animals revealed higher concentrations in captive animals only in September but not in other seasons, although higher concentrations have been previously reported for several wild captive species. Due to predation risk, the presence of offspring can be considered a critical point in the biological cycle for the welfare of free-ranging mountain gazelles, as suggested by the higher FGM concentrations in the free-ranging population in July. The high number of visitors could be a challenge for mountain gazelles in captivity, as indicated by higher FGM concentrations during September. Sex had no effect on the FGM concentrations of either population.

Within the Bosnian Mountain Horse Registry (BMH), some specific coat colours are permitted. Accurate determination of coat colours can be challenging as there are variations in coat colour shades and several dun dilution variants occur. The previously found single nucleotide polymorphisms (SNPs) within two coat colour loci, T-box 3 (TBX3) and Agouti Signalling Protein (ASIP), were genotyped in 313 BMH individuals. The obtained genotypes were then compared to the predicted phenotypes by using the observed coat colour types from the International Association of Bosnian Mountain Horse Breeders (IABMHB) database. It was found that the dark bay and black coat colours were the most representative coat colours both phenotypically and genotypically. The frequency of the dominant Dun (D) dilution allele is (0.09), and this frequency is higher than the previously predicted frequency recorded in the available BMH registers, as also demonstrated. Among the identified alleles, there was a discrepancy or inconsistency between the predicted coat colour based on genotypes and the observed coat colour in 73 horses (23%). The most frequent error concerned the misclassification of horses with genotypes aa and Aa at the ASIP gene, non-dun1/non-dun1 (nd1/nd1) and non-dun2/non-dun1 (nd1/nd2) at the TBX3 gene, which can be associated with the occurrence of slight dilution phenotypes in these individuals. In contrast to the Konik and Hucul breeds, no homozygosity of the D allele was found in the BMH. The D allele can be easily overlooked or not recognised in different phenotypic groups, such as dark bay and black horses. Therefore, the hypothesis that Dun dilution effects itself is not as strongly epistatic in the BMH as described in other horse breeds. This could be the result of an additional genetic modifier suppressing the phenotypic effect of the D allele. It also suggests that there has been a persistent selection pressure in favour of dark base colours, which may have contributed to the observed differences in BMH. Finally, a significant proportion (35%) of BMH individuals with genetically black coat colour were officially classified as dark bay. We hypothesise that the difficulty in visually distinguishing these two phenotypes is due to an independent locus upstream of the ASIP gene. This locus was recently identified as a factor that darkens the typical pigmentation in dark bay horses. The results of the study confirm the importance of molecular testing in accurately determining the coat colour of horses. This would help to avoid errors in coat colour descriptions in official breeding records and provide valuable information for selective breeding programmes aimed at producing specific and desired coat colours. Variabilnost genov ASIP in DUN, odgovornih za barvo dlake pri bosanskem planinskem konju Določanje barv dlake pri bosanskem planinskem konju (BPK) je lahko izziv, ker obstajajo razlike v barvnih odtenkih dlake in več oblik redčenja barve dlake (plavci). Pri 313 konjih pasme BPK smo genotipizirali polimorfizme posameznih nukleotidov (SNP) znotraj dveh lokusov za barvo dlake T-box 3 (TBX3) in polimorfizma 11-bp indel znotraj Agouti signalnega proteina (ASIP). Posamezne genotipe smo nato primerjali z vpisanimi fenotipi barv dlake iz baze podatkov MZRBPK (Mednarodno združenje rejcev bosanskega planinskega konja). Ugotovljeno je bilo, da sta bili temna rjava in črna najbolj reprezentativni barvi dlake pri BPK. Pogostnost prevladujočega alela za redčenje Dun (D) v študiji je višja (0,09) od predhodno zabeležene v razpoložljivem registru BPK. Med ugotovljenimi aleli je prišlo do neskladja ali nedoslednosti med predvideno barvo dlake na podlagi genotipov in opazovano barvo dlake pri 73 konjih (23%). Najpogostejša napaka se je nanašala na napačno razvrstitev konjev z genotipoma aa in Aa v genu ASIP, non-dun1/non-dun1 (nd1/nd1) in non-dun1/non-dun2 (nd1/nd2) pri genu TBX3, kar je lahko povezano s pojavom redčenja barve dlake pri teh fenotipih.V nasprotju s pasmami Konik in Hucul pri BPK ni bila ugotovljena homozigotnost alela D. Alel D je mogoče zlahka spregledati ali ga ne prepoznati v različnih fenotipskih skupinah, kot so temni rjavci in vranci. Zato hipoteza, da učinki redčenja Dun (plavci) pri BPK sami po sebi niso tako močno epistatični, kot je to opisano pri drugih pasmah konj. Rezultati študije potrjujejo pomen molekularnega testiranja pri natančnem določanju barve dlake konj. To bi pripomoglo k preprečevanju napak pri opisih barve dlak v uradnih rejskih evidencah in pomembna informacija pri selekciji na posebne in želene barve dlake pri konjih. Ključne besede: barva dlake konj; dun redčenje barve dlake; polimorfizem DNK; frekvenca alelov; frekvenca genotipa; bosanski planinski konj

