Normal Eggs Research Articles

Anucleate Caenorhabditis elegans sperm can crawl, fertilize oocytes and direct anterior-posterior polarization of the 1-cell embryo.

It has long been appreciated that spermiogenesis, the cellular transformation of sessile spermatids into motile spermatozoa, occurs in the absence of new DNA transcription. However, few studies have addressed whether the physical presence of a sperm nucleus is required either during spermiogenesis or for subsequent sperm functions during egg activation and early zygotic development. To determine the role of the sperm nucleus in these processes, we analyzed two C. elegans mutants whose spermatids lack DNA. Here we show that these anucleate sperm not only differentiate into mature functional spermatozoa, but they also crawl toward and fertilize oocytes. Furthermore, we show that these anucleate sperm induce both normal egg activation and anterior-posterior polarity in the 1-cell C. elegans embryo. The latter finding demonstrates for the first time that although the anterior-posterior embryonic axis in C. elegans is specified by sperm, the sperm pronucleus itself is not required. Also unaffected is the completion of oocyte meiosis, formation of an impermeable eggshell, migration of the oocyte pronucleus, and the separation and expansion of the sperm-contributed centrosomes. Our investigation of these mutants confirms that, in C. elegans, neither the sperm chromatin mass nor a sperm pronucleus is required for spermiogenesis, proper egg activation, or the induction of anterior-posterior polarity.

Distribution of acid sphingomyelinase in human various body fluids.

Enzyme activities of acid sphingomyelinase (ASM) were determined in various human cell-free body fluids, serum, cerebrospinal fluid, urine, salivary fluid, tear fluid, and synovial fluid, using assay buffers with or without Zn2+ -cation. Although ASM activity was not detected in the cerebrospinal fluid, the other fluids demonstrated significant enzyme activities of ASM. All ASMs detected in the fluids were stimulated by the addition of Zn2+ -cation, suggesting that those enzymes are secretory ASM derived from ASM gene. We suggest a possible enzymatic diagnosis of Niemann-Pick disease types A and B using those body fluids. Interestingly, salivary and tear fluids showed much higher activities of ASM than those of the other fluids. Because sphingolipids, especially sphingomyelin, are major constituents of a normal diet, especially, milk, eggs, and meat products, we suggest that ASM in the salivary gland may play an important role in the digestion of sphingomyelin in a normal diet.

DETECTION OF SURFACE CRACKS IN SHELL EGGS BY ACOUSTIC IMPULSE METHOD

A nondestructive quality inspection technique using acoustic impulse response method was developed for thedetection of surface cracks in an eggshell. An experimental system was built to generate the impact force, measure theresponse signal, analyze the frequency spectrum, and classify the eggs as cracked or normal. This system includes animpulse generating unit, an egg holding seat, a microphone with a preamplifier, and a DSP board installed in a personalcomputer. A multivariate discriminant analysis and a multiple regression analysis were used to develop classificationcriteria for the detection of surface cracks in the eggshell. The error rates in estimating cracked eggs as normal (type Ierror) and estimating normal eggs as cracked (type II error) were found to be 6% and 4%, respectively. The measuredprocessing time for classification was 200 ms/egg with the online inspection algorithm.

Requirement for Wnt3 in vertebrate axis formation.

Several studies have implicated Wnt signalling in primary axis formation during vertebrate embryogenesis, yet no Wnt protein has been shown to be essential for this process. In the mouse, primitive streak formation is the first overt morphological sign of the anterior-posterior axis. Here we show that Wnt3 is expressed before gastrulation in the proximal epiblast of the egg cylinder, then is restricted to the posterior proximal epiblast and its associated visceral endoderm and subsequently to the primitive streak and mesoderm. Wnt3-/- mice develop a normal egg cylinder but do not form a primitive streak, mesoderm or node. The epiblast continues to proliferate in an undifferentiated state that lacks anterior-posterior neural patterning, but anterior visceral endoderm markers are expressed and correctly positioned. Our results suggest that regional patterning of the visceral endoderm is independent of primitive streak formation, but the subsequent establishment of anterior-posterior neural pattern in the ectoderm is dependent on derivatives of the primitive streak. These studies provide genetic proof for the requirement of Wnt3 in primary axis formation in the mouse.

