Coordinate expression of the three zona pellucida genes during mouse oogenesis

The mammalian zona pellucida is an extracellular matrix that surrounds growing oocytes, ovulated eggs and early embryos. The mouse zona is composed of three sulfated glycoproteins: ZP1, ZP2 and ZP3. Each is critically involved in fertilization, the postfertilization block to polyspermy and protection of the preimplantation embryo. We have previously isolated cDNAs encoding mouse ZP2 and ZP3 and now report the isolation of a full-length cDNA encoding ZP1. Mouse ZP1 is composed of a 623 amino acid polypeptide chain with a signal peptide and a carboxyl terminal transmembrane domain, typical of all zona proteins. Sequence comparison demonstrate that mouse ZP1 is an orthologue of a rabbit zona protein, R55. The expression of R55 has been reported previously in both oocytes and granulosa cells. However, by northern analysis and in situ hybridization with 33P-labelled antisense probes to each of the three mouse zona mRNAs, we have determined that the expression of each mouse zona gene is restricted to the oocyte. ZP2 transcripts, but not ZP1 or ZP3, are detected in resting (15 microns diameter) oocytes, and all three zona transcripts coordinately accumulate as oocytes begin to grow. Together they represent approximately 1.5% of the total poly(A)+ RNA in 50–60 microns oocytes. In the latter stages of oogenesis, their abundance declines and each zona transcript is present in ovulated eggs at less than 5% of its maximal level. No zona transcripts were detected above background signal in granulosa cells. We conclude that, in mice, the three zona pellucida genes are expressed in a coordinate, oocyte-specific manner during the growth phase of oogenesis. Our data support the hypothesis that the transcription of the zona genes is controlled, in part, by shared regulatory element(s).

The covalently closed duplex form of the hepadnavirus genome exists in situ as a heterogeneous population of viral minichromosomes

Replication of hepadnaviruses requires a persistent population of covalently closed circular (CCC) DNA molecules in the nucleus of the infected cell. It is widely accepted that the vital role of this molecule is to be the sole DNA template for the synthesis by RNA polymerase II of all viral transcripts throughout the infection process. Since the transcriptional activity of eukaryotic nuclear DNA is considered to be determined in part by its specific organization as chromatin, the nucleoprotein disposition of the hepadnavirus CCC DNA was investigated. These studies were undertaken on the duck hepatitis B virus (DHBV) CCC DNA present in the liver cell nuclei of DHBV-infected ducks. The organization and protein associations of the DHBV CCC DNA in situ were inferred from sedimentation, micrococcal nuclease digestion, and DNA superhelicity analyses. These three lines of investigation demonstrate that the DHBV CCC DNA is stably associated with proteins in the nuclei of infected liver cells. Moreover, they provide compelling evidence that the viral nucleoprotein complex is indeed a minichromosome composed of classical nucleosomes but in arrays that are atypical for chromatin. When the DHBV chromatin is digested with micrococcal nuclease, a ladder of viral DNA fragments that exhibits a 150-bp repeat is produced. This profile for the viral chromatin is obtained from the same nuclei in which the duck chromatin shows the standard 200-bp ladder. The superhelicity of the DHBV CCC DNA ranges from 0 to 20 negative supertwists per molecule, with all possible 21 topoisomers present in each DNA preparation. The 21 topoisomers of DHBV CCC DNA are inferred to derive from an identically diverse array of viral minichromosomes. In the DHBV minichromosomes composed of 20 nucleosomes, 96.7% of the viral DNA is calculated to be compacted into these chromatin subunits spaced on average by 5 bp of linker DNA; other minichromosomes contain fewer nucleosomes and proportionately more linker DNA. Two major subpopulations of DHBV minichromosomes are detected with comparable prevalence. The two groups correspond to minichromosomes which contain essentially a full or half complement of nucleosomes. The functional significance of this minichromosome diversity is unknown but is suggestive of transcriptional regulation of the viral DNA template.