This study assessed the suitability of the complementarity-determining region 2 (CDR2) of the nanobody (Nb) as a template for the derivation of nanobody-derived peptides (NDPs) targeting active-state β2-adrenergic receptor (β2AR) conformation. Sequences of conformationally selective Nbs favoring the agonist-occupied β2AR were initially analyzed by the informational spectrum method (ISM). The derived NDPs in complex with β2AR were subjected to protein–peptide docking, molecular dynamics (MD) simulations, and metadynamics-based free-energy binding calculations. Computational analyses identified a 25-amino-acid-long CDR2-NDP of Nb71, designated P4, which exhibited the following binding free-energy for the formation of the β2AR:P4 complex (ΔG = −6.8 ± 0.8 kcal/mol or a Ki = 16.5 μM at 310 K) and mapped the β2AR:P4 amino acid interaction network. In vitro characterization showed that P4 (i) can cross the plasma membrane, (ii) reduces the maximum isoproterenol-induced cAMP level by approximately 40% and the isoproterenol potency by up to 20-fold at micromolar concentration, (iii) has a very low affinity to interact with unstimulated β2AR in the cAMP assay, and (iv) cannot reduce the efficacy and potency of the isoproterenol-mediated β2AR/β-arrestin-2 interaction in the BRET2-based recruitment assay. In summary, the CDR2-NDP, P4, binds preferentially to agonist-activated β2AR and disrupts Gαs-mediated signaling.

The genetic background of roan coat color has been investigated by multiple authors in the breeds Belgian draught horse, Shetlandpony, Gotlandpony, Noriker, Murgese, Slovenian Coldblood, Quarter Horse and Icelandic Horse. However, the causal mutation for this color variant could not be detected yet. In this study we genotyped five associated variants in the KIT gene for a sample of 37 roan and 23 non-roan horses from the breeds Noriker, Murgese, Quarter Horse, Welsh Pony, Posavina, Shetlandpony and Icelandic horse, in order to verify and compare them to a newly published KIT variant for the Icelandic horse. The results propose, that the association of the SNP in Intron 17 (ECA3:g.79,543,439A > G) with roan coat color is complete in the Noriker breed and breeds that are genealogically related to it (Slovenian Coldblood, Murgese, Belgian draught horse, Posavina horse). For the Icelandic horse sample, it was shown, that the KIT variant in intron 1 was not linked to the remaining four loci in intron 17, exon 19 and intron 20 of KIT. In the sample of Shetlandponies no variation among genotypes and no association was observed between roan and non-roan horses. The for the Icelandic horse newly associated KIT variant in intron 1 supports the hypothesis of allelic heterogeneity of the roan locus reported by previous studies. The complete sequencing of the KIT region and population specific association analyses in horse breeds of Nordic origin with replication analyses in Warmblooded horse breeds should be able to solve this question of allelic heterogeneity.

