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E Mullaart

Publications and source records attributed to E Mullaart.

At least 19 recordsLinked to original sources
PubMed2006

Effects of insemination-ovulation interval on fertilization rates and embryo characteristics in dairy cattle.

The objective of this study was to examine effects of the interval between insemination and ovulation on fertilization and embryo characteristics (quality scored as good, fair, poor and degenerate; morphology; number of cell cycles and accessory sperm number) in dairy cattle. Time of ovulation was assessed by ultrasonography (every 4h). Cows were artificially inseminated once between 36h before ovulation and 12h after ovulation. In total 122 oocytes/embryos were recovered 7d after ovulation. Insemination-ovulation interval (12h-intervals) affected fertilization and the percentages of good embryos. Fertilization rates were higher when AI was performed between 36-24 and 24-12h before ovulation (85% and 82%) compared to AI after ovulation (56%). AI between 24 and 12h before ovulation resulted in higher percentages of good embryos (68%) compared to AI after ovulation (6%). Insemination-ovulation interval had no effect on number of accessory sperm cells and number of cell cycles when corrected for embryo quality. This study showed that the insemination-ovulation interval with a high probability of fertilization is quite long (from 36 to 12h before ovulation). However, the insemination-ovulation interval in which this fertilized oocyte has a high probability of developing into a good embryo is shorter (24-12h before ovulation).

Animals↗
PubMed2003

Follicular dynamics around the recruitment of the first follicular wave in the cow.

The present study aimed to test the generally accepted view that a follicular wave starts with follicles newly recruited from the population smaller than 3 mm, which later compete for dominance. According to this view, subordinate follicles are expected to be too atretic to join the next follicular wave. Ten cows were ovariectomized shortly prior to the LH surge, thus around the start of the first follicular wave of the cycle. Per cow, on average, 14.4 follicles of >/=3 mm were dissected. Follicular health was determined on the basis of four parameters: 1) judgment of the degree of atresia by stereomicroscope, 2) incidence of apoptotic nuclei among the granulosa cells, 3) estradiol and progesterone concentrations, and 4) insulin-like growth factor-I (IGF-I) binding proteins (IGFBPs)-2, -4, and -5 concentrations in the follicular fluid. In addition to the preovulatory follicle, 3.1 other follicles, mainly sized 3-4.5 mm, were found to be healthy based on the proportion of apoptotic nuclei, and concentrations of estradiol/progesterone, and IGFBPs. The ability of these follicles to respond with growth on the preovulatory and periovulatory FSH surges was supported by a comparison to the follicular population of four cows 31-68 h after the LH surge. The present results point to an alteration of the view on the follicular wave. The larger follicles during the first days of the follicular wave are, in general, derived from follicles that also joined the previous wave. A portion of these growing follicles are estradiol active and compete for dominance. Other growing follicles lack estradiol production and are probably derived from rather atretic follicles. The first newly recruited follicles do not reach the size of 3 mm before 31 h after the preovulatory FSH surge. At that time, the larger follicles are already competing for dominance.

Animals↗
PubMed2003

Factors affecting oocyte quality and quantity in commercial application of embryo technologies in the cattle breeding industry.

With the introduction of multiple ovulation, embryo recovery and transfer techniques (MOET) plus embryo freeze-thaw methods in the early 1980s, the breeding industry has the tools in hand to increase the number of calves from donors of high genetic merit. In the early 1990s, the introduction of ovum pick-up followed by in vitro embryo production (OPU-IVP) opened up even greater possibilities. Using these technologies, we challenge biological mechanisms in reproduction. Where normally one oocyte per estrous cycle will develop to ovulation, now numerous other oocytes that otherwise would have degenerated are expected to develop into an embryo. Completion of oocyte growth and pre-maturation in vivo before final maturation both appear to be essential phases in order to obtain competence to develop into an embryo and finally a healthy offspring. In order to increase oocyte quality and quantity in embryo production technologies, current procedures focus primarily on improving the homogeneity of the population of oocytes with regard to growth and state of pre-maturation at the start of a treatment. In the case of MOET, dominant follicle removal (DFR) before superovulation treatment improves the number of viable embryos per session from 3.9 to 5.4 in cows but not in heifers and a prolonged period of follicle development obtained by preventing release of the endogenous LH surge increases the number of ova but not the number of viable embryos per session. In the case of OPU-IVP, the frequency of OPU clearly affects quantity and quality of the collected oocytes and FSH stimulation prior to OPU every 2 weeks resulted in 3.3 embryos per session. Analysis of 7,800 OPU sessions demonstrated that the oocyte yield is dependent on the team, in particular, the technician manipulating the ovaries. It is concluded that an increased understanding of the processes of oocyte growth, pre- and final maturation will help to improve the efficiency of embryo technologies. However, somewhere we will meet the limits dictated by nature.