Reversion of duck hepatitis B virus DNA replication in vivo following cessation of treatment with the nucleoside analogue ganciclovir

In order to define, in more detail, the virological events which occur after completion of antiviral chemotherapy, ducks congenitally infected with the duck hepatitis B virus (DHBV) were treated for 4 weeks with the nucleoside analogue ganciclovir and followed up over a 7-day period. Specimens of serum and liver were collected daily during follow-up for virological analysis. Treatment resulted in a substantial reduction in both viraemia and liver DHBV DNA replicative intermediates. However, after cessation of treatment, viraemia returned to detectable levels within 4 days. In the liver, the viral supercoiled DNA (SC DNA) was the form least affected by therapy and returned to near control levels by day 2 post-treatment. The other hepatic replicative intermediates reached pretreatment levels within 4 days of cessation of therapy. This study has defined the kinetics of relapse of viral replication after completion of antiviral therapy in the duck hepatitis B model. Of all viral replicative forms, the SC DNA appears to be the one which is most resistant to nucleoside analogue therapy and is presumably responsible for the relapse phenomenon observed post-treatment.

Effect of treatment with a hydroxymethylglutaryl coenzyme A reductase inhibitor on fasting and postprandial plasma lipoproteins and cholesteryl ester transfer activity in patients with NIDDM

Patients with non-insulin-dependent diabetes mellitus (NIDDM) have a greater risk of developing coronary heart disease than would be expected from a similar degree of hyperlipidemia in nondiabetic populations. Accelerated transfer of cholesteryl esters (CET) from high-density lipoprotein (HDL) to low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL), a process that is associated with atherosclerosis, may be a possible explanation for this. CET, plasma lipoprotein concentration, and mass in the fasting and postprandial state have been examined in 31 hyperlipidemic patients with NIDDM before and after 8 weeks of treatment with the hydroxymethylglutaryl (HMG)-coenzyme A (CoA) reductase inhibitor pravastatin in a double-blind, placebo-controlled, parallel group study. Body mass index, glycemic control, and blood pressure remained unaltered during the study period. Compared with placebo, pravastatin decreased fasting serum cholesterol (P < 0.001) and LDL cholesterol (P < 0.002) levels. The high basal CET (34.4 +/- 13.1 nmol.ml-1.h-1) was decreased significantly by pravastatin treatment (27.5 +/- 13.7 nmol.ml-1.h-1, P = 0.013). There was a fall in the total cholesterol, free cholesterol, and phospholipid content of the Sf 0-12, 20-60, and 60-400 lipoproteins (all P = 0.001). Lecithin: cholesterol acyl transferase activity was not altered. The postprandial increase in VLDL cholesterol 5 h after a standardized mixed meal was attenuated after pravastatin treatment (P = 0.011). Inhibition of hepatic cholesterol synthesis with an HMG-CoA reductase inhibitor in hyperlipidemic patients with NIDDM decreased serum cholesterol content of triglyceride-rich lipoprotein, thereby decreasing the transfer of cholesteryl ester from HDL to LDL and VLDL.

Aortic distensibility and stiffness index measured by magnetic resonance imaging in patients with Marfan's syndrome

OBJECTIVES

To use magnetic resonance imaging to measure the elastic properties of the aorta of adults with Marfan's syndrome and to compare these results with those obtained by echocardiography.

PATIENTS AND METHODS

12 patients with Marfan's syndrome and 12 controls matched for age. Transverse luminal areas of the ascending and descending aorta were measured using electrocardiographic gated magnetic resonance imaging. Echocardiography was used to measure the diameter of the ascending aorta and aortic arch in patients with Marfan's syndrome. Blood pressure was measured during both scans.

RESULTS

In diastole, transverse luminal areas of the ascending and descending aorta were significantly greater in patients with Marfan's syndrome when measured by magnetic resonance imaging and corrected for body surface area; P < 0.02 and P < 0.05 respectively. Patients with Marfan's syndrome had a higher stiffness index (112.77 v 5.78, P < 0.05) and a lower distensibility (0.0066 v 0.0105, P < 0.05) than controls. Results produced by MRI and echocardiography were not significantly different.

CONCLUSIONS

Magnetic resonance imaging gives good quality reproducible images of the ascending and descending aorta. In patients with Marfan's syndrome, aortic distensibility and stiffness index measured by magnetic resonance imaging were abnormal (but did not always relate directly to the size of the aorta.

