Birth of kids after artificial insemination with sex-sorted, frozen-thawed goat spermatozoa

Successful sex-sorting of goat spermatozoa and subsequent birth of pre-sexed kids have yet to be reported. As such, a series of experiments were conducted to develop protocols for sperm-sorting (using a modified flow cytometer, MoFlo SX(®) ) and cryopreservation of goat spermatozoa. Saanen goat spermatozoa (n = 2 males) were (i) collected into Salamon's or Tris catch media post-sorting and (ii) frozen in Tris-citrate-glucose media supplemented with 5, 10 or 20% egg yolk in (iii) 0.25 ml pellets on dry ice or 0.25 ml straws in a controlled-rate freezer. Post-sort and post-thaw sperm quality were assessed by motility (CASA), viability and acrosome integrity (PI/FITC-PNA). Sex-sorted goat spermatozoa frozen in pellets displayed significantly higher post-thaw motility and viability than spermatozoa frozen in straws. Catch media and differing egg yolk concentration had no effect on the sperm parameters tested. The in vitro and in vivo fertility of sex-sorted goat spermatozoa produced with this optimum protocol were then tested by means of a heterologous ova binding assay and intrauterine artificial insemination of Saanen goat does, respectively. Sex-sorted goat spermatozoa bound to sheep ova zona pellucidae in similar numbers (p > 0.05) to non-sorted goat spermatozoa, non-sorted ram spermatozoa and sex-sorted ram spermatozoa. Following intrauterine artificial insemination with sex-sorted spermatozoa, 38% (5/13) of does kidded with 83% (3/5) of kids being of the expected sex. Does inseminated with non-sorted spermatozoa achieved a 50% (3/6) kidding rate and a sex ratio of 3 : 1 (F : M). This study demonstrates for the first time that goat spermatozoa can be sex-sorted by flow cytometry, successfully frozen and used to produce pre-sexed kids.

Flow-sorted ram spermatozoa are highly susceptible to hydrogen peroxide damage but are protected by seminal plasma and catalase

To determine whether flow sorting increased the susceptibility of spermatozoa to reactive oxygen species (ROS), ram semen was either diluted with Tris medium (100 × 106 spermatozoa mL–1; D) or highly diluted (106 spermatozoa mL–1) before being centrifuged (DC) at 750g for 7.5 min at 21°C or flow-sorted (S) before cryopreservation. Thawed spermatozoa were resuspended in graded concentrations of hydrogen peroxide to induce oxidative stress. In Experiment 1, following exposure to 30 or 45 μM hydrogen peroxide (H2O2), the total motility (%) of DC (41.0 ± 7.3 or 25.7 ± 6.7, respectively) and S spermatozoa (33.8 ± 6.3 or 20.1 ± 6.3, respectively) was lower (P < 0.001) than that of D spermatozoa (58.7 ± 5.6 or 44.5 ± 6.7, respectively). In Experiment 2, supplementation of samples containing H2O2 with catalase (150 IU mL–1) or seminal plasma proteins (4 mg protein per 108 spermatozoa) negated oxidative stress, resulting in comparable values to samples receiving no H2O2in terms of the proportion of spermatozoa with stable plasmalemma (as determined using merocyanine-540 and Yo-Pro-1) in the D and S groups, the proportion of viable, acrosome-intact spermatozoa (as determined by fluorescein isothiocyanate and propidium iodide staining) in the D group and the motility of control (undiluted) and S spermatozoa. Neither H2O2 nor sperm type (i.e. D, DC or S) had any effect on intracellular concentrations of ROS. These results show that flow sorting increases the susceptibility of spermatozoa to ROS, but the inclusion of anti-oxidants or seminal plasma as part of the sorting protocol improves resistance to oxidative stress.

