Effects of once- versus twice-weekly transvaginal follicular aspiration on bovine oocyte recovery and embryo development

Ultrasound-guided transvaginal follicular aspiration combined with in vitro maturation/in vitro fertilization (IVM/IVF) and culture was used to obtain bovine preimplantation stage embryos. Evaluated were the effects of aspiration frequency on oocyte recovery and embryo development following IVM/IVF. In Experiment 1, transvaginal follicular aspiration was performed once (n=5) or twice (n=5) weekly in multiparous Angus cows with the aid of a transvaginal sector transducer (5-MHz). In Experiment 2, aspiration was performed on Angus cows once weekly (n=6), twice weekly (n=4), or twice weekly after treatment with FSH (15 mg; n=4). Follicles (>2 mm) were punctured using a 55-cm needle (17g), and oocytes were aspirated through the needle and silastic tubing (2 m) by vacuum suction (75 mmHg). The oocytes were examined for morphology and were in vitro matured and fertilized. Following IVF, all ova were co-cultured in vitro for 7 d on Buffalo Rat liver cells. Oocyte recovery rates per asp?ration session in Experiment 1 were not different between groups aspirated once or twice weekly (6.8+/-2.0 vs 6.3+/-1.1 oocytes/session; x+/-SEM) or in Experiment 2 between groups aspirated once, twice, or twice plus FSH treatment (7.7+/-1.8 vs 9.5+/-1.1 vs 6.2+/-1.1; P>0.10). In vitro development to the blastocyst stage was not different between the once, twice or twice-weekly aspiration plus FSH treatments or control oocytes obtained from cows at slaughter (23.1 vs 26.1 vs 18.0 vs 27.9%; P>0.10). Oocytes from the twice-weekly and twice-weekly plus FSH aspiration groups generated a higher percentage of Grade-1 quality embryos than the once-weekly group (P<0.05). In commercial bovine oocyte aspiration, more transferable embryos can be generated from twice-weekly aspirations than from once-weekly aspiration.     

Substructural specificity and polyvalent carbohydrate recognition by the Entamoeba histolytica and rat hepatic N- acetylgalactosamine/galactose lectins

Both the Entamoeba histolytica lectin, a virulence factor for the causative agent of amebiasis, and the mammalian hepatic lectin bind to N-acetylgalactosamine (GalNAc) and galactose (Gal) nonreducing termini on oligosaccharides, with preference for GalNAc. Polyvalent GalNAc- derivatized neoglycoproteins have >1000-fold enhanced binding affinity for both lectins (Adler,P., Wood,S.J., Lee,Y.C., Lee,R.T., Petri,W.A.,Jr. and Schnaar,R.L.,1995, J. Biol. Chem ., 270, 5164-5171). Substructural specificity studies revealed that the 3-OH and 4-OH groups of GalNAc were required for binding to both lectins, whereas only the E.histolytica lectin required the 6-OH group. Whereas GalNAc binds with 4-fold lower affinity to the E.histolytica lectin than to the mammalian hepatic lectin, galactosamine and N-benzoyl galactosamine bind with higher affinity to the E. histolytica lectin. Therefore, a synthetic scheme for converting polyamine carriers to poly-N-acyl galactosamine derivatives (linked through the galactosamine primary amino group) was developed to test whether such ligands would bind the E.histolytica lectin with high specificity and high affinity. Contrary to expectations, polyvalent derivatives including GalN6lys5, GalN4desmosine, GalN4StarburstTMdendrimer, and GalN8StarburstTMdendrimer demonstrated highly enhanced binding to the mammalian hepatic lectin but little or no enhancement of binding to the E.histolytica lectin. We propose that the mammalian hepatic lectin binds with greatest affinity to GalNAc "miniclusters," which mimic branched termini of N-linked oligosaccharides, whereas the E.histolytica lectin binds most effectively to "maxiclusters," which may mimic more widely spaced GalNAc residues on intestinal mucins.      