Dietary L-Threonine Responses in Laying Hens

Genetic improvements in laying hens have increased egg productivity without increasing feed intake. Greater hen productivity may warrant increased amino acid needs. However, amino acid needs of commercial layers, beyond methionine and lysine, are poorly understood.This study was conducted to evaluate threonine responses on egg production traits in ISA-Babcock hens after peak production. Treatments consisted of five levels of digestible threonine (0.43, 0.47, 0.49, 0.52, and 0.57% of diet) administered at 62-72 or 70-80 wk of age. The lowest level of digestible threonine (0.43% of diet) represents 100% of the 1994 NRC recommendations and a threonine:lysine ratio of 0.62. Egg production, egg weight, feed intake, and feed conversion were measured during both time periods.Egg production (P<.011), egg weight (P<.012), and feed conversion (P<.004) improved as threonine was increased above the 1994 NRC suggested threonine recommendation. Increasing dietary threonine increased threonine intake (P<.001). A threonine:lysine ratio of 0.68 appears adequate for normal egg production traits of post-peak hens.

A fluorescence dequenching method for monitoring exocytotic membrane fusion in fertilization of single sea urchin eggs

A method for monitoring exocytotic membrane fusion by using a fluorescent membrane probe is presented. The method is based on the relief from concentration‐dependent self‐quenching (dequenching) of fluorescence of 5‐N‐(octadecanoyl)aminofluorescein (AF18), an amphiphilic derivative of fluorescein. The validity and usefulness of this method were shown by the following results: 1) self‐quenching of AF18 fluorescence occurred in the plasma membrane of unfertilized eggs of a sea urchin, Pseudocentrotus depressus, which were heavily stained with the fluorescent dye; 2) dequenching of AF18 fluorescence occurred upon fertilization in normal eggs but not in EGTA‐injected eggs; 3) Ca2+ induced both AF18 fluorescence dequenching and cortical granule disappearance in the isolated sea urchin egg cortex; and 4) simultaneous measurements of the intracellular Ca2+ concentration ([Ca2+]i) and dequenching of AF18 fluorescence by using a simple one‐excitation and two‐emission wavelength system.

A fluorescence dequenching method for monitoring exocytotic membrane fusion in fertilization of single sea urchin eggs

A method for monitoring exocytotic membrane fusion by using a fluorescent membrane probe is presented. The method is based on the relief from concentration-dependent self-quenching (dequenching) of fluorescence of 5-N-(octadecanoyl)aminofluorescein (AF18), an amphiphilic derivative of fluorescein. The validity and usefulness of this method were shown by the following results: 1) self-quenching of AF18 fluorescence occurred in the plasma membrane of unfertilized eggs of a sea urchin, Pseudocentrotus depressus, which were heavily stained with the fluorescent dye; 2) dequenching of AF18 fluorescence occurred upon fertilization in normal eggs but not in EGTA-injected eggs; 3) Ca 2+ induced both AF18 fluorescence dequenching and cortical granule disappearance in the isolated sea urchin egg cortex; and 4) simultaneous measurements of the intracellular Ca 2+ concentration ([Ca 2+] i) and dequenching of AF18 fluorescence by using a simple one-excitation and two-emission wavelength system.

Characterisation of `swollen yolk-sac syndrome' in the Australian freshwater fish Murray cod, Maccullochella peelii peelii, and associated nutritional implications for large scale aquaculture