Birth of offspring after artificial insemination of heifers with frozen-thawed, sex-sorted, re-frozen-thawed bull sperm

Two field trials were conducted to determine the fertilising capacity of (i) frozen-thawed, sex-sorted re-frozen-thawed (FSF) dairy bull sperm inseminated close to the time of ovulation, (ii) FSF sperm following large dose insemination, and frozen-thawed, sex-sorted (FS) sperm inseminated within 12h after sorting. In Trial 1, 24 heifers in synchronised oestrus were observed for standing heat over a 30-min period once every 3h. Upon observation of standing heat, the size of the pre-ovulatory follicle was tracked by ultrasound every 6h until ovulation was judged to be imminent. Heifers were inseminated with 4 x 10(6) X-bearing FSF or Control sperm within 6h of ovulation. Ovaries were scanned 6h after AI to ensure ovulation had occurred. All 24 heifers displayed standing oestrus and 20 of these subsequently ovulated. The mean length of standing oestrus was 16.8+/-0.4h and ovulation occurred 27.6+/-1.1h after the onset of standing heat from a pre-ovulatory follicle with a diameter of 16.1+/-0.3mm. All 12 heifers that received FSF sperm returned to oestrus<26d after AI. Of 8 heifers that received Control sperm, 6 (75%) were confirmed pregnant by ultrasound 7 wk after AI, confirming that the method of AI and herd fertility were sound. In Trial 2 the number of sperm inseminated and the effect of eliminating the post-sort cryopreservation step were investigated. Heifers (n=21) were synchronised for oestrus, and inseminated 24h after the onset of standing oestrus with 10 x 10(6) X-bearing FSF, 4 x 10(6) X-bearing FS, or 10 x 10(6) non-sorted frozen-thawed (Control) sperm. Heifers were observed for return to oestrus from 21d, and diagnosed for pregnancy 7 wk after AI. Of the 7 heifers that received FSF sperm, one was confirmed pregnant (14.3%) and delivered a female calf. Four heifers inseminated with control sperm became pregnant and calved, but no pregnancies were obtained using FS sperm. The birth of a calf following AI with FSF sperm demonstrates the potential of sorting from frozen-thawed semen, and with further work, may be a promising technique that will give producers access to sexed sperm from a greater range of bulls.

INSL3/RXFP2 signaling in testicular descent

Mutations of the insulin-like peptide 3 (INSL3) hormone or its receptor, RXFP2, cause intraabdominal cryptorchidism in male mice. Specific RXFP2 expression in mouse gubernacula was detected at embryonic day 14.5 and markedly increased after birth in the developing cremaster muscle, as well as in the epididymis and testicular Leydig and germ cells. INSL3 treatment stimulated cell proliferation of embryonic gubernacular and Leydig cells, implicating active INSL3-mediated signaling. The transcription factor SOX9, a known male sex determination factor, upregulated the activity of the RXFP2 promoter. INSL3 is sufficient to direct the first transabdominal phase of testicular descent in the absence of hypothalamic-pituitary-gonadal axis signaling or Hoxa10, although these factors are important for inguinoscrotal testicular descent. Similarly, conditional ablation of the androgen receptor gene in gubernacular cells resulted in disruption of inguinoscrotal descent. We performed mutation screening of INSL3 and RXFP2 in human patients with cryptorchidism and control subjects from different populations in Europe and the USA. Several missense mutations were described in both the INSL3 and RXFP2 genes. A novel V39G INSL3 mutation in a patient with cryptorchidism was identified; however, the functional analysis of the mutant peptide did not reveal compromised function. In more than 2000 patients and controls analyzed to date, the T222P RXFP2 mutation is the only one strongly associated with the mutant phenotype. The T222P mutant receptor, when transfected into 293T cells, had severely decreased cell membrane expression, providing the basis for the functional deficiency of this mutation.

Recent advances in boar semen cryopreservation

Since 35 years ago boar semen has been frozen and used for artificial insemination (AI). However, fertility of cryopreserved porcine sperm has consistently been low as boar sperm are more sensitive to cellular stress imposed by changing osmotic balance, oxidative stress, low-temperature exposure, cryo-protectant intoxication etc. and are less able to compensate for these deficiencies at commercially applicable dosages. Additionally, differences in sperm freezability among individuals are well known. Here we review current advances on tests to screen sperm quality post-thaw, on ways of diminishing individual boar effects, on improvement of cryo-protection by novel extender components, on packaging and freezing protocols and freezing and thawing methods, and on the handling of sexed boar sperm. Major advances have been registered, which have improved cryo-survival and the capacity to process boar semen for commercial AI.