POM-ZP3, a bipartite transcript derived from human ZP3 and a POM121 homologue

Human POM-ZP3 is a novel bipartite RNA transcript that is derived from a gene homologous to rat POM121 (a nuclear pore membrane protein) and ZP3 (a sperm receptor ligand in the zona pellucida). The 5' region is 77% identical to the 5' end of the coding region of rat POM121 and appears to represent a partial duplication of a gene encoding a human homologue of this rodent gene. The 3' end of the POM-ZP3 transcript is 99% identical to ZP3 and appears to have arisen from a duplication of the last four exons (exons 5-8) of ZP3. Using Northern blots and RT-PCR, POM-ZP3 transcripts were detected in human ovaries, testes, spleen, thymus, lymphocytes, prostate, and intestines. The longest open reading frame encodes a conceptual protein of 210 amino acids, the first 76 of which are 83% identical to residues 241-315 of rat POM121. The next 125 amino acids are 98% identical to residues 239-363 of the 424-amino-acid human ZP3 protein. By fluorescence in situ hybridization, genomic fragments of ZP3 and a human homologue of POM121 were localized to chromosome 7q11.23. Taken together, these data suggest that partial duplications of human ZP3 and a POM121-like gene have resulted in a fusion transcript, POM-ZP3, that is expressed in multiple human tissues.

Inhibition of zona pellucida gene expression by antisense oligonucleotides injected into mouse oocytes

During murine oogenesis, the zona pellucida proteins (ZP1, ZP2, and ZP3) are synthesized and secreted to form an extracellular matrix that surrounds the oocyte and mediates specific biological functions essential to mammalian fertilization and early development. To investigate the relationship among the zona proteins during zona matrix assembly, we have undertaken to inhibit de novo biosynthesis of specific zona proteins with antisense oligonucleotides complementary to the 5'-ends of ZP2 (nucleotide position 19-42) and ZP3 (nucleotide 21-44) mRNAs. When injected into the cytoplasm of growing mouse oocytes, the antisense oligonucleotides targeted specific zona mRNAs for degradation, as confirmed by a RNase protection assay. Individual zona pellucida protein synthesis was followed by immunoprecipitation with ZP2- and ZP3-specific monoclonal antibodies. New zona protein synthesis from the targeted mRNA was abolished, but nontargeted zona protein continued to be synthesized. Interestingly, abolishment of either ZP2 or ZP3 protein synthesis prevented the incorporation of the other protein into the extracellular zona matrix. These results suggest that ZP2 and ZP3 proteins are independent of each other in their biosynthesis but are dependent upon each other for their incorporation into the zona pellucida matrix. This study provides an experimental system in which destruction of a targeted mRNA generates a transient loss-of-expression phenotype during mouse oocyte growth.

A modular artificial neural net for controlling a six-legged walking system

A system that controls the leg movement of an animal or a robot walking over irregular ground has to ensure stable support for the body and at the same time propel it forward. To do so, it has to react adaptively to unpredictable features of the environment. As part of our study of the underlying mechanisms, we present here a model for the control of the leg movement of a 6-legged walking system. The model is based on biological data obtained from the stick insect. It represents a combined treatment of realistic kinematics and biologically motivated, adaptive gait generation. The model extends a previous algorithmic model by substituting simple networks of artificial neurons for the algorithms previously used to control leg state and interleg coordination. Each system controlling an individual leg consists of three subnets. A hierarchically superior net contains two sensory and two 'premotor' units; it rhythmically suppresses the output of one or the other of the two subordinate nets. These are continuously active. They might be called the 'swing module' and the 'stance module' because they are responsible for controlling the swing (return stroke) and the stance (power stroke) movements, respectively. The swing module consists of three motor units and seven sensory units. It can produce appropriate return stroke movements for a broad range of initial and final positions, can cope with mechanical disturbances of the leg movement, and is able to react to an obstacle which hinders the normal performance of the swing movement. The complete model is able to walk at different speeds over irregular surfaces. The control system rapidly reestablishes a stable gait when the movement of the legs is disturbed.

General practitioners' tacit and stated policies in the prescription of lipid lowering agents

BACKGROUND

Research into general practitioners' prescribing behaviour with regard to lipid lowering agents has relied on survey methods which presume that doctors have insight into their prescribing behaviour and can describe it accurately.

AIM

This study set out to measure the tacit policies used by general practitioners in prescribing lipid lowering agents and to compare these with their stated policies.

METHOD

Effects of 13 separate cues on decisions to prescribe were examined. The cues included cholesterol levels and a number of associated risk factors for coronary heart disease. Doctors rated 130 imaginary cases presented by a computer. Thirty five general practitioners in the Plymouth area participated in the study. Their ages ranged from 31 to 55 years and all but four were men. The raw data in each case was a rating of the likelihood that the doctor would prescribe for the patient described. These were converted into statistical weightings by use of multiple linear regression. The pattern of (standardized) weights constituted the tacit policy for each doctor. Stated policies were measured in a subsequent interview by asking doctors to rate the influence of each cue.