The Murray cod is artificially propagated by harvesting naturally spawned fertilised eggs laid in nest boxes by captive, pond-reared broodfish, in mid to late southern spring and early summer. From 1988–1993, a condition referred to as `swollen yolk-sac syndrome' (SYSS) accounted for increasingly significant mortalities of Murray cod eggs and newly hatched larvae, often resulting in total mortality of eggs and larvae during incubation and larval rearing stages. SYSS appears to be similar to the well known `blue-sac disease' (BSD) in salmonids but without the `bluish tinge' coloration of the serous fluid in the yolk-sac attributed to BSD. Early investigations ruled out that SYSS condition was caused by a pathogen, viral, bacterial or a parasitic protozoan, and this led to the subsequent investigations on the possible nutritionally related causes of the syndrome, which are reported here. The eggs of normal and SYSS spawns differed in many respects; the latter were lighter and had less moisture ( P<0.05), but did not differ in the amount of protein and/or lipid content per egg. The free amino acid (FAA) content of the two types of eggs were different however, when all the essential amino acids (EAA) and non-essential amino acids (NEAA) of the FAA pool were found in significantly lower amounts (nmol/egg) in SYSS eggs (EAA—11.84±0.0.90; NEAA—10.68±0.66) compared to normal eggs (EAA—21.67±1.04; NEAA—16.64±1.26). On the other hand, the differences in the total amino acid (TAA=protein bound+free) content and the fatty acid content of the egg types were relatively minor. It was also observed that broodstock, the spawns of which manifested SYSS, when allowed to forage in a relatively large pond, with ample natural food sources, for a period of time, their subsequent spawns tended to be normal. In eggs and larvae of spawns of such rehabilitated females, the amount of individual amino acids of the FAA pool was intermediate to that of normal and SYSS. All evidence appears to indicate that the SYSS syndrome in Murray cod is related to broodstock nutrition, possibly a result of cumulative effects of dietary deficiencies over time.

Development of maternal IgG-free chick obtained from surgically bursectomized hen

IgG-free eggs and chicks were developed, so as to study the role of maternal IgG in the development of the immune system. Surgical bursectomy on the 18th day of incubation deprived chickens of B cells and eliminated IgG synthesis. Bursectomized chickens are usually dead before sexual maturity under conventional conditions. When surgically bursectomized chickens were housed in an isolated clean room and antibiotics were administered to them, they could survive to sexual maturity. Finally, we succeeded in obtaining IgG-free fertilized eggs and maternal IgG-free chicks from surgically bursectomized hens. The amount of yolk IgG in IgG-free eggs was one-ten thousandth less than that in normal eggs. The level of IgM in the serum of maternal IgG-free chicks reached six times higher than that of normal chicks 5 days after hatching.

Underwater nesting by the Australian freshwater turtle Chelodina rugosa: effect of prolonged immersion and eggshell thicknesson incubation period, egg survivorship, and hatchling size

The northern long-necked turtle, Chelodina rugosa, occupies seasonally ephemeral freshwater wetlands in thewet–dry tropics of northern Australia. The species has a highly unusual nesting strategy in that nesting takes place under waterwhen wetland habitats are flooded. Embryonic development proceeds when floodwaters recede during the annual dry seasonand hatchling emergence coincides with the start of the following wet season. This study examined the influence of duration ofimmersion of eggs on hatchling size and hatching success under laboratory conditions. Prolonged immersion of eggs in waterresults in smaller hatchlings and shorter incubation times, but does not increase egg mortality during incubation. Leaching ofcalcium from the eggshell, resulting in reduced availability of calcium to the developing embryo, may explain the smallerhatchlings and shorter incubation period. Hatchlings from thin-shelled eggs, in which shell formation was incomplete, weresmaller and hatched sooner, indicating that the eggshell plays a role in determining hatchling size and incubation period.Thin-shelled and normal eggs had equivalent egg survivorship, indicating that the eggshell is unimportant in egg survivalduring immersion.

Comparative development of the ovary and production, fertility and hatchability of eggs from traditional turkeys and a contemporary male-line fed ad libitum or restricted

1. Ovarian function was assessed at first egg and at 44 and 54 weeks of age in traditional turkeys and in a male-line fed ad libitum or restricted to 0.5 of ad libitum during rearing. Egg production was recorded daily and fertility and hatchability were determined at 2 ages. 2. Age at sexual maturity did not differ between the 3 treatments. 3. The number of follicles at first egg in the male line averaged 16.3 compared with 8.9 in traditional turkeys. Food restriction in the male line decreased the number of yellow follicles to 14.6 at first egg and restricted birds were largely in a non-reproductive state from 44 to 54 weeks of age. 4. The total number of recorded ovipositions to 54 weeks of age in male line fed ad libitum or restricted and traditional turkeys respectively were 40.1, 25.2 and 70.7; comparable productions of normal shelled eggs were 28, 20 and 66.3. 5. There were no differences between treatments in fertility after a single insemination at 2 different ages. Hatch of fertiles after the first inseminations were 71.4, 45.5 and 90.3 respectively for male line fed ad libitum or restricted and traditional turkeys.