Early pregnancy loss in sows after low dose, deep uterine artificial insemination with sex-sorted, frozen–thawed sperm

Recent developments in reproductive technologies have enabled the production of piglets of a predetermined sex via non-surgical, low dose artificial insemination. The practical application of sex-sorting technology to the pig is made challenging by the large numbers of sperm required for successful insemination of sows. One way of overcoming the time required for sex-sorting may be to create a bank of cryopreserved, sex-sorted sperm, thus making available appropriate doses as sows require insemination. To date, little success has been achieved with non-surgical inseminations of sex-sorted boar sperm. This study attempted to achieve litters of a predetermined sex after a double insemination of sows with 160x10(6) sex-sorted, frozen-thawed sperm. Sows were synchronised and sperm were non-surgically inseminated into the proximal third of the uterine horn at 36 and 42 h after hCG administration. Sows inseminated with sex-sorted sperm achieved similar pregnancy rates to those receiving an equal dose of unsorted, frozen-thawed sperm. However, all sows conceiving after insemination with sex-sorted sperm returned to oestrus within 57 days of insemination. This was a higher rate of pregnancy loss than observed for sows inseminated with unsorted sperm (37.5%; P=0.031). A combination of low sperm numbers and potentially compromised developmental capability of embryos derived from sex-sorted sperm may have resulted in this early stage loss of pregnancy.

Field fertility of frozen-thawed boar sperm at low doses using non-surgical, deep uterine insemination

The lowest dose of frozen-thawed boar sperm used for deep uterine artificial insemination (DUI) of sows has been 100x10(6). A three stage field study was performed to establish to what level the dose of frozen-thawed sperm used for DUI could be reduced without adversely affecting the fertility of the sow. In stage 1, 15 sows were inseminated twice with 1000x10(6) fresh or frozen-thawed sperm at 24 and 36 h post-detection of oestrus. In stage 2, 262 sows were inseminated with 62.5, 250 or 1000x10(6) fresh or frozen-thawed sperm at 24, 36, or 24 and 36 h after detection of oestrus. Stage 3 involved post mortem investigation of the uterine lining to assess damage caused by insertion of the insemination catheter. All sows inseminated in stage 1 of the study farrowed. In stage 2, the non-return (NRR) and farrowing rates of each group were compared to a control double cervical insemination of 3250x10(6) fresh sperm. As few as 62.5x10(6) fresh sperm could be deposited at a single insemination without reduction in NRR or farrowing rates compared with the control group. A double DUI with 250x10(6) frozen-thawed sperm was required before fertility was equivalent to the controls. Investigation of the uterine lining after insertion of the DUI catheter revealed evidence of bleeding, warranting further investigation of the viability of widespread use of the Firflex catheter, despite the promising fertility achieved here with low doses of spermatozoa.

Non-surgical deep intra-uterine transfer of in vitro produced porcine embryos derived from sex-sorted frozen–thawed boar sperm

Embryos and offspring of a pre-determined sex have been produced in pigs using AI and IVF with unfrozen sperm, and after surgical insemination with sex-sorted frozen-thawed sperm. The aims of this study were to demonstrate that sex-sorted frozen-thawed boar sperm could be incorporated into pig IVF for the production of embryos of a pre-determined sex and that these embryos could be successfully non-surgically transferred. Oocytes were matured in vitro, fertilised with either unsorted or sex-sorted frozen-thawed sperm and cultured until the eight-cell stage. These embryos were then transferred to recipients (n = 7) non-surgically (n = 70 embryos per sow). Oocyte cleavage was similar between sex-sorted (1538/5044; 30.5%) and unsorted (216/756; 28.6%) frozen-thawed sperm, and PCR sex-determination of the embryos confirmed that they were of the predicted sex (n = 16). Delayed return to oestrus (>23 days) was observed in five recipient sows (71.4%). Fetal sacs were observed by transcutaneous ultrasound on Day 18 in one of these sows. Pre-sexed porcine IVP embryos can be successfully produced using sex-sorted frozen-thawed boar sperm, and these embryos are capable of initiating pregnancies when transferred to recipients. However, further refinement of porcine ET protocols are required to enable development to term.

