Proteomic analyses were done on 2 chemosensory appendages of the lone star tick, Amblyomma americanum. Proteins in the fore tarsi, which contain the olfactory Haller's organ, and in the palps, that include gustatory sensilla, were compared with proteins in the third tarsi. Also, male and female ticks were compared. Proteins were identified by sequence similarity to known proteins, and by 3-dimensional homology modeling. Proteomic data were also compared with organ-specific transcriptomes from the tick Rhipicephalus microplus. The fore tarsi express a lipocalin not found in the third tarsi or palps. The fore tarsi and palps abundantly express 2 proteins, which are similar to insect odorant-binding proteins (OBPs). Compared with insect OBPs, the tick OBP-like sequences lacked the cysteine absent in C-minus OBPs, and 1 tick OBP-like sequence had additional cysteines that were similar to C-plus OBPs. Four proteins similar to the antibiotic protein microplusin were found: 2 exclusively expressed in the fore tarsi and 1 exclusively expressed in the palps. These proteins lack the microplusin copper-binding site, but they are modeled to have a significant internal cavity, potentially a ligand-binding site. Proteins similar to the dust mite allergens Der p7 and Der f 7 were found differentially expressed in female fore tarsi. A protein exclusively expressed in the fore tarsi has similarities to Neto, which is known to be involved in clustering of ionotropic glutamate receptors. These results constitute the first report of OBP-like protein sequences in ticks and point to several research avenues on tick chemosensory reception.

The European roe deer (Capreolus capreolus) was the first mammal in which embryonic diapause has been described. While diapause is characterized by a complete developmental arrest in some species, roe deer blastocysts show a very slow, yet continuous growth. To date, it is neither known whether this growth is accompanied by developmental progression nor whether it is uniform in both, the trophectoderm (TE) and the inner cell mass (ICM). We collected roe deer blastocysts during the regular hunting season from September 2018 to January 2019, and quantified the fraction of cells expressing the proliferation marker Ki67 by immunofluorescence and light-sheet microscopy. We found that the cell number increased from around 300 cells in September to over 20'000 cells per blastocyst in December before elongation occured. Concurrently, we observed considerable morphological changes, i.e. cavity formation and transition to a disk-like shape of the inner cell mass. During diapause, less than 10% of all cells displayed positive Ki67 staining. Strikingly, the relative increase in cell number was lower in the ICM compared to the TE, whereas the fraction of Ki67 positive cells appeared to be lower in the TE than in the ICM. Our findings thus confirm that roe deer blastocysts display developmental progression in the course of diapause. We hypothesize that while the overall duration of the cell cycle is longer in the ICM than in the TE, the fractional distribution of cell cycle phases differs, with TE cells having a longer G1 phase than cells of the ICM.