Enhanced glycolysis after maturation of bovine oocytes in vitro is associated with increased developmental competence

The effect of maturation in vitro on metabolism of individual bovine oocytes was examined. Three maturation media were used: standard, consisting of tissue culture medium 199 supplemented with serum and pyruvate, and a chemically defined medium supplemented with either amino acids or lactate. Development to blastocyst was significantly higher (P < 0.05) after maturation in standard medium (47%) than in defined medium with lactate (17%) but was not different than maturation in defined medium with amino acids (29%). Glucose metabolism through the Krebs cycle was not different after maturation in standard or defined medium with amino acids or lactate (0.48, 0.43, 0.38 pmol/oocyte/3 hr, respectively) but was affected by the removal of unlabeled pyruvate from the metabolic measurement medium (0.16, 0.21, 0.27 pmol/oocyte/3 hr, respectively). When physiological concentrations of glucose (0.52 mM) and pyruvate (0.5 mM) were used, oxidation of pyruvate was not different after maturation in standard or defined medium with amino acids or lactate (1.38, 1.13, 1.13 pmol/ oocyte/3 hr, respectively); however, glycolysis was significantly increased (P < 0.05) in treatments that supported higher blastocyst development (standard medium, 1.77 pmol/oocyte/3 hr; defined medium with amino acids, 1.58 pmol/oocyte/3 hr; defined medium with lactate, 1.32 pmol/oocyte/3 hr). Metabolism of glucose through the Krebs cycle was low in all media. In contrast, oxidation of pyruvate readily occurred after maturation in vitro. Metabolism of glucose through the Embden-Meyerhof pathway is important during oocyte maturation in vitro, and higher glycolytic rates in in vitro matured oocytes may reflect increased developmental competence.     

Influence of time of gene microinjection on development and DNA detection frequency in bovine embryos

The effect of DNA microinjection at various times afterin vitro insemination on DNA detection and survival rates of bovine embryos was investigated. Oocytes were inseminated 24 h after maturation with frozen/thawed semen prepared with a Percoll separation procedure. At 11, 15 and 19 h after insemination, embryos were centrifuged to visualize pronuclei and microinjected with a murine whey acidic protein-human protein C genomic DNA construct. After culture for 7 days on Buffalo Rat Liver cells, embryos were assessed for stage of development and assayed for the presence of the transgene by polymerase chain reaction. Of zygotes in the 11h after insemination treatment, 16% (25/152) of non-injected and 7% (11/161) of injected embryos developed to the morula or blastocyst stage. Comparable development of non-injected and injected embryos treated at 15h after insemination was 15% (23/158) and 4% (6/159) and treated at 19 h after insemination was 14% (23/162) and 1% (1/165), respectively. Development of injected embryos was greater (p<0.05) when injection was performed at 11 h after insemination compared to 19 h after insemination. Development of non-injected embryos was greater (p<0.01) than that of injected embryos. There was no difference in transgene detection frequency in embryos of all developmental states between treatments (53% at 11; 50% at 15; 48% at 19h after insemination). Injected embryos testing positive for the presence of the transgene exhibited increased development over negative embryos (p<0.01). Greater development efficiencies can be obtained in microinjected bovine embryos when injection is performed early in pronuclear formation.     

Development of goat embryos after in vitro fertilization and parthenogenetic activation by different methods.