Effects of platelet-activating factor and platelet-activating factor: acetylhydrolase on in vitro post-thaw boar sperm parameters

Cryopreservation of boar sperm compromises fertility after thawing by reducing sperm longevity and inducing acrosome reaction-like changes. In an attempt to improve the post-thaw motility and acrosome integrity of boar sperm, semen was frozen using a modified Westendorf method in which the medium was supplemented with either platelet-activating factor (PAF) or a recombinant platelet-activating factor:acetylhydrolase (PAF:AH; Pafase) before or after freezing. Platelet-activating factor is a phospholipid that is present in boar semen and PAF:AH is the naturally occurring enzyme that converts PAF to biologically inactive Lyso-PAF. Addition of PAF to the cryopreservation medium improved post-thaw motility immediately after thawing and after 3h incubation at 37 degrees C (60.0+/-0.0% and 25.0+/-2.9%; mean+/-S.E.M.) compared to the control sperm (41.7+/-1.7% and 10.0+/-2.9%; P<0.05). Acrosome integrity was higher immediately after thawing and after 3 and 6h incubation at 37 degrees C when sperm were frozen in the presence of Pafase (55.7+/-3.2%, 45.7+/-3.7% and 23.0+/-3.1%), compared to the control sperm (42.7+/-1.5%, 25.7+/-5.7% and 12.3+/-2.7%) and sperm frozen in the presence of PAF (33.0+/-3.7%, 26.3+/-2.2% and 11.7+/-0.3%; P<0.05). Addition of PAF to sperm after thawing improved motility immediately post-thaw (41.6+/-2.6%), compared with addition of Pafase (23.3+/-2.2%) or the control sperm with no supplementation of the medium (26.7+/-2.2%; P<0.05). However, this beneficial effect was lost by 3h post-thaw. Supplementation of boar semen cryopreservation medium with PAF and Pafase appeared to have beneficial effects on the in vitro quality of the sperm post-thaw.

Studies on the effect of supplementing boar semen cryopreservation media with different avian egg yolk types on in vitro post-thaw sperm quality

Fertility after insemination of cryopreserved boar semen is currently below that of fresh semen. In an attempt to improve the post-thaw motility and acrosome integrity of boar sperm, semen was frozen using an adapted Westendorf method in which the chicken egg yolk was replaced by either duck or quail egg yolk. The different composition of the yolk types, particularly the amount of cholesterol, fatty acids and phospholipids, were thought to potentially afford a greater level of protection to sperm against damage during freezing and thawing. Sperm frozen in medium containing chicken egg yolk displayed higher motility immediately after thawing, but there was no difference in the motility of sperm frozen with different types of egg yolk 3 or 6 h after thawing and maintenance at 37 degrees C. Sperm frozen in media containing chicken or duck egg yolk had a higher proportion of intact acrosomes immediately after thawing than sperm frozen in medium containing quail egg yolk, but 6 h after thawing and maintenance at 37 degrees C the sperm that had been frozen in medium containing chicken egg yolk had a higher proportion of intact acrosomes than the sperm frozen in media containing duck or quail egg yolk. Analysis of the composition of the different yolk types showed that the basic components of the yolks were similar, but the ratios of fatty acids and phospholipid classes differed. Duck egg yolk had more monounsaturated fatty acids (MUFA) than chicken egg yolk, which had more MUFA than quail egg yolk. Duck egg yolk contained more phosphotidylinositol (PI) than chicken or quail egg yolks and quail egg yolk contained more phosphotidylserine than either chicken or duck egg yolks. The differences in post-thaw motility and acrosome integrity of boar sperm when frozen in media containing the different types of egg yolk may be due to the variation in composition.