Different approaches and classification systems have been established to describe equine coat colour, which varies between breeds and countries. In the present study, we first characterised the coat colour variability in the Slovenian Posavje Horse applying colour spectrophotometry following the CIE L*a*b system. As derived from the classification system of Sponenberg (light bay, bay, mahogany bay, brown and seal brown), the phenotype categories could be confirmed by spectrophotometric data. Furthermore, L*a*b values revealed comparable high phenotypic variability of bay coat colour in the Posavje breed, and the darker shades of bay coat colour were associated with the ASIP and MC1R genotype combination A/a E/E. CIE L*a*b colour spectrophotometry represents an effective tool to characterise and quantify coat colour in horses, especially in chestnut horses, for which the underlying genetic background of coat colour variation remains unknown.Key words: Posavje Horse; MC1R; ASIP; coat colour; spectrophotometry; CIE L*a*b KARAKTERIZACIJA BARVE DLAKE PRI POSAVSKEM KONJU Izvleček: Za opis barv konj se uporabljajo različni pristopi in klasifikacijski sistemi, ki se razlikujejo med posameznimi pasmami in državami. V raziskavi smo najprej opredelili različne barve dlake pri posavskem konju z metodo barvne spektrofotometrije po sistemu CIE L*a*b*. Fenotipsko razdelitev barv dlake po Sponenbergu (light bay/svetli rjavec, bay/rjavec, mahogany bay/kostanjev, brown/temni rjavec and seal brown/črnkast rjavec) smo potrdili s spektrofotometričnimi podatki. Vrednosti L*a*b so pri posavskem konju pokazale primerljivo visoko fenotipsko variabilnost rjave barve, pri tem so bili temnejši odtenki povezani z ASIP in MC1R kombinacijo genotipa A/a E/E. Barvna spektrofotometrija po sistemu CIE L*a*b predstavlja učinkovito orodje za kvalitativno in kvantitativno opredelitev/določanje barv pri konjih, zlasti pri lisjakih, pri katerih še vedno ni znana genska osnova variabilnosti v barvi dlake.Ključne besede: posavski konj; MC1R; ASIP; barva dlake; spektrofotometrija; CIE L*a*b

a loose/broken stalagmite containing small fragments of cemented bones were collected from the Postojna Cave to investigate whether deoxyribonucleic acid (DNA) can be determined. The study is complemented by the Fourier-transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) analysis in order to determine the alteration of the bones and to test whether this analysis can be used as an indicator of possible DNA preservation. In addition, geochemical analyses were conducted in order to determine whether the associated flowstone/stalagmite is suitable for elucidating the timing of bone thanatocoenosis and further palaeoenvironmental analyses. The organic matter (collagen) is poorly preserved. However, we succeeded in amplifying a 94 bp long fragment of the cytochrome b (Cyt b) gene of mitochondrial DNA (mtDNA) in polymerase chain reaction (PCR) for one sample, and in sequencing the amto that of the Cyt b of the cave bear (Ursus deningeri or Ursus spelaeus sensu lato). The uranium-thorium dating of the speleothem covering the bones revealed its thanatocoenosis occurred prior to 55 ka, most likely in the late marine isotope stage 4 or early marine isotope stage 3. High porosity and recrystallisation of the flowstone/stalagmite at this part of the cave prevent high-resolution palaeoclimatic interpretation; however, low-resolution stable isotope geochemistry suggests a steppe-like environment during the subsequent growth of the speleothem.