Animals↗
PubMed2000

Effects of different reproduction techniques: AI MOET or IVP, on health and welfare of bovine offspring.

Since the introduction of in vitro production (IVP) of bovine and sheep pre-implantation embryos, increased birth weights and other deviations of IVP calves and lambs compared with AI or MOET offspring have been reported. Study 1 of the present paper, a comparison between AI, MOET and IVP (co-culture/serum) calves with respect to calf and calving characteristics in large-scale field conditions, confirms these reports. In addition, it is shown that MOET calves tend towards higher birth weights and have significantly longer gestations and more difficult calvings than AI calves. It is presently unknown if the effect of IVP is also observed later in life. In this paper, data on reproduction characteristics of bovine IVP co-culture/serum offspring are presented. Semen production--and non return data of one year old IVP bulls and superovulation-, AI- and OPU/IVP results of one year old IVP heifers are compared with those of one year old AI and MOET animals producing semen or embryos in the same time period. So far, there are no indications that the use of IVP is reflected in deviate reproduction characteristics of bovine IVP offspring. It has been suggested that use of co-culture cells and serum during in vitro culture of bovine (and sheep) embryos may partially explain the increased birth weights and other deviations of bovine and sheep IVP offspring. Deletion of these factors in semi-defined culture media, e.g. Synthetic Oviductal Fluid (SOF), could result in more normal offspring. Study 2 investigates this hypothesis in both field conditions (Study 2a, comparing AI, IVP co-culture/serum and IVP SOF calves) and in semi-standardized conditions (Study 2b, comparing MOET, IVP co-culture/serum and IVP SOF calves at one herd). In Study 2a, although IVP SOF calves showed (non-significant) shorter gestations, easier calvings and lower percentages of perinatal mortality and congenital malformations than IVP co-culture calves, birth weights were not decreased. In Study 2b however, the difference between IVP co-culture and IVP SOF calves in birth weight and ease of calving was significant (P < 0.05), IVP SOF calves resembling MOET calves more. IVP calves differed significantly from MOET calves with respect to several physiological parameters, such as blood oxygen saturation level, heart beat frequency and some measures of the heart. In addition, in Study 2b, recipients receiving an IVP SOF embryo showed a more regular return to estrus than those receiving an IVP co-culture embryo. From Study 2 it can be concluded that using a semi-defined medium for in vitro culture (SOF) may improve characteristics of IVP calves born.

Animals↗
PubMed1997

Mapping of 34 minisatellite loci resolved by two-dimensional DNA typing.

Two-dimensional (2-D) DNA typing is based on electrophoretic separation of genomic DNA fragments in two dimensions according to independent criteria (size and base-pair sequence), followed by hybridization analysis using multilocus probes. The technique allows simultaneous visualization of several hundred loci as spots in a 2-D pattern. The majority of the loci resolved are polymorphic. Using linkage analysis in a large CEPH family, this study reports the mapping of 34 loci detected by the minisatellite core probe 33.6. By multipoint linkage analysis, regional chromosome positions of the 33.6 loci could be deduced, showing no evidence of clustering. In the analysis of spot patterns, use was made of a computerized image analysis system specifically designed for 2-D DNA typing. Since experimental variations between different separation patterns were automatically corrected for with this program, rapid and reliable scorings could be obtained. The results presented demonstrate the availability of reliable genetic information throughout the 2-D separation pattern. Adding the use of semiautomated computerized pattern analysis, this study further substantiates the applicability of 2-D DNA typing in genome scanning, not only in theoretical but also in practical terms. Moreover, it can be anticipated that this method will have a specific advantage in studies that scan for trinucleotide repeat expansions and somatic instability, where the repeat sequences detected by appropriate core probes are of particular interest.