Relaxin Research in the Postgenomic Era

Because of the coevolution of ligands and their cognate receptors, analysis of human genomic sequences allows prediction of the pairing of these elements. Initially, we identified a group of five human leucine-rich repeat-containing G-protein-coupled receptor (LGR) genes homologous to LH, FSH, and TSH receptors. Based on common phenotypes of INSL3 null mice and transgenic mice with LGR8 gene deletion, we hypothesized that INSL3, relaxin, and related genes are likely ligands for the paralogous LGR7 and LGR8 genes. Matching the relaxin family peptides with these two orphan LGRs led to the finding that relaxin is capable of activating LGR7 and LGR8 through the Gs pathway. In addition, INSL3 and relaxin 3 were found to be specific ligands for LGR8 and LGR7, respectively. Based on the known production of INLS3 by testicular Leydig cells and ovarian theca cells, we demonstrated the expression of the INSL3 receptor LGR8 in oocytes in ovary and in male germ cells in the testis. Furthermore, we found that LH stimulates INSL3 transcripts in ovarian theca and testicular Leydig cells. INSL3, in turn, binds LGR8 expressed in germ cells to initiate the meiotic progression of arrested oocytes in preovulatory follicles in vitro and in vivo and to suppress male germ cell apoptosis in vivo. INSL3 interacts with germ cells to activate the inhibitory G protein, thus leading to decreases in cAMP production. Our data demonstrate the importance of the INSL3-LGR8 paracrine system in mediating gonadotropic actions in both ovary and testis.

304 PRODUCTION OF PORCINE EMBRYOS OF A PREDETERMINED SEX AFTER IN VITRO FERTILIZATION OF IN VITRO-MATURED OOCYTES WITH SEX-SORTED FROZEN-THAWED BOAR SPERM

Pre-sexed embryos and offspring have been produced after IVF and embryo transfer (ET) with sex-sorted frozen-thawed sperm in cattle and sheep (Maxwell et al. 2004 Anim. Reprod. Sci. 82–83, 79–95). The aims of this study were to demonstrate that sex-sorted frozen-thawed boar sperm could be incorporated into pig IVF for the production of embryos of a predetermined sex and that these embryos could be successfully nonsurgically transferred. Ovaries were collected from abattoir slaughtered gilts (n = 138) and selected COCs were matured in vitro (Long et al. 1999 Theriogenology 51, 1375–1390). Sperm were collected from a mature boar and diluted with Androhep (1:3, semen:Androhep; Minitube, Verona, WI, USA), stained with H33342, and separated into X and Y sperm using a SX MoFlo (Cytomation, Inc., Fort Collins, CO, USA). Sex-sorted sperm were cryopreserved in 0.5 mL straws using the Westendorf protocol modified for sorted sperm (Bathgate, unpublished). Thawed sperm (Y sperm only) were prepared for IVF by centrifugation (300g, 10 min) through a Porcipure gradient (Nidacon Int. AB, Gothenburg, Sweden), and washed (centrifugation 300g, 10 min) in mTALP-PVA. For IVF, COCs were denuded and groups of 100 oocytes were transferred to 200-μL drops of mTALP-PVA (Long et al. 1999) and incubated with 5,000 motile sperm for 4–6 (Short) or 18–20 h (Long) . Presumptive zygotes were washed and transferred to 100-μL drops of mNCSU-23 (Long et al. 1999) and cultured until Day 4 (Day 0 = IVF) in humidified 5% CO2, 6% O2, 89% N2. Oocyte cleavage was assessed 48 h post-insemination, and on Day 4 selected morulae were transferred to recipient sows (n = 7 Large White × Landrace; 65 morulae per sow) nonsurgically using a Firflex catheter (Magapor, Zaragoza, Spain). Sex of remaining embryos was confirmed by PCR and restriction analysis (Cong et al. 1993 Hum. Mol. Genet. 2 1187–1191). Data from three replicates were arc sin transformed and analyzed by ANOVA. Oocyte cleavage was similar after Short (724/1547; 46.8%) or Long (598/1528; 39.1%) co-incubation. Resort analysis showed sperm to be >91% purity, and all sexed morulae were of the predicted sex (16/16). Delayed return to estrus (>23 days) was observed in 5 recipient sows (71.4%). Fetal sacs were observed by transcutaneous ultrasound in one of these sows. Pre-sexed porcine IVP embryos can be successfully produced using sex-sorted frozen-thawed boar sperm, and these embryos are capable of initiating pregnancies when transferred to recipients. However, further refinement of porcine IVP and ET protocols are required to enable full in vivo development. This work was supported by XY, Inc., Fort Collins, CO, USA.