Effective activation protocols that can be used during nuclear transfer investigations in goats need to be developed. We compared the development of IVF goat embryos with those of nonfertilized parthogenetically developing oocytes activated by treatment with either ionomycin or ethanol, both followed by immediate exposure to 6-diethylaminopurine (6-DMAP). Cumulus oocyte complexes (COCs) recovered from abattoir goat ovaries were either matured in a conventional laboratory incubator or placed in pre-equilibrated maturation medium and shipped overnight in a battery-operated dry incubator to another laboratory. Mature COCs were allocated randomly to one of three treatment groups. Group 1 oocytes (n=169 shipped, n=253 not shipped) were fertilized in vitro at 24 h postmaturation (hpm). The remaining COCs were activated at 28 hpm in either ionomycin (Group 2: n=362 shipped, n=202 not shipped), or ethanol (Group 3: n=263 shipped, n=249 not shipped). Activated oocytes were immediately incubated in 6-DMAP for 4 h. Blastocyst development was evaluated on Day 8 post-insemination/activation. Percent cleavage was comparable in shipped and nonshipped oocytes and in all treatment groups. In both shipped and nonshipped oocytes, parthenotes developing from ionomycin- and ethanol-activated oocytes had significantly greater blastocyst development (P<0.01) compared to IVF embryos (28.5 +/- 3.0, 27.4 +/- 2.8, 10.3 +/- 3.0, respectively for the nonshipped oocytes and 9.9 +/- 2.1, 10.3 +/- 2.4, 3.7 +/- 4.7 respectively for the shipped oocytes). Shipped oocytes had lower blastocyst development compared to nonshipped oocytes in the three treatment groups. The mean blastocyst cell number was not statistically different between shipped and nonshipped oocytes or among treatment groups, suggesting that all were equally viable.     

Metabolism, protein content, and in vitro embryonic development of goat cumulus-oocyte complexes matured with physiological concentrations of glucose and L-lactate

No information is available concerning how the maturation environment controls the metabolism of goat oocytes. The objectives of this experiment were to: (1) Determine the concentrations of glucose, lactate, and pyruvate in caprine follicular fluid; and (2) Investigate the effects of physiological concentrations of glucose and lactate in the in vitro maturation (IVM) medium on the metabolism (glycolysis and pyruvate oxidation), protein content, and developmental competence of caprine oocytes and cumulus-oocyte complexes (COCs). Abattoir-derived COCs were matured for 18-20 hr in a defined, SOF-based medium containing 0.75, 1.5 (follicular fluid = 1.4 mM), or 3.0 mM glucose, and 3.0, 6.0 (follicular fluid = 7.1 mM), or 12.0 mM L-lactate. The protein content of oocytes and COCs was not affected (P > 0.05) by the concentration of glucose and lactate in the maturation medium. Increasing glucose and lactate decreased (P < or = 0.05) glycolytic activity of oocytes, without affecting (P > 0.05) pyruvate oxidation. In COCs, increasing glucose concentrations tended (P = 0.07) to decrease glycolysis. When metabolic activity was corrected for protein content (pmol/microg protein/3 hr), increasing glucose or lactate concentrations in the medium decreased (P < or = 0.05) pyruvate oxidation in oocytes, but increased (P < or = 0.05) pyruvate oxidation in COCs. Embryonic development (cleavage and blastocyst development, hatching, and cell number) was not affected (P > 0.05) by the glucose and lactate concentrations tested. These results indicate that concentrations of glucose and lactate in the medium have cell type-specific effects on metabolism of oocytes and COCs, but do not affect developmental competence within the range of concentrations tested.     

Microbiological quality of tomato (<i>Solanum lycopersicum</i> L.) produced under greenhouse conditions in five Municipalities of the State of Mexico

The aim of the current research was to determine tomato (Solanum lycopersicum L.) microbiological quality produced under greenhouse conditions in 5 municipalities of the State of Mexico. Studies were conducted during the 2013 production cycle to know the risks and apply prevention strategies prior to its consumption. A microbiological analysis of samples of irrigation water, soil and 100 tomato fruits variety cid was performed to determine Aerobic Mesophiles, Total Coliforms and Fecal Coliforms. The methodology used were those according to the Official Mexican Standards NOM- 109-SSA1-1994, NOM-110-SSA1-1994, NOM-092-SSA1-1994, NOM-113-SSA1-1994, and the Regulations of the National French Organization for Standardization (AFNOR) NF V08-60, and NOM-093-SSA1-1994, which establish the allowable limits for the study microorganisms. The results showed a zero level of pollution in water and soil samples. For fruits, levels of Aerobic Mesophilic were within the maximum limits permitted by the standards. The municipality of Texcaltitlan showed the highest average for these microorganisms (10083.80 CFU/mL). Huixquilucan showed 2266.84 CFU/mL for Total Coliforms. For Fecal Coliforms, municipalities of Coatepec and Texcaltitlan exceeded the allowed limit.