Chromosome Mapping↗
PubMed1996

Comprehensive and accurate mutation scanning of the CFTR gene by two-dimensional DNA electrophoresis.

The large number of possible disease-causing mutations in the 27 exons of the cystic fibrosis transmembrane conductance regulator (CFTR) gene has severely limited direct diagnosis of cystic fibrosis (CF) patients and carriers by mutation detection. Here we show that in principle testing for mutations in the CFTR gene can be both substantially facilitated and made virtually complete, by two-dimensional DNA electrophoretic separation of polymerase chain reaction (PCR) amplified exons on the basis of size and basepair sequence in denaturing gradient gels. Under a single optimized set of conditions we were able to obtain a pattern of spots representing all 27 exons of the CFTR gene and to readily detect 17 out of 17 identified sequence variations in 9 different exons in DNA from 11 CF patients and carriers. Our results demonstrate the potential of 2-dimensional DNA electrophoresis for comprehensive mutation analysis of the CFTR gene. The approach serves as a model for comprehensive diagnosis of the many other large disease genes for which a variety of mutations have also which been reported.

Cystic Fibrosis↗
PubMed1995

Two-dimensional DNA typing of human pedigrees: spot pattern characterization and segregation.

By two-dimensional (2-D) genome typing, i.e., electrophoretic separation of restriction enzyme-digested genomic DNA on the basis of both size and sequence in denaturing gradient gels followed by hybridization analysis, several hundred alleles (spots) can be analyzed in parallel, using a micro- or minisatellite core probe. We studied the segregation of 213 and 214 spots detected by microsatellite core probe (CAC)n and minisatellite core probe 33.6, respectively, in two three-generation human pedigrees. Reproducibility of the spot patterns was such that particular spot variants could be scored in both pedigrees. Between 73 and 74% of the spots scored were variant and were transmitted in a Mendelian manner. Very little cosegregation among the 2-D spots themselves was observed, suggesting a random distribution over the genome. Several pairs of spots that appeared to contain both alleles from single loci were identified. The few spots detected by both probes (overlapping spots) showed different segregation patterns, indicating that each probe detects independent sets of genetically informative loci. These results provide a firm basis for using 2-D DNA typing to identify disease loci and for constructing a 2-D spot genetic linkage map of the human genome.

Alleles↗
PubMed1995

Two-dimensional DNA typing as a genetic marker system in humans.

By two-dimensional (2-D) DNA typing several hundred genomic loci can be analysed simultaneously in a two-dimensional pattern as spots detected by micro- or minisatellite core probes. Many of these loci display DNA sequence polymorphisms, and we have examined whether it is possible to extract genetic information from the rather complex but potentially very informative 2-D DNA typing patterns. To do so, the segregation of 9 spots detected by the microsatellite core probe (CAC)n was followed in a large CEPH pedigree, and by linkage analysis it was possible to obtain chromosomal assignments of the corresponding (CAC)n loci in all cases except one. Furthermore, a regional, physical localization of these loci emerged from analysis of the existing genetic and physical localization data of DNA markers flanking the (CAC)n loci. We have hereby obtained evidence that the spots detected by the microsatellite core probe (CAC)n segregate in a Mendelian manner and that it is possible to reliably score the segregation of single spots within a family. These results indicate that the large amount of potential information inherent in 2-D DNA typing may be used as a genetic marker system; an important prerequisite for its application as a genome scanning method, e.g. in detection of genomic alterations in cancer and in mapping of genetic traits.

Chromosome Mapping↗
PubMed1994

Two-dimensional DNA electrophoresis in mutation detection.