79 EFFECT OF PRE-FREEZE ADDITION OF PLATELET-ACTIVATING FACTOR AND PLATELET-ACTIVATING FACTOR:ACETYLHYDROLASE ON THE POST-THAW INTEGRITY OF FROZEN - THAWED BOAR SPERM

The use of frozen-thawed boar sperm is not widespread, owing to reduced fertility rates and high cost per dose (Eriksson et al. 2004 Proc. Aust. Assoc. Pig Vet., 61–69). Improvements in post-thaw sperm survival are required for commercialization. Platelet-activating factor (PAF) is a phospholipid involved in regulating sperm function. PAF:acetylhydrolase (PAF:AH) regulates PAF activity by conversion to its inactive isoform. Both occur naturally in boar semen (Kordan et al. 2003 Pol. J. Vet. Sci. 6, 55–60). Removal of PAF and PAF:AH along with seminal plasma during the cryopreservation process may inhibit the ability of sperm to withstand the freeze-thawing process. The aim of this study was to assess the effect of PAF and PAF:AH, added to boar semen pre-freeze, on the post-thaw motility and acrosome integrity of sperm. The sperm rich fraction was collected from a mature Large White × Landrace boar, diluted with Androhep (1:2, semen:Androhep; Minitube, Verona, WI, USA), cooled to 17°C over 2 h, and then centrifuged (10 min, 800g). The sperm pellet was resuspended in cooling extender (11% (w/v) lactose solution with 20% (v/v) egg yolk; control), cooling extender plus 100 ng/mL PAF (PAF), or cooling extender plus 0.4% (v/v) PAF:AH (Pafase; ICOS Corporation, Seattle, Washington, USA), and cooled to 5°C over 2.5 h. Sperm were further diluted with cooling extender plus 9% (v/v) glycerol and 1.5% (v/v) Equex STM (freezing extender), loaded into 0.5-mL straws, and frozen. Straws were thawed (20 s, 42°C) and the motility and acrosome integrity (FITC-PNA; Mortimer etal. 1990 Hum. Reprod. 5, 99–103) assessed at 0, 3, and 6 h post-thaw after incubation at 37°C. Data from three replicates were analyzed by ANOVA and a Tukey test applied where significant differences were found. Post-thaw motility (0 and 3 h) was higher for PAF (60.0 ± 0.0% and 25.0 ± 2.9%) than for control (41.7 ± 1.7% and 10.0 ± 2.9%; P < 0.05), but was similar for Pafase (41.7 ± 1.7% and 16.7 ± 1.7%; P > 0.05). By 6 h post-thaw, motility was similar for PAF (1.7 ± 1.7%), Pafase (6.7 ± 6.8%), and control (1.7 ± 1.7%, all respectively; P > 0.05). Acrosome integrity was higher at 0, 3 and 6 h post-thaw for Pafase (55.7 ± 3.2%, 45.7 ± 3.7% and 23.0 ± 3.1%) than for control (42.7 ± 1.5%, 25.7 ± 5.7% and 12.3 ± 2.7%) and PAF (33.0 ± 3.7%, 26.3 ± 2.2% and 11.7 ± 0.3%, all respectively; P < 0.05), but was similar between control and PAF (P > 0.05). Supplementation of cooling extender with 100 ng/mL PAF increased initial post-thaw motility, but this benefit was lost after 6 h post-thaw. Pafase in the cooling extender improved the proportion of intact acrosomes, even after 6 h post-thaw. In vitro studies investigating the interaction between Pafase-treated frozen-thawed sperm and oviducal epithelial cells would be of interest to further establish the potential benefits of pre-freeze addition of Pafase on the fertilizing potential of frozen-thawed boar sperm.

INSL5 Is a High Affinity Specific Agonist for GPCR142 (GPR100)