RESULTS

Both tacit and stated policies diverged widely between different doctors. Most doctors overestimated the number of cues that had actually influenced their decisions, and many believed that they had taken into account associated factors for coronary heart disease when they had not. On lifestyle related risks doctors were generally less likely to treat overweight people and most stated this as their policy. Most were also less likely to treat smokers but some had the opposite policy. Those less likely to treat smokers were also less likely to treat obese patients. There was also considerable variation in the extent to which the doctors took account of the attitude of the patient to receiving treatment.

CONCLUSION

Doctors' policies are highly variable and particularly inconsistent in the treatment of smokers. Relevant risk factors may be ignored--even though they are understood--because the risk assessment involved is too psychologically complex a task to be performed intuitively. Decision aids and clear protocols are needed in this area.

Effects of electrical stimulation on lymphatic flow and limb volume in the rat

BACKGROUND AND PURPOSE

The mechanism by which electrical stimulation affects edema has not been elucidated. The purpose of this study was to determine whether subcontraction high-voltage stimulation (SC-HVS) (ie, electrical stimulation that did not elicit a visible contraction) applied to the right hind limbs of rats would (1) alter the rate of lymphatic uptake of injected albumin labeled with Evans blue dye (AL-EBD) and (2) affect experimentally induced edema.

SUBJECTS AND METHODS

The paws of 28 anesthetized Sprague-Dawley rats (mean weight = 263 g, SD = 48 g) were injected with AL-EBD. The experimental group (n = 13) received 1 hour of SC-HVS, and the control group (n = 15) received sham treatment consisting of the same treatment administered to the experimental group but without the SC-HVS. Blood samples and volume measurements were obtained at intervals over a 7-hour period.

RESULTS

Analysis of variance and post hoc testing indicated that higher amounts of AL-EBD were taken up by the lymph of the experimental group animals as compared with the control group animals at each time period following the treatment. The experimental group's AL-EBD reached significance immediately after treatment, whereas the control group required an additional 4 hours. There was no significant reduction in limb volume in either group.

CONCLUSION AND DISCUSSION

The SC-HVS significantly increased the uptake of AL-EBD by lymphatic vessels, but it did not cause a significant decrease in the induced edema. The results of this study indicate that SC-HVS has the potential to reduce edema by increasing lymphatic uptake of proteins.

Intersegmental and local interneurons in the metathorax of the stick insect Carausius morosus that monitor middle leg position

1. In the stick insect, proprioceptive information from the middle leg is used to define the target for the swing movement of the adjacent rear leg ("targeting behavior"). To investigate the underlying neural circuits, intracellular recordings were made in the ganglion controlling the rear leg, the metathoracic ganglion, while systematically moving the tarsus of the middle leg. 2. Several intersegmental interneurons and one local interneuron were identified as possible contributors to the targeting behavior. The intersegmental interneurons code the position of the middle leg tarsus in a highly simplified manner: test movements of the middle leg in the dorsal, lateral, and caudal directions from the standard starting position at right angles to the thorax elicit phasic-tonic responses in three different intersegmental neurons. The response in each interneuron actually reflects the movement and position at only one joint of the middle leg: for the neurons responding primarily to movement in the caudal, dorsal, and lateral test directions, the adequate stimulus is movement at the subcoxal joint, the coxa-trochanter joint, and the femur-tibia joint, respectively. 3. The metathoracic local interneuron integrates information from ipsilateral middle and rear legs in such a way as to provide an approximate measure of the distance between the two tarsi in the longitudinal direction. It is depolarized in a phasic-tonic manner both by caudal movements of the ipsilateral middle leg and by rostral movements of the ipsilateral rear leg. The adequate stimulus in each case is the change in the angle at the subcoxal joint of the leg moved. Depolarization of this neuron activates retractor motoneurons, which is consistent with a role in terminating the swing movement. 4. Altogether the results indicate first, that the targeting behavior could be controlled by very few intersegmental channels and, second, that the nervous system encodes the position of the middle leg tarsus in terms of joint angles rather than in abstract, body-centered coordinates.