Accurate detection of gene mutations is important in many areas of biology and medicine. In fundamental studies of mutagenesis it is often necessary to assess all possible mutations, either spontaneous or induced by genotoxic agents, in a particular gene or gene sequence to explain a given cellular or physiological endpoint. In molecular medicine comprehensive detection of all possible mutations in a disease gene is required before clinical genetic testing becomes feasible. Of the many mutation detection methods currently available none is capable of scanning for all possible mutations in a cost-effective manner. Here we show that by two-dimensional DNA electrophoretic separation, on the basis of both size and base pair sequence, in principle all mutations in a given gene can be detected. This is illustrated by some data on 2-D electrophoresis of 10 exons of the cystic fibrosis gene.

Cystic Fibrosis↗
PubMed1994

Genome scanning of breast cancers by two-dimensional DNA typing.

We have recently used two-dimensional DNA typing to detect genetic alterations in breast tumours. This method, which is based on size separation in neutral gels and sequence separation in denaturing gradient gels followed by hybridisation analysis with mini- and microsatellite core probes, allows the simultaneous analysis of hundreds of allelic fragments in a very short time. Here we demonstrate the potency of this method for total genome scanning of the tumour genome by analysing a small series of breast cancers. Comparison of tumour and normal DNA from ten breast cancer patients, using two-dimensional DNA typing with four core probes, revealed a considerable number of genomic alterations. In contrast, with Southern blot analysis only a few alterations were observed using the same probes. Most of the changes observed (74%) were deletions (absence of spots in the tumour) while 20% corresponded to amplifications (spots of higher intensity in the tumour) and 5% were new spots (gains). About 10% of the genomic changes detected appeared to occur in the tumours of more than one patient.

Base Sequence↗
PubMed1993

Parallel genome analysis by two-dimensional DNA typing.

By two-dimensional (2-D) DNA typing a restriction enzyme digest of genomic DNA can be resolved on the basis of both size and base-pair sequence and subsequently analysed by repeat probe hybridization to reveal sequence variants at multiple genomic sites in parallel. The system has been partly automated and allows for large-scale comparative analysis of complex genomes in a cost-effective manner.

Automation↗
PubMed1993

Genome scanning of human breast carcinomas using micro- and minisatellite core probes.

We have analyzed tumor and lymphocyte DNA from six breast cancer patients by one- and two-dimensional DNA fingerprinting using micro- and minisatellite core probes to estimate the extent and nature of DNA alterations in tumors. Both approaches were compared regarding sensitivity in genome analysis. We find that the number of deletions and amplifications increases linearly with the number of restriction fragments analyzed using the two-dimensional approach, as compared with the number found using the more traditional one-dimensional method. A set of four micro- and minisatellite core probes resulted in a total number of approximately 70 bands per patient using one-dimensional analysis of RsaI-digested DNA. When the same DNA was analyzed with the two-dimensional approach about 300 analyzable spots were resolved. In one patient, the tumor DNA contained 11 amplified spots and 14 deleted spots when compared to the patients lymphocyte DNA. Using HaeIII-digested DNA, a maximum of 845 spots could be observed, with only three probes.

Adult↗
PubMed1993

Linkage analysis by two-dimensional DNA typing.

In two-dimensional (2-D) DNA typing, genomic DNA fragments are separated, first according to size by electrophoresis in a neutral polyacrylamide gel and second according to sequence by denaturing gradient gel electrophoresis, followed by hybridization analysis using micro- and minisatellite core probes. The 2-D DNA typing method generates a large amount of information on polymorphic loci per gel. Here we demonstrate the potential usefulness of 2-D DNA typing in an empirical linkage study on the red factor in cattle, and we show an example of the 2-D DNA typing analysis of a human pedigree. The power efficiency of 2-D DNA typing in general is compared with that of single-locus typing by simulation. The results indicate that, although 2-D DNA typing is very efficient in generating data on polymorphic loci, its power to detect linkage is lower than single-locus typing, because it is not obvious whether a spot represents the presence of one or two alleles. It is possible to compensate for this lower informativeness by increasing the sample size. Genome scanning by 2-D DNA typing has the potential to be more efficient than current genotyping methods in scoring polymorphic loci. Hence, it could become a method of choice in mapping genetic traits in humans and animals.