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Prepubertal bovine donors are currently used for commercial breeding to accelerate the genetic gain and decrease the generation interval. Nevertheless, it has been reported that their oocyte developmental competence is lower than in adult females. Addition of cAMP regulators during in vitro maturation (IVM) has been suggested to enhance blastocysts rates (Albuz et al. 2010 Hum. Reprod. 25, 2999–3011). Here, we evaluated the effects of the cAMP modulators forskolin, 3-Isobutyl-1-methylxanthine (IBMX), and cilostamide during extended IVM on the developmental capacity of oocytes from prepubertal and adult bovine females. A total of 1851 oocytes from 24 lactating cows (>2 lactations) and 24 prepubertal donors (6–10 mo old) were collected by transvaginal oocyte recovery (OPU) twice per week and divided into 3 experiment groups: (1) TCM24 (OPU medium: PBS; 24 h of IVM; standard protocol/control); (2) cAMP30 [OPU medium: PBS-IBMX (500 μM); 2 h pre-IVM culture using forskolin (100 μM)-IBMX (500 μM) and 30 h of IVM adding cilostamide (20 μM)], and (3) DMSO30 [cAMP modulators are diluted in DMSO)/vehicle control; OPU medium: PBS-DMSO (46.3 mM); 2 h pre-IVM culture (280 mM DMSO) and 30 h IVM (5.6 mM DMSO)]. Following IVM, oocytes were either submitted to in vitro fertilization and embryo culture or fixed in 1% glutaraldehyde at 9, 20, 24, and 30 h after IVM and stained with Hoechst to evaluate their nuclear status. One-way ANOVA was implemented to evaluate recovered oocytes and meiotic stages. The Glimmix procedure from SAS/STAT was performed to compare blastocyst and cleavage rates. Total number of oocytes and IVM-suitable oocytes per donor per OPU session were similar in adult and prepubertal donors (total number/IVM suitable; prepubertal donors: 6.7/4.2, 6.4/4.0, 6.5/3.8; cows: 6.2/4.7, 6.2/4.4, 6.2/4.5 for TCM24, cAMP30 and DMSO30, respectively). At 9 h, cAMP regulators were able to maintain meiotic arrest in prepubertal and adult donors (GV: 80.0 and 40.9%, respectively) compared to standard IVM (GV: 61.1 and 31.2%) and DMSO30 (GV: 40.0 and 26.6%) protocols (P < 0.05). Using the cAMP30 protocol, the percentage of oocytes that reached MII stage at 20 h was lower in adult (4.5%) and prepubertal donors (5.26%) compared to the DMSO30 (50.0 and 42.8%, respectively) and TCM24 (56.2 and 44.4% respectively) protocols. Metaphase II rates after either 24 or 30 h were similar among treatments (prepubertal donors: 88.2, 70.5, and 84.2%; cows: 71.4, 85.7, and 81.2% for TCM24, cAMP30, and DMSO30, respectively; P > 0.05). Cleavage rates (prepubertal donors: 63.4, 54.9, and 52.1%, cows: 56.1, 57.8, and 51.6% for TCM24, cAMP30, and DMSO30, respectively) and blastocysts/presumptive zygotes rates (prepubertal donors: 26.2, 19.6, and 16.2%; cows: 27.5, 28.1, and 21.5% for TCM24, cAMP30, and DMSO30, respectively) did not show significant differences (P > 0.05). Although cAMP modulators delayed the progression through meiosis in adult and prepubertal oocytes, similar blastocysts rates were obtained. Our results suggest so far that oocyte retrieval and competence in prepubertal donors can be similar to that of the adult donors with and without addition of cAMP modulators.

Prepubertal bovine females have been suggested as a source of oocytes in order to accelerate genetic gain and decrease the generation interval. However, prepubertal oocytes have a lower developmental competence than their adult counterparts. In vitro maturation (IVM) systems using cyclic AMP (cAMP) regulators and 30-h culture have been suggested to improve blastocyst in vitro production rates from bovine oocytes (Albuz et al., 2010). The present study evaluated the effects of an addition of the cAMP modulators forskolin, 3-isobutyl-1-methylxanthine (IBMX), and cilostamide during extended IVM on blastocyst yields and gene expression in prepubertal and adult bovine females. Holstein-Friesian donors were submitted to ovum pick-up twice per week. Oocytes from groups of 12 animals, including lactating cows (>2 lactations) and prepubertal donors (6–10 months old) were used in the following treatment groups: TCM24 (24-h IVM, routine protocol/control), cAMP30 (2-h pre-IVM culture using forskolin-IBMX and 30-h IVM adding cilostamide), DMSO30 [2-h pre-IVM culture and 30-h IVM with dimethyl sulfoxide (DMSO)/vehicle control]. In vitro-matured oocytes were fertilized and presumptive zygotes were cultured in vitro to assess embryo development. In vivo blastocysts were produced from superovulated cows and used for gene expression analysis. Cleavage rates, blastocyst formation, and mRNA abundance of selected genes were evaluated. The Glimmix procedure from SAS/STAT (SAS Institute Inc., Cary, NC, USA) was performed to compare blastocyst and cleavage rates. One-way ANOVA was implemented to evaluate gene expression. A total of 793 oocytes from the different sources were submitted to the IVM treatments. Cleavage rates (prepubertal donors: 64.6 ± 4%, 59.1 ± 6.4%, 53 ± 4.4%, cows: 55.1 ± 4.3%, 59 ± 6.5%, 50.8 ± 4.4%, for TCM24, cAMP30, and DMSO30, respectively; P > 0.05) and blastocyst/zygotes rates (prepubertal donors: 27 ± 6%; 21.8 ± 3.5%; 17.6 ± 2.4%; cows: 28 ± 3.3%; 27.7 ± 2.9%; 22.7 ± 3.2% for TCM24, cAMP30, and DMSO30, respectively; P > 0.05) did not differ among in vitro treatments. The mRNA relative abundance of the EGR1 gene was down-regulated 6-fold in all in vitro-produced blastocysts compared with their in vivo counterparts (P < 0.05). Gene expression profiles for SLC2A8, DNMT3B, BCL-XL, and PRDX1 were similar in in vitro and in vivo blastocysts. These results show similar embryo production patterns in prepubertal and adult donors. Furthermore, DMSO did not show effects on embryo developmental rates when used during IVM. The gene expression levels of EGR1 confirm our recent findings in blastocysts obtained from oocytes from slaughterhouse ovaries (data not presented), showing its usefulness as an embryo quality marker. These preliminary results indicate that oocyte developmental capacity in prepubertal donors can be similar to that of the adult donors without addition of cAMP modulators.