Intralesional steroids augment the effect of endoscopic dilation in corrosive-induced esophageal strictures

functional dyspepsia (5 men and 15 women, ages 20 to 55 years) with dysmotility-like dyspepsia symptoms (Rome criteria). Subjects consumed a light breakfast (4 oz. of apple juice and toast with butter or margarine) 2-3 hours before the EGG test. In the laboratory, subjects ingested water until feeling full (water load test). EGGs were recorded for 15 min. preand 30 min. post-water ingestion. The percentages of EGG total power in the bradygastria (0-2.25 cycles per min., cpm), normal (2.25-3.75 cpm), tachygastria 3.75-10 cpm) and duodenal (10.0-15 cpm) ranges were calculated. Data from control subjects were used to establish normative EGG data (mean +_ 1 SD). EGG results from each of the 20 patients were compared with the normative EGG data to determine whether a given patient's EGG fell within (normal result) or outside (abnormal result) the normal range. Results: Abnormal EGG responses to the water load test were found in 11 of 20 patients (55%). The Normal-EGG and Abnormal-EGG patient groups drank similar volumes of water (Abnormal-EGG = 395 +-41 ml, Normal-EGG = 385+-41 mi). The Abnormal-EGG group showed an increase in bradygastria and decrease in 3 cpm activity in response to the water load that was not observed the Normal-EGG group (F[3/54]=4.6, p <0.05 and F[3/54]=3.6, p < 0.05, respectively). In addition, the Abnormal-EGG group showed more tachygastria throughout the recording period compared to the Normal-EGG group (F[1/18]=5.8, p < 0.05). Conclusions: 1) In controls and patients the water load test provides a standard stimulus for evaluating gastric myoelectrical activity responses with the EGG; 2) Patients with dysmotilitylike dyspepsia may be defined in terms of normal vs. abnormal EGG responses, responses that provide an objective measure for definitions of functional dyspepsia and treatment protocols.

Chamber Volume Requirements for Reproduction of the ZebrafishDanio rerio

Abstract The zebrafish or zebra danio Danio (=Brachydanio) rerio has recently become a major vertebrate model for the study of developmental biology, neurobiology, and molecular genetics. As a result, most research universities have now invested considerable resources in the construction of large zebrafish facilities. A key element in the design of these facilities is maximizing the efficiency of available space. Here we report on the effects of aquarium chamber volume on the reproduction of zebrafish, with the objective of identifying the minimal volume required for normal egg production. Six adults (two males and four females) were tested in chamber volumes of 500, 400, 300, 200, and 100 mL. Results were compared with those from a control volume of 3.5 L. Eggs were removed from the test chambers after spawning and incubated in petri dishes at 28°C. Total egg production, percent of eggs hatching, and larval length at 96 h postfertilization were used to evaluate breeding success. Compared with the control, egg production was not significantly affected by reduced aquaria volumes of 500, 400, and 300 mL. However, mean egg production from a test volume of 200 mL was only 48% of the control egg production (P < 0.05), and at a test volume of 100 mL, egg production was reduced to 26% of the control value (P < 0.005). Percent egg hatch and 96-h larval length were not affected at any test volume.

Underwater nesting by the Australian freshwater turtle Chelodina rugosa: effect of prolonged immersion and eggshell thicknesson incubation period, egg survivorship, and hatchling size

The northern long-necked turtle, Chelodina rugosa, occupies seasonally ephemeral freshwater wetlands in thewet–dry tropics of northern Australia. The species has a highly unusual nesting strategy in that nesting takes place under waterwhen wetland habitats are flooded. Embryonic development proceeds when floodwaters recede during the annual dry seasonand hatchling emergence coincides with the start of the following wet season. This study examined the influence of duration ofimmersion of eggs on hatchling size and hatching success under laboratory conditions. Prolonged immersion of eggs in waterresults in smaller hatchlings and shorter incubation times, but does not increase egg mortality during incubation. Leaching ofcalcium from the eggshell, resulting in reduced availability of calcium to the developing embryo, may explain the smallerhatchlings and shorter incubation period. Hatchlings from thin-shelled eggs, in which shell formation was incomplete, weresmaller and hatched sooner, indicating that the eggshell plays a role in determining hatchling size and incubation period.Thin-shelled and normal eggs had equivalent egg survivorship, indicating that the eggshell is unimportant in egg survivalduring immersion.