Alleles↗
PubMed1991

Induction and disappearance of DNA strand breaks in human peripheral blood lymphocytes and fibroblasts treated with methyl methanesulfonate.

The induction and disappearance of DNA single-strand breaks (SSB) in human peripheral blood lymphocytes (PBL) and fibroblasts exposed to methyl methanesulfonate (MMS) were investigated by using the alkaline filter elution assay. In the two cell types, identical amounts of SSB were induced during a 45-min treatment with a given dose of MMS. In quiescent PBL only 9 +/- 4% (mean +/- SD) of the induced SSB had disappeared at 1 h after exposure, whereas in phytohemagglutinin-stimulated PBL, 23 +/- 12% disappeared within the same repair period. The percentage SSB disappearance in confluent fibroblasts was 25 +/- 2% at 1 h after exposure. As in PBL, the percentage SSB disappearance in fibroblasts appeared to be proliferation-dependent; actively dividing fibroblasts removed 50 +/- 12% of the MMS-induced SSB during the 1-h repair period. The accumulation of SSB in PBL, but not in fibroblasts, during MMS exposure in the presence of the excision-repair inhibitor 1-beta-D-arabinofuranosylcytosine indicated the utilization of different repair pathways in these two cell types. The generally lower rate of disappearance of MMS-induced SSB in PBL as compared to fibroblasts correlated with an increased loss of cell viability, measured by determining the incorporation of [3H]thymidine.

Cell Division↗
PubMed1991

Induction and disappearance of DNA strand breaks and/or alkali-labile sites in human lymphocytes exposed to N-ethyl-N-nitrosourea.

We investigated the induction and disappearance of DNA lesions that are detected as single-strand breaks (SSBs) with the alkaline filter elution technique, in human peripheral blood lymphocytes (PBLs) following exposure to N-ethyl-N-nitrosourea (ENU). In PBLs of the 15 individuals studied, 35 +/- 16% (mean +/- SD) of the SSBs present at the end of a 20 min treatment disappeared within 1 h; up to 24 h post-treatment no further disappearance was observed. Interindividual differences in SSB disappearance were considerable; in two cases, almost no SSBs disappeared over the 1 h period. In PBLs of the same 15 individuals 85 +/- 3% (mean +/- SD) of the SSBs induced by 4 Gy of gamma-rays were found to disappear within 1 h, which indicated no interindividual differences. Multiple blood sampling at 1 month intervals indicated that interindividual differences in ENU-induced SSB repair are constant and do not vary with time. The low rate of SSB disappearance appeared to correlate with low cell survival after ENU exposure, measured as a reduction in phytohemagglutinin-stimulated incorporation of [3H]-thymidine. The cytosine analog 1-beta-D-arabinofuranosyl-cytosine completely inhibited SSB disappearance, indicating that the removal of the repairable ENU-induced SSBs involves excision repair events.

Cell Survival↗
PubMed1990

Spontaneous DNA breaks in the rat brain during development and aging.

The level of spontaneous DNA breaks in nuclei isolated from the cerebral cortex of rat embryos at 12, 15 and 19 days of gestation, and from cerebral cortex and cerebellum of 24-day-, 6-month- and 36-month-old rats was measured by alkaline elution. A constant low level of DNA breaks was found in brain DNA during development from an embryo at day 12 of gestation to a 24-day-old rat. During aging the level of DNA breaks remained at the same low level, as shown by comparing nuclei from the cerebral cortex and cerebellum of 6- and 36-month-old animals. By contrast, an almost 2-fold increase in the level of DNA breaks was observed in rat liver nuclei between 6 and 36 months of age, confirming our earlier findings on isolated liver cells. Although there were no changes in the level of DNA breaks in rat brain during development or during aging, breaks accumulated rapidly post mortem. The rate of this process was not age-dependent. Our data suggest that the level of spontaneous DNA breaks in the brain is not likely to be of fundamental importance in the complex cellular alterations associated with brain development and aging.

Aging↗