Bovine oocytes and embryos have been established as a valuable model for studying human early development, specifically after assisted reproductive technologies (ART). Efforts for the improvement of ART in the last years have focused on culture media and conditions. Recently, Albuz et al. (2010) reported that the culture of bovine cumulus–oocyte complexes (COC) with cyclic adenosine 3′, 5′-monophosphate (cAMP) modulators, before and during extended in vitro maturation (IVM), improved blastocyst quality and yields in mice and cattle. In this study, we investigated the influence of an extended IVM phase in combination with cAMP modulators on blastocyst yields and quality, the effects on mRNA expression profiles and epigenetic marks. We compared these results to the standard protocol (Wrenzycki et al., 2001) used in our laboratory with oocytes from different retrieval methods. Oocytes were retrieved from slaughterhouse ovaries either by slicing or follicular aspiration. The COC were either subjected directly to IVM using the standard TCM-based protocol for 24 h (TCM24-slicing and TCM24-aspiration, respectively) or oocytes that were retrieved by aspiration were treated with forskolin and IBMX for a 2-h pre-IVM period, followed by an extended IVM phase of 30 h in TCM, supplemented with cilostamide (cAMP30-aspiration). Statistical analyses were performed using 1-way ANOVA followed by the nonparametrical Kruskal–Wallis test. Maturation rates were 79.3 ± 2.6% in TCM24-aspiration, 74.2 ± 8.8% in cAMP30-aspiration and 70.4 ± 5.1% in TCM24-slicing oocytes. Matured oocytes were fertilized in vitro with semen from a bull previously proven to be suitable for IVF. Blastocyst rates from presumptive zygotes were significantly higher (P = 0.003) in the TCM24-aspiration group (32 ± 7%) compared to TCM24-slicing (23 ± 7%) and cAMP30-aspiration (22 ± 5%). Analysis revealed that cell numbers were rather similar in the 3 experimental groups (125 ± 19, 128 ± 15 and 129 ± 9), while in vivo-produced blastocysts possessed slightly more cells (134 ± 17; P ≥ 0.05). RT-qPCR analysis of mRNA expression for a panel of genes indicative of embryo quality including DNMT3a, SLC2A8, COX2 and PCK2, showed that blastocysts derived from both aspiration protocols were similar to in vivo embryos, but were different from blastocysts resulting from the ovary-slicing protocol. Specifically, the expression profile of COX2, which is involved in pregnancy outcome and in the response to growth factors, indicates an enhanced developmental competence of aspirated oocytes. However, the transcript level of EGR1 (early growth response) was significantly higher (P = 0.009) in in vivo-derived blastocysts in comparison to all in vitro treatments. The investigation of the epigenetic status of the in vitro-derived blastocysts based on bisulfite sequencing of 2 satellite repeat sequences is currently underway. Results so far indicate that the method of obtaining the oocytes (slicing vs aspiration) for in vitro production of bovine embryos is of greater influence on blastocyst quality than IVM conditions.

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