Influence of yolk blackish pigmentation of Siberian sturgeon on reproductive performance and larval survival

Within a cohort of farmed Siberian sturgeon (Acipenser baeri), some females produce eggs which show a blackish pigmentation of the ooplasm. An experiment was carried out to test whether this characteristic might influence the reproductive success and larval survival as compared to females having usual non-pigmental yolk. There were no differences in either the progress of germinal vesicle migration or the 50% in vitro maturation time course before hormonal injection. The latency, relative quantity of eggs, fertilization rate and embryonic survival were similar. The pigmentation of yolk significantly depressed the second part of embryogenesis. Neither the number of hatchlings, normal or abnormal, survival after weaning and the mean weight of 14 days post-hatch larvae were different. For the first time, rates of hatching for normal (70%), abnormal (11%) and non-hatched (7%) larvae, referred to the embryo survival at final stages, are reported with normal appearance eggs. © Rapid Science Ltd. 1998

Injection of a porcine sperm factor induces activation of mouse eggs.

Injection of sperm preparations into mammalian oocytes and eggs has been shown to elicit persistent [Ca2+]i oscillations that closely resemble fertilization-associated Ca2+ release. However, the ability of these sperm fractions to initiate egg activation has not been clearly demonstrated. In the present experiments, mouse eggs injected with a porcine sperm preparation were evaluated for early and late events of activation. Events monitored included, among early events, the generation of [Ca2+]i oscillations and cortical granule exocytosis and, among late events, the decrease in histone H1 and myelin basic protein kinase activities, polar body extrusion, pronuclear formation, and cleavage to the two-cell stage. Injection of sperm fractions consistently evoked [Ca2+]i oscillations that, in turn, initiated all events of activation. Uninjected control eggs or eggs injected with buffer or heat-treated sperm fractions failed to show Ca2+ responses or activation. In addition, injection of sperm fractions into recently ovulated eggs (experiments were concluded within 15 hr after human chorionic gonadotropin administration) induced high rates of activation, while similarly aged eggs exposed to 7% ethanol for 5 min, a known parthenogenetic treatment, failed to activate. Together these results indicate that injection of sperm fractions elicits [Ca2+]i oscillations that are capable of initiating normal egg activation. These results support the hypothesis that a sperm component participates in the generation of fertilization-associated [Ca2+]i oscillations.

Effect of prey density on sex ratio of two predacious mites, Phytoseiulus persimilis and Amblyseius womersleyi (Acari: Phytoseiidae)

The sex ratios of two phytoseiid mites, Phytoseiulus persimilis and Amblyseius womersleyi, were observed under various prey conditions. Upon consumption of abundant prey, both phytoseiids produced progeny in a female-biased sex ratio (approximately 0.8 females). When few prey were consumed, the sex ratio was lowered to 0.5 (the unbiased sex ratio). Under the conditions in which the unbiased sex ratio was observed, male and female progeny appeared in an alternating sequence. To determine the change in the sex ratio and the sequence of progeny, the size of eggs deposited by females under various prey conditions was first compared. Survivorship and developmental rate of progeny (immatures) hatched under ample and poor prey conditions were also examined. The eggs deposited under poor prey conditions were smaller than those deposited under ample prey conditions. This is an indication that the phytoseiid females did not invest extra energy into the eggs to secure survival of their progeny under poor prey conditions. The male and female progeny from the small eggs developed slowly, probably due to the small egg size. However, hatchability of the small eggs and survival of the immatures were the same as those of the normal eggs when the immatures were reared under ample prey conditions. The immature survivorship was little affected by the prey consumption rate of their mothers when the immatures were reared under poor prey conditions. We concluded that the sex ratio of phytoseiid mites is not determined by the characteristics of the progeny, but by the nutritious condition of the females.

Fossil egg sacs of Diaptomus (Crustaceae: Copepoda) in Late Quaternary lake sediments

In contrast to the exoskeleton or normal egg sacs of copepods, egg sacs with resting eggs of Diaptomus castor are exceptionally robust and can be preserved in the Quaternary sedimentary record. Egg sacs referred to Diaptomus cf. castor have been recovered from Late- and Postglacial lake sediments in Denmark and Greenland. The identification of fossil copepod egg sacs is important, since Copepoda is a very important group of invertebrate animals in freshwater bodies; but a group that is rarely reported from lake sediments.

