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J Dean

Publications and source records attributed to J Dean.

At least 127 records · Page 7Linked to original sources
PubMed1987

Oocyte-specific expression and developmental regulation of ZP3, the sperm receptor of the mouse zona pellucida.

The mouse zona pellucida is composed of three sulfated glycoproteins, encoded by the oocyte genome, that have important biological functions in preimplantation development. One of the zona gene products, ZP3, functions as the sperm receptor at fertilization. Our present data demonstrate that the ZP3 gene is transcribed in oocytes where its expression is developmentally regulated. Resting primordial oocytes do not express ZP3 mRNA, but these transcripts rapidly accumulate in growing oocytes so that they represent 0.1-0.2% of the total poly(A+) RNA. As oocytes complete their growth and undergo meiotic maturation, the abundance of ZP3 transcripts falls off dramatically; ovulated eggs contain less than 15% of peak levels. The oocyte-specific accumulation of ZP3 transcripts serves as an attractive system for further studies of factors that modulate developmentally regulated genes during mammalian oogenesis.

Animals↗
PubMed1986

Effects of anti-zona pellucida monoclonal antibodies on fertilization and early development.

The murine zona pellucida surrounds the growing oocyte, ovulated egg and dividing embryo. It is comprised of three sulfated glycoproteins designated ZP-1, ZP-2, and ZP-3 which have molecular weights of 185,000, 140,000 and 83,000 daltons respectively. We have isolated a series of cell lines that produce monoclonal antibodies to ZP-2 and to ZP-3. These immunogical probes indicate that the extracellular matrix proteins of the zona pellucida are found uniquely in the ovary where they surround maturing oocytes. We have demonstrated that passive immunization with antibodies specific either for ZP-2 or ZP-3 inhibit in vivo and in vitro fertilization. This effect is observed with ng/ml quantities of antibody. It appears that the antibodies do not preclude sperm binding but rather prevent sperm penetration of the zona by steric hinderance. Although long-term, the contraceptive effect is fully reversible and this reversibility is associated with loss of antibody from the zona pellucida surrounding intra-ovarian oocytes. Antibodies to ZP-2 or ZP-3 had no other adverse effect on in vivo or in vitro preimplantation development.

Animals↗
PubMed1986

Oocyte-specific gene expression: molecular characterization of a cDNA coding for ZP-3, the sperm receptor of the mouse zona pellucida.

The mouse zona pellucida genes are expressed uniquely during oogenesis and are developmentally regulated in the absence of cell division. Little is known about the mechanisms that control the expression of these germ-line-specific genes that play crucial roles in early mammalian development. We have constructed a lambda gt11 cDNA library from ovarian poly(A)+ mRNA and have isolated clones coding for ZP-3, the mouse sperm receptor. The identity of the clones was confirmed by comparing their DNA sequence with an amino acid sequence obtained from an isolated ZP-3 peptide. The ZP-3 gene is transcribed as a 1.7-kilobase poly(A) mRNA that is detected exclusively in ovarian tissue. This germ-line-specific expression is reflected in the observed hypomethylation of the ZP-3 locus in ovarian but not liver or brain DNAs. The ZP-3 gene is otherwise identically organized in somatic and germ-line DNA where it appears to be present as a low-copy-number or single-copy gene. Despite the fact that the mouse sperm receptor demonstrates species specificity, the ZP-3 cDNA cross-hybridized with DNA from a variety of mammalian species, including rat, rabbit, dog, pig, cow, and human.

Animals↗
PubMed1985

Monoclonal antibodies to the murine zona pellucida protein with sperm receptor activity: effects on fertilization and early development.

During development and maturation, mammalian oocytes are surrounded by the zona pellucida which in the mouse is comprised of three sulfated glycoproteins, ZP-1, ZP-2, and ZP-3. Previously, monoclonal antibodies to ZP-2 have been isolated. The isolation and characterization of monoclonal antibodies specific for ZP-3, the zona protein with sperm receptor activity are now reported. Following passive immunization, these monoclonal antibodies localize to the intraovarian zonae pellucidae and their presence precludes both in vivo and in vitro fertilization of subsequently ovulated eggs. Monoclonal antibodies specific for either ZP-2 or ZP-3 also completely block in vitro fertilization at relatively low concentration ranging from 0.4 to 75 micrograms/ml. The contraceptive effect requires the presence of the zona and appears to inhibit the penetration of the zona pellucida by sperm rather than by blocking the sperm binding site. Neither antibody interferes with in vitro development from the two-cell to the blastocyst stage or with subsequent hatching from the enveloping zona pellucida.

Animals↗
PubMed1985

The responses of rats to various combinations of energy and protein. II. Diets made from natural ingredients.