Intensive artificial and natural selection have shaped substantial variation among European horse breeds. Whereas most equine selection signature studies employ divergent genetic population structures in order to derive specific inter-breed targets of selection, we screened a total of 1476 horses originating from 12 breeds for the loss of genetic diversity by runs of homozygosity (ROH) utilizing a 670,000 single nucleotide polymorphism (SNP) genotyping array. Overlapping homozygous regions (ROH islands) indicating signatures of selection were identified by breed and similarities/dissimilarities between populations were evaluated. In the entire dataset, 180 ROH islands were identified, whilst 100 islands were breed specific, all other overlapped in 36 genomic regions with at least one ROH island of another breed. Furthermore, two ROH hot spots were determined at horse chromosome 3 (ECA3) and ECA11. Besides the confirmation of previously documented target genes involved in selection for coat color (MC1R, STX17, ASIP), body size (LCORL/NCAPG, ZFAT, LASP1, HMGA2), racing ability (PPARGC1A), behavioral traits (GRIN2B, NTM/OPCML) and gait patterns (DMRT3), several putative target genes related to embryonic morphogenesis (HOXB), energy metabolism (IGFBP-1, IGFBP-3), hair follicle morphogenesis (KRT25, KRT27, INTU) and autophagy (RALB) were highlighted. Furthermore, genes were pinpointed which might be involved in environmental adaptation of specific habitats (UVSSA, STXBP4, COX11, HLF, MMD).

This study aimed to compare age-dependent changes in the relative expression of genes encoding myosin heavy chain (MyHC) isoforms and selected lipid metabolism-related genes in the longissimus dorsi muscle of wild pigs (WPs) and domestic pigs (DPs). Muscles sampled from postnatal day one as well as three-week-old and two-year-old animals were used in quantitative polymerase chain reaction (qPCR) assays, histological evaluations of succinate dehydrogenase (SDH) activity, and intra-myofiber lipid (IMFL) assessment. Expression of the MyHC isoforms displayed the most extensive age- and breed-dependent changes within the first three postnatal weeks. The MyHCembry level decreased significantly faster in the WPs than in the DPs. The relative MyHC-I and -IIa expression was significantly higher in the WPs, and MyHC-IIb was substantially higher in the DPs. The differences in MyHC expression corroborated the number of SDH-positive myofibers and IMFLs. Expression of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), peroxisome proliferator-activated receptor gamma (PPARγ) and lipoprotein lipase (LPL) genes displayed only age-related variations. In summary, the evidence is provided for accelerated postnatal myofiber transformation directed towards oxidative myofibers in WPs. The SDH activity/staining intensity largely reflected the expression of MyHCs, and not genes involved in lipid uptake and utilization.

Long consecutive homozygous genotype segments, runs of homozygosity (ROH), are a result of parents transmitting identical haplotypes, which can be used to estimate autozygosity. Based on 612K single-nucleotide polymorphisms, we computed three ROH parameters (genome length covered by ROH, S-ROH; number of ROH, N-ROH; and autozygosity, F-ROH) to investigate different scenarios in contemporary horse breeding: limited census (Bosnian mountain horse), conservation breeding (Posavje horse), and selection within closed studbook (Haflinger). The ROH parameters revealed well-defined differences between breeds. S-ROH was highest in the Bosnian mountain horse with 296.32 Mb, followed by the Haflinger sample (S-ROH = 270.35 Mb) and the Posavje sample with 192.68 Mb. The highest number of ROH segments (ROHs) was observed within the Haflinger sample followed by the Posavje sample. F-ROH ranged at a population level from 8.59% in Posavje, over the Haflinger (mean F-ROH = 12.05%) to 13.21% in the Bosnian mountain horse breed. Bottlenecks were detected for Bosnian mountain horse and Haflinger, whereas for the Posavje, a positive effect of the conservation breeding program was documented. Investigating the distribution of ROHs across the genome, we detected four common ROH islands on equine chromosomes ECA 6, ECA 11, and ECA 17, which were present in all breeds. On breed level, the Bosnian mountain horses contained 10, the Posavje, four, and the Haflinger, 11 distinct ROH islands (containing the MC1R locus on ECA 3). With this analysis, we were able to compare genomic levels of inbreeding between breeds differing in management, pedigree completeness, and genes under selection. (C) 2018 Elsevier Inc. All rights reserved.