Insulin-like peptide 5 (INSL5) is a peptide that belongs to the relaxin/insulin family, and its receptor has not been identified. In this report, we demonstrate that INSL5 is a specific agonist for GPCR142. Human INSL5 displaces the binding of (125)I-relaxin-3 to GPCR142 with a high affinity (K(i) = 1.5 nM). In a saturation binding assay, (125)I-INSL5 binds GPCR142 with a K(d) value of 2.5 nM. In functional guanosine (gamma-thio)-triphosphate binding and cAMP accumulation assays, INSL5 potently activates GPCR142 with EC(50) values of 1.3 and 1.2 nM, respectively. In addition, INSL5 stimulates Ca(2+) mobilization in HEK293 cells expressing GPCR142 and G alpha(16). Overall, INSL5 behaves as an agonist for GPCR142 similar to relaxin-3. However, unlike relaxin-3, which is also a potent agonist for GPCR135 and LGR7, INSL5 does not activate either GPCR135 or LGR7. INSL5 inhibits (125)I-relaxin-3 binding to GPCR135 with a low potency (K(i) = 500 nM). A functional assay shows that INSL5 (1 microm) is a weak antagonist for GPCR135. In addition, INSL5 (up to 1 microm) shows no affinity or activity at LGR7 or LGR8 either in a binding assay or a bio-functional assay. Previously, we have demonstrated that GPCR142 mRNA is expressed in peripheral tissues, particularly in the colon. Here we show that INSL5 mRNA is expressed in many peripheral tissues, similar to GPCR142. The high affinity interaction between INSL5 and GPCR142 coupled with their co-evolution and partially overlapping tissue expression patterns strongly suggest that INSL5 is an endogenous ligand for GPCR142.

Integration of sperm sexing technology into the ART toolbox

Sex-sorting of mammalian spermatozoa has applications for genetic improvement of farm animals, in humans for the control of sex-linked disease, and in wildlife as a captive management strategy and for the re-population of endangered species. Considerable research has been undertaken worldwide on the Beltsville sperm sexing technology, the only effective method for pre-selection of sex of offspring. The combination of this method with assisted reproductive technologies has resulted in the birth of offspring in a wide range of animals, including cattle, the only livestock species in which sperm sexing is used commercially. Major improvements in the efficiency of sorting, in particular the development of high speed sorting (15 million X and Y spermatozoa per hour) have led to the production of offspring using conventional and low dose AI and the successful cryopreservation of sorted spermatozoa in cattle, sheep, horses and elk. A major limitation remains the short viable lifespan of sorted spermatozoa in the female genital tract, in most species necessitating sperm deposition deep in the uterus, and close to the expected time of ovulation, for acceptable fertility after in vivo insemination. Special deep uterine insemination technology has been employed to produce offspring in pigs and horses using low sperm doses. Considerable attention has been paid to reduction of the damage and capacitation-like changes to spermatozoa that result from flow cytometric sorting and from freezing and thawing. However, high-purity sorting of liquid-stored or frozen-thawed spermatozoa for immediate use, or re-cryopreservation for later use, does not reduce its fertilizing capacity in vitro, allowing its combination with in vitro fertilization or juvenile in vitro embryo transfer to produce blastocysts, and offspring in sheep and cattle after embryo transfer. Further research into sorting and preservation methods that incorporate strategies to prevent destabilization of sperm membranes may improve the fertilizing lifespan of flow cytometrically sorted spermatozoa. With continued improvement in sorting instrumentation and biological handling, sorting efficiency should reach a point where commercially acceptable pregnancy rates may be achieved in a number of species after conventional or deep uterine insemination.

Relaxin down-regulates renal fibroblast function and promotes matrix remodelling in vitro

BACKGROUND

Renal fibroblasts are important effector cells in tubulointerstitial fibrosis, with experimental antifibrotic strategies focusing on the functional down-regulation of these cells. Several experimental models of fibrosis have provided evidence for the effectiveness of the polypeptide hormone relaxin as a potential antifibrotic agent. This study was conducted to further elucidate the antifibrotic mechanisms of relaxin on renal fibroblasts in vitro.

METHODS

Rat cortical fibroblasts were obtained from outgrowth culture of renal tissue isolated from kidneys 3 days post-unilateral ureteric obstruction and constituted 100% of cells studied. A relaxin radio-receptor assay was used to establish binding of relaxin to renal fibroblasts in vitro. Functional studies then examined the effects of H2 relaxin (0, 1, 10 and 100 ng/ml) on fibroblast kinetics, expression of alpha-smooth muscle actin (alpha-SMA), total collagen synthesis, collagenase production and collagen-I lattice contraction. CTGF mRNA expression was also measured by northern analysis.