Natural diets with metabolizable energy levels of 8.5, 10.0, 11.5 or 13.0 MJ/kg and protein:energy ratios of 1:1, 1.33:1, 1.67:1 or 2:1 %:MJ/kg were fed ad libitum for 28 days to male and female weanling rats. Records of food intake and bodyweight were maintained weekly, and at post mortem examination body length, abdominal fat, liver and kidney weights were measured. Food intake was reduced when dietary energy level increased but this reduction was not sufficient to prevent energy intake increasing, especially in males. Female rats showed only small increases in energy intakes as dietary energy levels rose. The increase in energy intake at higher dietary energy levels increased food conversion efficiency, weight gain and abdominal fat deposition. The responses of male rats were greater than females. Protein intake had a smaller and less consistent effect than energy intake. Increased protein:energy ratio resulted in higher absolute and relative liver and kidney weights and greater body length. This reflected the increase of bodyweight gain at higher protein:energy ratios.

Adipose Tissue↗
PubMed1985

The availability to the rat of energy from various diet ingredients.

The digestible and metabolizable energy values of 8 ingredients commonly used in laboratory animal diets were determined using the growing male rat, by the total collection method. Each ingredient was incorporated into a basal diet of maize, wheat, soyabean meal and fishmeal. The metabolizable energy values, on a dry matter basis, corrected to the nitrogen retention of the basal diet for rats per 100 g bodyweight were as follows: maize 15.23 MJ/kg, extracted soyabean meal 14.11 MJ/kg, barley 12.31 MJ/kg, wheat 14.09 MJ/kg, oatfeed 1.36 MJ/kg, white fishmeal 11.61 MJ/kg, dried skimmed milk 14.32 MJ/kg, casein 17.91 MJ/kg. Additional analytical data for the 8 ingredients are also given.

Animal Nutritional Physiological Phenomena↗
PubMed1985

The responses of rats to various combinations of energy and protein. I. Diets made from purified ingredients.

Male and female weanling rats were fed ad libitum for 28 days on purified diets with metabolizable energy levels of 8.0, 9.5, 11.0 or 12.5 MJ/kg and protein:energy ratios of 1:1, 1.33:1, 1.67:1 or 2:1 %:MJ/kg at each energy level. Major nutrients were balanced in proportion to energy and protein. The following parameters were measured: food intake, bodyweight, body length, abdominal fat, liver and kidney weights. Increasing dietary energy level reduced food intake but the reduction was not sufficient to prevent an increase in energy intake. This was reflected by increases in bodyweight, body length, abdominal fat, and relative liver and kidney weights, especially in male rats. Higher energy intake increased weight gain and food conversion efficiency to a greater extent than higher protein intake. The response to protein intake at different energy levels was not consistent. There was no common protein:energy ratio for overall good performance. It is concluded that rat growth and other features can be controlled by the alteration of dietary energy and protein levels.

Adipose Tissue↗
PubMed1985

The nutritional value of rat diets of differing energy and protein levels when subjected to physical processing.

4 diets formulated to contain 8.5, 10.0, 11.5 and 12.5 MJ/kg metabolizable energy and 85, 133, 192 and 250 g/kg of protein respectively were prepared in 3 physical forms: meal, reground pellets or reground expanded and fed to growing rats from 28 to 56 days of age. Food intake was increased by pelleting and expanding in lower energy diets, whereas these differences tended to disappear in the higher energy diets. Growth and food conversion efficiencies showed a similar pattern, with the greatest differences evident in the low energy diets. Male rats showed greater differences than females in all parameters measured. Expanding the diet improved the microbiological status over pelleting both being superior to unprocessed meal. Measurements of digestible and metabolizable energy values of the 8.5 and 12.5 MJ/kg diets revealed consistent decreases in energy availability following processing. This suggested that the observed growth responses were due mainly to increased food intake coupled with increased nitrogen retention.

Animal Feed↗
PubMed1985

A multivariant assessment and treatment technique for alcohol problems.

Traditional alcohol treatment systems employ a binary procedure in the assessment and treatment of alcohol problems. The binary approach has come under critical review and an alternative multivariant approach has been suggested. The purpose of this paper is to propose a multivariant design developed in clinical practice. The goals of the presentation are to stimulate concern for multivariant techniques and to assess their impact on treatment outcome.

Alcohol Drinking↗
PubMed1984

Scintigraphy of normal mouse ovaries with monoclonal antibodies to ZP-2, the major zona pellucida protein.

The zona pellucida is an extracellular glycocalyx, made of three sulfated glycoproteins, that surrounds mammalian oocytes. Parenterally administered monoclonal antibodies specific for ZP-2, the most abundant zona protein, localize in the zona pellucida. When labeled with iodine-125, these monoclonal antibodies demonstrate a remarkably high target-to-nontarget tissue ratio and provide clear external radioimaging of ovarian tissue.

Animals↗
PubMed1984

Monoclonal antibodies to the major protein of the murine zona pellucida: effects on fertilization and early development.