Sheep with valine (V) at codon 136 and glutamine (Q) at codon 171 of the prion protein gene ( Prnp) are highly susceptible to classical scrapie, whereas phenylalanine (F) at codon 141 and histidine (H) at codon 154 play a major role in the susceptibility to atypical scrapie. A TaqMan real-time PCR assay was developed to determine Prnp alleles at codons 136, 141, 154, and 171 and used in classical scrapie eradication and breeding programs adopted in Slovenia. The frequency of the most resistant genotypes ARR/ARR and ARR/ARQ increased significantly in tested animals ( n = 35,138) from 6.7 and 27.1% of the tested sheep in 2006 to 12.1 and 32.4%, respectively, in 2015. Frequencies of more susceptible genotypes ARQ/ARQ and ARQ/VRQ decreased significantly from 36.4 and 3.5% in 2006 to 31.1 and 1.8%, respectively, in 2015. The most susceptible genotype VRQ/VRQ was detected in <0.5% of tested sheep. Frequencies of alleles AFRQ and AHQ affecting the susceptibility to atypical scrapie did not change significantly. The developed assay was suitable for genotyping on a small-to-medium throughput scale and was successfully used in classical scrapie eradication, as well as for the selection of classical scrapie–resistant sheep within breeding programs in Slovenia.

Atypical scrapie is a form of transmissible spongiform encephalopathy (TSE). It is observed in most European countries and represents a growing proportion of detected scrapie cases in sheep. Ovine atypical scrapie was established in Slovenia for the first time in 2010 after introduction of the test that was sensitive enough to detect the form of prions characteristic for atypical scrapie. From the beginning of 2010 to the end of March 2016 we tested for scrapie 8633 sheep and confirmed 10 cases of atypical scrapie. Susceptibility to classical and atypical form of scrapie is at least partly genetically determined. It is known that sheep with the prion protein gene (Prnp) genotype ARR/ARR are the most resistant to the development of classical form of scrapie, the sheep with the genotype VRQ/VRQ are the most susceptible. Conversely, atypical scrapie often occurs in sheep with ARR allele and rarely in sheep carrying the VRQ allele. In addition, development of the disease is significantly affected by the amino acid at position 141 of the prion protein (fenilalanin or leucin). Comparison of Prnp genotypes of sheep with atypical scrapie to genotypes of 1,680 randomly selected dead sheep showed that atypical scrapie does not occur in sheep carrying alleles VLRQ and ALRH. It was detected in sheep with allele AFRQ, although in Slovenia proportion of ewes with this allele is small (1.14% of the sample of sheep) and in animals with allele ALHQ. Only a small proportion of diseased sheep had allele ALRR and ALRQ. Allele ALHQ in Slovenia occurs in 6.5% of sheep, so we can expect that the atypical scrapie would occur in our sheep population.

On two successive nights a flock of sheep living in the fenced meadow was attacked by an unidentified attacker(s) and all of thirty-five sheep were killed or badly injured. Deadly injures were mainly located on the heads of the sheep because of the long protective woollen fleece on the sheep bodies. Four heads of the killed animals were delivered to the laboratory five days after the attack to look for traces of the suspect attacker. Traces of saliva were looked for specially at the edges of the lacerations. From the samples of the glued hair near the lacerations on sheep heads DNA was isolated using QIAamp DNA Investigator kit from Qiagen. Canine specific short tandem repeats (STRs) were amplified in the PCR reaction using the kit Canine Genotypes, Panel 1.1 (Finnzymes Diagnostics) that is designed for canine genotyping, identification, parentage testing and breed testing. Separation and visualisation of the obtained fluorescently labelled PCR products was performed by capillary electrophoresis on the ABI PRISM 310 Genetic Analyser (Applied Biosystems). In one sample the DNA profile on 11 STR loci was determined. The obtained STR profile could belong to the suspect attacker on the flock from the canidae family.