Obstetrical and gynecological complications in fragile X carriers: a multicenter study

We have conducted a multicenter obstetrical and gynecological survey of women in fragile X families. Included in the study were 131 gene carriers (39 with a full mutation and 92 with a premutation) and 109 noncarriers. Analysis indicated that higher numbers of fragile X gene carriers reported having irregular menses and other gynecological complications. As a group they also experienced cessation of menses prior to age 40 years at a significantly higher rate. The data appear to indicate that the FMR1 gene may play a role in the development and proliferation of oogonia.

Ascertainment and severity of Marfan syndrome in a Scottish population

This study in north east Scotland has shown that Marfan syndrome has a minimal birth incidence of 1:9802 live births, a minimal prevalence of 1:14217, and that 8/30 (26.7%) of cases in our series are new mutations. The calculated mutation rate is 15 +/- 6.7 x 10(-6) and there is evidence of reduced reproductive fitness.

Biology and structure of the zona pellucida: a target for immunocontraception

Although reversible interference of sperm-egg interactions with pharmacological agents has not yet been achieved, animal models have provided increasing evidence that immunological reagents directed against mammalian gametes can effectively inhibit fertilization. One potential target of immunocontraception is the zona pellucida, an extracellular matrix that surrounds the growing oocyte and ovulated egg. Recent advances in our knowledge of the biosynthesis and molecular biology of the zona pellucida have provided much information useful in the rational design of immunocontraceptive vaccines. There remain, however, major obstacles to using immunological reagents to prevent fertilization, including potential toxic side effects, the lack of adequate delivery systems and the possibility of incomplete reversibility. This review summarizes current understanding of the production of the zona pellucida during folliculogenesis, the structure of the conserved proteins and genes in the zona pellucida, and the progress made in the development of immunocontraceptive strategies that focus on this oocyte-specific structure.

Control of human arm movements in two dimensions: paths and joint control in avoiding simple linear obstacles

In order to examine path planning and the control of redundant degrees of freedom in the human arm, the movements of the shoulder, elbow and wrist were recorded as subjects moved a pointer to a target and avoided a simple obstacle. With respect to joint control, the results show that the extra degree of freedom provided by the wrist is incorporated into target movements in a systematic manner for both large and small obstacles; it is not used only when there is no geometrical alternative. For the wrist, two strategies are apparent, depending upon the length of the obstacle. Wrist extension predominates for shorter obstacles, while flexion or extension and flexion predominate for longer obstacles. These wrist movements shorten the effective length of the distal segments (lower arm plus hand and pointer) and thus reduce the excursion required at the proximal joints. In part, they correspond to assuming the most comfortable arm configuration at each point in the new path necessitated by the obstacle and can be described by static cost functions. However, wrist extension is also used to move the hand and pointer away from the obstacle as shoulder and elbow movements carry the wrist itself towards the obstacle. Wrist flexion is also used to move the pointer tip rapidly past the obstacle. These components, which cannot be explained by static cost functions alone, confirm for the human arm the hypothesized use of redundant degrees of freedom in obstacle avoidance. With respect to path planning, the results show that the minimum distance between pointer and obstacle remains fairly constant over a large range of obstacle lengths; this relative invariance is interpreted to support the hypothesis that workspace coordinates are important for movement planning. However, minimum distance and several other path parameters do depend significantly on the orientation and location of the movement in the workspace. This inhomogeneity implies that movement planning does not occur exclusively in workspace coordinates; it suggests an influence of joint space criteria. In frontal movements, for example, the systematic decline in the minimum distance with increasing obstacle length is interpreted as a compromise reducing the amount of extra joint movement and the discomfort of arm configurations.

Preimplantation diagnosis or chorionic villus biopsy? Women's attitudes and preferences

The objective of this work was to assess women's attitudes and preferences to two methods of prenatal diagnosis for genetic disease: embryo and chorionic villus biopsy (CVS). The design involved a structured postal questionnaire sent to women in the Grampian region with different reproductive experiences. The population sample included 46 women who had had genetic counselling because of a family history of a single gene disorder, 18 women who had had CVS for a single gene disorder, 158 women who had had CVS for other reasons, 200 women who had recently delivered a normal baby and 50 women who had experience of in-vitro fertilization (IVF). The main outcome measures were attitudes to family limitation, prenatal diagnosis, termination for fetal abnormality, embryo biopsy and CVS. Of the women surveyed, 38% preferred embryo diagnosis, whereas 42% favoured CVS and termination. Women with previous experience of CVS preferred this option whereas those with experience of IVF as infertility treatment were more likely to favour embryo diagnosis, as were women who had had genetic counselling for a single gene disorder. It was concluded that a substantial number of women find embryo diagnosis more acceptable than CVS when the pregnancy is at high risk. This is especially true amongst those with experience of IVF or who are at risk themselves. A demand for embryo diagnosis has been demonstrated.