The growing murine oocyte is surrounded by an extracellular zona pellucida consisting of three sulfated glycoproteins, ZP-1, ZP-2, and ZP-3. The smallest of these, ZP-3, has been reported to be the species-specific sperm receptor. Monoclonal antibodies have been recently characterized to three different antigenic determinants, two found exclusively on ZP-2, and one found on both ZP-2 and ZP-3. The in vivo effect of these antibodies on the three known functions of the zona pellucida were examined. The most dramatic effect was the prevention of fertilization. After administration, the monoclonal antibodies were located in the ovary on the zona pellucida of growing oocytes. Eggs ovulated subsequently were coated with the monoclonal antibodies and failed to develop into 2-cell embryos after mating. Eighty days later, the monoclonal antibodies could no longer be detected on the zona of ovarian oocytes, and this loss coincided with the resumption of fertility. These findings provide molecular evidence for the hypothesis that the immunological block to sperm-egg binding need not involve antibody specific for the sperm receptor, and that antibodies to the zona pellucida block sperm access by steric hinderance. Other known functions of the zona were unaffected. The antibodies were unable to induce the biochemical changes in the zona associated with the postfertilization block to polyspermy and had no detectable effect on preimplantation development.

Animals↗
PubMed1984

Monoclonal antibodies as probes of the distribution of ZP-2, the major sulfated glycoprotein of the murine zona pellucida.

Three sulfated glycoproteins (ZP-1, ZP-2, and ZP-3) make up the zona pellucida, an extracellular glycocalyx that surrounds mouse oocytes. We have produced five monoclonal antibodies specific to the zona. All five immunoprecipitated ZP-2, and in addition, two of the antibodies immunoprecipitated ZP-3. This suggests the presence of either a common antigenic site or one made up in part by each of the two glycoproteins. The monoclonal antibodies bound to approximately 1.3 X 10(8) binding sites per ovulated mouse egg which represents 2% of the total number of ZP-2 molecules present in the zona. ZP-2 appeared to be present throughout the zona and indirect immunofluorescence revealed a fibrous pattern with no evidence of localization. Furthermore, this pattern of distribution, which was identical for all five monoclones, remained constant after fertilization at the two-cell embryo stage. Laser photobleaching demonstrated that ZP-2 is stably integrated in the extracellular matrix of the zona pellucida. No mouse tissue other than the ovary contained ZP-2 and ZP-2 is antigenically distinct from other previously described extracellular matrix proteins.

Animals↗
PubMed1983

In vitro biosynthesis of three sulfated glycoproteins of murine zonae pellucidae by oocytes grown in follicle culture.

The zona pellucida is an extracellular glycocalyx that surrounds the growing oocyte and mediates specific biological functions essential to early mammalian development. We have isolated by a novel technique intact zonae pellucidae from a murine follicle culture system which mimics in vivo granulosa cell-oocyte interactions. Using radioactive precursors we have demonstrated that all three zona proteins, ZP-1, ZP-2, and ZP-3, are sulfated glycoproteins. Incubation of the follicle culture with tunicamycin (0.5 microgram/ml), an antibiotic that blocks N-glycosylation, inhibits new protein deposition in the zona. Under these same conditions overall protein synthesis is decreased only 30%. Biosynthetic studies indicate that after 6 days in culture the zona proteins are produced at 0.4 pg/oocyte/h, which represents 2-3% of the total oocyte protein synthesis. This synthesis stops at or before ovulation and the extremely long half-life (greater than 100 h) of the zona may be essential to preserve its known biological functions, all of which occur after ovulation.

Animals↗
PubMed1983

Decondensation of mouse sperm chromatin and reassembly into nucleosomes mediated by polyglutamic acid in vitro.

The organization of the mammalian sperm nucleus was probed with staphylococcal nuclease. Although isolated nuclei are resistant to cleavage, following reduction and alkylation, 30% of the sperm DNA could be digested and the remaining DNA had a heterodisperse size distribution. By morphological criteria, a model acidic protein, polyglutamic acid was capable of decondensing purified sperm nuclei that had been reduced and alkylated. The maximal extent of nuclease digestion increased to 85-90%. The subsequent addition of purified, exogenous core histones in 0.1 M NaCl partially reversed this vulnerability to nuclease cleavage such that only 55% of the DNA was digested. Furthermore, analysis of the remaining DNA revealed a nucleosome ladder pattern with unit length repeat of 150 bp. These results strongly suggest that polyglutamic acid can mediate not only decondensation of sperm nuclei but also the assembly of sperm chromatin into nucleosomes.

Alkylation↗
PubMed1983

Preimplantation development: biology, genetics, and mutagenesis.

After fertilization, the one-cell zygote grows to the morula stage and then the blastocyst stage prior to its implantation in the uterus. This series of events is under the control of the embryonic genome, although maternal cytoplasmic components may initially play a major role. The study of molecular biology has revealed a great deal concerning the organization and expression of the eukaryotic genome. Particular interest has been focused on the mechanism of control of gene expression. These mechanisms must ultimately control cellular differentiation and the early development of the embryo. The study of reproductive toxicology requires a sound molecular appreciation of gene expression and cell differentiation. Mutations of the genome can dramatically affect the embryo. Although repair mechanisms have evolved to compensate for these mutations, repairs are not uniformly successful and unrepaired mutations can lead to early fetal loss.

Animals↗