Polymelia or supernumerary ectopic limb (SEL) is a congenital anomaly of musculoskeletal system that can be found at different animal body regions. This malformation usually occurs solitarily or rarely together with other developmental/inheritable anomalies. In the case of a newborn female calf (crossbred with Cika cattle) anal atresia together with SEL attached to the perineal region was observed. We performed surgical reconstructionof the anal canal and the SEL removal following pathoanatomical diagnosis and genetic test (microsatellite profiles). The SEL was underdeveloped, partly deformed and not functional. The hip bone, femur, tibia and fibula were extremely reduced while the tarsals, metatarsals and phalanges were developed almost normally. Around the hip bone a large amount of fat tissue was present while the limb was devoid of muscular tissue. Comparisons between microsatellite profiles showed complete similarity of alleles therefore the SEL most likely belongs to the calf. The coincidence of polymelia and anal atresia in the same animal points out the inheritance of abnormal genes. The operation of anal atresia enabled the animal normal life and the successful removal of the SEL improved her wellbeing and appearance. The present paper is the first report of polymelia in a cattle calf in Slovenia.

Polycystic kidney disease (PKD) is an inherited autosomal kidney disease which is most commonly identified in Persian and Persian related cats. Positive cats have multiple cysts of various sizes that occur in the renal cortex and medulla and occasionally in other abdominal organs. PKD often leads to renal failure which occurs from mid to late in life. Renal cysts can be diagnosed ultrasonographically after 7 weeks of age by an experienced ultrasonographer and a high resolution machine. However, ultrasonography is now being replaced by genetic screening. A total of 340 cats of variable breeds aged from 5 months to 18 years were ultrasonographically examined in the past 7 years at the University Veterinary Small Animal Clinic. Of these, 13.8% were PKD positive with very high prevalence in Persian cats (36%). There was no sex predilection identified. The C>A transversion at position 3284 on exon 29 of PKD1 gene, resulting in a stop mutation has been identified in the heterozygous state in eight affected cats examined (Persian breed). All heterozygous cats were also ultrasonographically positive.

The multidrug-resistance 1 (MDR1) transport protein plays an important protective role at blood-tissue barriers by limiting the entry of MDR1 protein substrates to brain, testis, fetus and other tissues. For subpopulation of Collies and related dog breeds increased susceptibility to neurotoxic side effects of several drugs including ivermectin, moxidectin and loperamide was detected. It was demonstrated that in ivermectin susceptible dogs the deletion mutation in MDR1 gene produces a frame shift resulting in the production of severly truncated non-functional MDR1 protein. In order to evaluate the occurrence and frequency of the mutated mdr1-1∆ allele in the population of Australian Shepherds in Slovenia we have screened 10 dogs representing approximately one third of the Slovenian population. The results of our study indicate very high frequency of mdr1-1∆ allele (70%) in Australian Shepherds in Slovenia. In 40% of studied population homozygous mutated genotype was determined. Considering the important role of MDR1 protein in drug disposition and blood-brain barrier protection, testing of the MDR1 genotypes and MDR1 genotype-based breeding programs are recommended for improving the safety of drug therapy with MDR1 protein substrates in Australian Shepherds.

Lanosterol 14α-demethylase (CYP51) is a microsomal cytochrome P450 enzyme involved in the postsqualene cholesterol biosynthetic pathway. CYP51 removes 14α-methyl group from lanosterol], forming FF-MAS (folicular fluid meiosis activating sterol) which accumulates in gonads. The goal of our study is to determine the expression of CYP51 protein in the male gonad. Using electron microscopic immunogold techniques, CYP51 is localised on inner and outer acrosomal membranes of male germ cells, the round and elongated spermatids. Significance of CYP51 localization on the acrosome which is a Golgi-derived organelle is not known, but we propose that CYP51-formed FF-MAS can function as a signalling sterol during fertilisation.