Reproduction in the Suwannee cooter, Pseudemys concinna suwanniensis

The Suwannee cooter, Pseudemys concinna suwanniensis, is the largest emydid turtle in North America. From 1988 to 1993, we studied the reproductive and nesting biology of a population of this turtle in the headwaters of the Wakulla River in northern Florida. Based on 239 marked females, we estimated a population of about 305 adult females in ca 5 km (41 ha) of river. Nesting females ranged in plastron length (PL) from 304 to 383 mm and in body mass from 4.5 to10.5 kg. We estimate that female body size at maturity varies by as much as 50 mm, with a mean size at maturity of ca 330 mm PL, or only about 1 cm less than the mean PL. The negligible post-maturational growth of adult females, coupled with their size range, suggests that sexual maturity is less a function of size than of age, which we estimate minimally at 10 years. Nesting begins in late March or early April and extends into early August. Females may lay as many as five or more clutches at intervals of approximately 16-25 days. Most, if not all, mature females nest annually. Nesting is diurnal and frequently coincides with rainfall. Typical clutches contain 8-27 eggs (mean 17.5). Average annual reproductive potential may approach 70 eggs, with a maximum for individuals of &gt;100. Normal egg and hatchling sizes span ranges of 9.8-21.7 g and 6.8-14.6 g, respectively, and are, at most, only weakly correlated with female body size. Clutch mass tends to increase with body size, but relative clutch mass, which averages ca 0.05. does not. These results suggest this species is an egg number maximizer rather than an egg size optimizer. We estimate for the population an annual production of ca 26,700 eggs equivalent to 10.6 kg/ha/yr. Hatchlings may emerge from nests in the fall or may overwinter underground and delay emergence until the following spring. Sex determination of hatchlings is temperature-dependent, with a pivotal temperature at constant incubation temperatures of ca 28.4°C. Although this population occurs in a state park, the concentration of nesting activity principally along a linear corridor of artificial habitat has fostered nest predation approaching 100 percent; chief egg predators are raccoons (Procyon lotor) and fish crews (Corvus ossifragus). Some nesting females are also depredated, principally by raccoons. Continuing forest growth threatens to shade out the main nesting site and to skew the sex ratios of hatchlings toward males. We present management recommendations both for this population and for the species throughout Florida.

Phenoloxidase Activity in the Reproductive System of Biomphalaria glabrata: Role in Egg Production and Effect of Schistosome Infection

Infection by larval trematodes often causes a cessation of egg production in its molluscan intermediate host and is referred to as parasitic castration. Because phenoloxidase (PO) has been shown to be involved in egg formation in other invertebrate species, we investigated the role of PO in normal egg production in the snail, Biomphalaria glabrata, and the effects of Schistosoma mansoni infection on the PO pathway in this snail. Our data showed that PO activity in the albumen gland (AG) is initially expressed when snails reach a size of approximately 8 mm in shell diameter and continues to increase as snails grow, indicating a developmental link between snail size and AG PO expression. Egglaying was also shown to be coincidental with the onset of PO expression in the AG, thereby supporting a direct association between PO activity and egg production. In addition, exposure of snails to diethyldithiocarbamate (DDC), a PO inhibitor, affected normal in vivo egg production, as evidenced by a significant decrease in the numbers of eggs laid in DDC-treated groups compared to nontreated groups. Normal resumption of egg-laying activity in treated snails following withdrawal of the drug indicated that inhibition was reversible. Taken together, the results of our developmental and DDC-exposure studies provide strong support for a crucial role of PO in normal egg production in this animal. Finally, AG PO activities of infected and uninfected control snails were measured over the course of S. mansoni infection. Our results showed that both total and specific enzyme activities in the AG of infected snails were significantly decreased at 28 and 33 days postinfection (PI) when compared to those of control snails. Results of subsequent experiments assessing the effects of larval infection on L-tyrosine (PO substrate) levels in AG and ovotestis revealed a significant increase in the levels of this compound in both organs over the course of infection. It is concluded that AG PO activity is functionally linked to egg formation in normal snails and that a strong association exists between parasite-mediated decrease in AG PO activity and parasitic castration. However, from the data presented, a direct causal relationship linking infection, decreased PO, and castration has yet to be established.