RESULTS

H2 relaxin bound with high affinity to rat renal fibroblasts, but receptor numbers were low. Consistent with its previously reported bimodal effect, transforming growth factor (TGF-beta 1) reduced fibroblast proliferation, an effect abrogated by H2 relaxin. Fibroblasts exposed to H2 relaxin (100 ng/ml) for 24 h demonstrated decreased immunostaining for alpha-SMA and reduced alpha-SMA protein expression compared with controls. There was a trend for a relaxin-mediated reduction in total collagen synthesis and alpha 1(I) mRNA expression with large dose-related increases in collagenase protein expression being observed. TGF-beta 1-stimulated collagen-I lattice contraction was significantly inhibited following co-incubation with 100 ng/ml relaxin. Incremental doses of H2 relaxin had no significant effect on CTGF mRNA expression.

CONCLUSIONS

The findings of this study suggest that the antifibrotic effects of relaxin involve down-regulation of fibroblast activity, increase in collagenase synthesis and restructuring of collagen-I lattices, which are consistent with its known physiological role of matrix remodelling. Although there appears to be an interaction between TGF-beta 1 and H2 relaxin, this does not appear to involve a reduction in CTGF mRNA expression.

The structure and regulation of the oxytocin receptor

The oxytocin receptor (OTR) is part of an ancient hormone system expressed in diverse phyla in relation to acute reproductive smooth muscle responses, such as egg-laying, birth, or milk letdown. The regulation of the OTR gene, while correlating with steroid levels in vivo, remains elusive. There appear to be both inhibitory and stimulatory influences acting upon a constitutive pattern of basal expression. We have found no evidence, however, for an effect of the sex steroids either directly on gene transcription, or on the receptor itself at the protein level. In the prostatic carcinoma cell line Du145, we have shown that up-regulation of the OTR gene transcription can be effected by cAMP. In an attempt to characterize the expression of the OTR protein in vivo, we have shown, using ligand-blotting, that the OTR can be expressed at different sizes in transfected cells and in myometrium. Also, in the myometrium at term, immunohistochemistry suggests that there is both an increase in OTR protein per cell, as well as in the number of smooth muscle cells expressing OTR, emphasizing that perinatal changes are the results of both individual gene activation events and gross cellular differentiation. The OTR is a valuable model system reflecting molecular changes in the perinatal period. When we understand how this important molecule is regulated, we will also be a long way towards understanding the mechanisms controlling myometrial contractility at birth. Experimental Physiology (2001) 86.2, 289-296.

Characterization and functional significance of calcium transients in the 2-cell mouse embryo induced by an autocrine growth factor

Growth of preimplantation embryos is influenced by autocrine trophic factors that need to act by the 2-cell stage, but their mode of action is not yet described. This report shows that late zygote and 2-cell stage mouse embryos responded to embryo-derived platelet-activating factor (PAF) with transient increases in intracellular calcium concentration ([Ca(2+)](i)). [Ca(2+)](i) transients were single global events and were specifically induced by embryo-derived PAF. They were blocked by inhibition of phospholipase C (U 73122) and an inositol trisphosphate (IP(3)) receptor antagonist (xestospongin C), indicating the release of calcium from IP(3)-sensitive intracellular stores. Transients were also inhibited by the absence of calcium from extracellular medium and partially inhibited by treatment with dihydropyridine (nifedipine, 10 micrometer), but not pimozide (an inhibitor of an embryonic T-type calcium channel). (+/-)BAY K8644 (an L-type channel agonist) induced [Ca(2+)](i) transients, yet these were completely inhibited by nifedipine (10 micrometer). The complete inhibition of BAY K8644, but only partial inhibition of PAF by nifedipine shows that L-type channels were only partly responsible for the calcium influx. Depolarization of 2-cell embryos by 50 mm K(+) did not inhibit PAF-induced calcium transients, showing that the influx channels were not voltage-dependent. Depletion of intracellular calcium stores by thapsigargin revealed the presence of store-operated channels. The interdependent requirement for IP(3)-sensitive internal calcium stores and extracellular calcium in the generation of PAF-induced transients may be explained by a requirement for capacitative calcium entry via store-operated channels. A functionally important role for the PAF-induced transients is supported by the observation that inhibition of [Ca(2+)](i) transients by a PAF-antagonist (WEB 2086) or an intracellular calcium chelator (1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetrakis-acetoxymethyl ester; BAPTA-AM) caused marked inhibition of early embryo development. Growth inhibition by BAPTA-AM was relieved by addition of exogenous PAF.