Antenatal cystic fibrosis carrier screening--whether, when and how?

Population screening for carriers of cystic fibrosis (CF) is now possible. Such screening may have both advantages and disadvantages and hence must be evaluated before it becomes routine practice. As the potential benefits of screening are wide and the drawbacks may include psychological effects, a combination of approaches is needed to assess screening thoroughly instead of only counting numbers of terminations or carrier tests. We describe the issues concerned and our methodology for a rigorous evaluation of population antenatal carrier screening for cystic fibrosis.

Reduction of animal use with improved procedure for acute tolerance assessment

A retrospective evaluation of previously conducted acute tolerance tests in rats and mice, following oral and intravenous routes of administration, and a review of the literature indicated that a minimum of three animals per group was adequate to characterize acute tolerance. Limited exploratory testing, using six compounds for which classical LD50 tests had been performed previously, indicated that fewer numbers of rats gave comparable results. A method is proposed by which the acute tolerance of a compound may be adequately characterized in both sexes using approximately 30 animals instead of the 70 to 100 used in the classical LD50 test. The objective of the testing procedure is identification of the maximum nonlethal dose or the minimum lethal dose, rather than determination of the LD50.

Control of Three- and Four-Joint Arm Movement: Strategies for a Manipulator With Redundant Degrees of Freedom

Control of arm movements when the number of joints exceeds the degrees of freedom necessary for the task requires a strategy for selecting specific arm configurations out of an infinite number of possibilities. This report reviews strategies used by human subjects to control the shoulder, elbow, and wrist (three degrees of freedom) while moving a pointer to positions in a horizontal plane (two degrees of freedom). Analysis of final arm configurations assumed when the pointer was at the target showed the following: (a) Final arm configurations were virtually independent of the configuration at the start of the pointing movement, (b) subjects avoided configurations subjectively felt to be uncomfortable (e.g., those with extreme flexion or extension of the wrist), and (c) the results could be simulated by assigning hypothetical cost functions to each joint and selecting the arm configuration that minimized the sum of the costs. The fitted cost functions qualitatively agreed with psychophysically determined comfort; they appeared to depend on joint angle and on muscular effort. Simple neural networks can learn implicit representations of these cost functions and use them to specify final arm configurations. The minimum cost principle can be extended to movements that use the fingers as a fourth movable segment. For this condition, however, experiments showed that final configurations of the arm depended upon initial configurations. Analysis of movement trajectories for arms with three degrees of freedom led to a control model in which the minimum cost principle is augmented by a mechanism that distributes required joint movements economically among the three joints and a mechanism that implements a degree of mass-spring control.

Affect and age: cross-sectional comparisons of Structure and prevalence

The self-reports of 207 young-adult (ages 18-30), 231 middle-aged (ages 31-59), and 828 older-adult (age 60 and over) Ss were used to study the structure of affect. Affects were represented by terms included in various circumplex arrays of emotions as presented by previous investigators. A set of 46 affects was subjected to exploratory analysis, and a final set of 38 affects was subjected to confirmatory factor analysis. The goodness of fit of each group's factor loadings to the hypothesized factors of positive affect, depression, anxiety-guilt, contentment, hostility, and shyness was not up to the desired .90 level, and some significant differences in factor structure were observed for each age-group comparison. There were few age differences in levels of positive affect. Depression was most frequent among younger Ss and least frequent among older Ss. Younger Ss were most often anxious and shy. Older Ss were most often content and least often hostile.

ZAP-1 DNA binding activity is first detected at the onset of zona pellucida gene expression in embryonic mouse oocytes

ZAP-1 (zona pellucida gene activating protein-1) is a putative transcription factor controlling the oocyte-specific expression of mouse and human zona pellucida genes. The DNA binding activity of ZAP-1 first appears in oocytes from 19-day-old mouse embryos and reaches a maximum level at 10 days after birth. This developmental profile closely parallels that of mouse zona pellucida gene transcription, which is detected in oocytes at 19 days of fetal life using a sensitive RT-PCR method and is maximal in 10-day-old animals. DNA binding activity similar to that of ZAP-1 is present in ovarian extracts from rat, human, and opossum, suggesting that the ZAP-1 protein may be conserved among mammals.