Embryonic expression of juvenile hormone binding protein and its relationship to the toxic effects of juvenile hormone in Manduca sexta

The juvenile hormones (JHs) regulate a diverse array of insect developmental and reproductive processes. One molecular target of JH action is its transporter, hemolymph JH binding protein (hJHBP); in the larva of the tobacco hornworm, Manduca sexta, low doses of JH can immediately increase hJHBP gene expression. Less explored are the effects of JH on embryological development, where early hormonal treatment has been shown to affect embryonic development and pupation. This study examines the egg form of JHBP and its gene expression during embryogenesis of M. sexta, as well as the phenotypic effect JH treatment has on embryos and on JHBP gene expression. We here demonstrate that the preponderance of JHBP found in the egg is maternally derived and that the embryonic gene and protein appear identical to those found in the larva. Expression of the JHBP gene begins in both the embryo itself and extra-embryonic tissues 15 h after fertilization, long before emergence of a functional fat body and circulatory system. Topical application of low JH doses to early embryos resulted in larval abnormalities while high doses of the hormone induced embryonic mortality. These effects are not mediated through regulation of the JHBP gene, since embryonic expression appears invariant in response to JH challenge. The toxicity of JH is tightly correlated with the concentration of unbound hormone.     

Persistence of egg pocket architecture in redds of chum salmon, Oncorhynchus keta

Synopsis Analysis of frozen cores of gravel surrounding the egg pockets of chum salmon, Oncorhynchus keta, collected in the fall revealed that spawning activity by females purged about 75 % of the fine sediments from the stream bed. The egg pocket was one of four distinct vertical strata detected in the cores. There was an undisturbed layer below the egg pocket, and separate bridge and cover strata above the egg pocket, all defined by different particle size distributions. However, by spring most of the egg pockets had been infiltrated with fine sediment and the particle size distribution approached background levels. The most likely physical factors responsible for these results were: (1) intrusion of fine sediments through the cleaned surface gravel, (2) lateral subsurface migration of fine sediment into interstitial voids, (3) scour of the surface gravel and subsequent deposition of a sand rich bedload, and (4) superimposed spawning activity of other fish, causing disturbance of the cleaned surface gravel and exposing the egg pocket to intrusion of fine particles. We conclude that, while female salmon substantially affect the physical environment of their embryos, subsequent sediment transport processes and fine bedload flux tend to return this environment to pre-spawning conditions.     

Use of Carbopol resin for carp pituitary administration improves the fertilization percentage of northern pike (<Emphasis Type="Italic">Esox lucius</Emphasis> Linnaeus) eggs in commercial hatcheries

The efficiency of northern pike (Esox lucius Linnaeus) fry production via hormonal treatment of wintered broodstock is, in general, relatively low due to low egg fertilization percentage. It has been experimentally demonstrated that administration of acetone-dried carp pituitary extract in a slow-release vehicle of aqueous dispersion of Carbopol 971 P resin (CP) resulted in a higher mean fertilization percentage, possibly because the gradual hormone action could optimally control ovarian follicle maturation and ovulation. This new method of hormonal induction of ovulation was tested in a large-scale hatchery production of northern pike fry. In the present study, data on fertilization percentage collected between 2002 and 2006 at two prominent hatcheries in Hungary were analyzed. Administration of acetone-dried carp pituitary in a 2.5% CP vehicle resulted in higher fertilization (76.4 ± 7.7%; mean ± SD) compared to the saline vehicle group (59.3 ± 10.8%). The vehicle used did not affect the ovulation ratio. According to these results from large-scale production, the new method could be suitable to have wide application for induced breeding of northern pike. Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species     

Morphological characterisation of wheat (T. aestivum L.) egg cell protoplasts isolated from immature and overaged caryopses

 The morphological features and fine structure of wheat egg cell protoplasts isolated from premature (3 days prior to anthesis) and overaged (12 days after anthesis) caryopses were compared. Except for shape, the young egg cell protoplast showed the same morphological characteristics as the egg cell in planta at the time of anthesis. Young and adult egg cell protoplasts were spherical in shape. Polarity could not be identified exactly with the methods used. During aging, the egg cell increased considerably in volume. The adult egg showed the typical features (membrane blebbing, autophagous vacuoles) of programmed cell death. It appears that after a long life-span (about18 days) cells of the female gametophyte undergo apoptosis. Received: 19 August 1998 / Revision accepted 2 November 1998     

Reproductive strategy of the snapping shrimp Alpheus armillatus H. Milne-Edwards, 1837 in the South Atlantic: fecundity,egg features,and reproductive output

Summary

The family Alpheidae, composed by shrimps of relatively small size, popularly known as snapping shrimps, is the one of the most diverse decapod groups. These shrimps are found worldwide and occur in tropical and subtropical waters, from the intertidal zone to great depths. We investigated reproductive aspects of Alpheus armillatus, in order to gather information on egg production, aiming to enhance knowledge of its reproductive strategies in a population in an intertidal area of the South Atlantic. Ovigerous females were collected under rocks, in May and July 2006 (dry season) and in November 2006 and March 2007 (rainy season). Egg production and reproductive output were analyzed and compared seasonally and during the period of embryonic development. Females measured on average 11.28 mm CL, with a mean of 763 eggs and 0.10 mm3 egg volume. The egg volume of this population was smaller than previous estimates for other species of snapping shrimps, but the mean egg number was higher. The volume of eggs doubled during the incubation period, but despite this increase, no significant loss of eggs was observed. Alpheus armillatus invests on average about 12% of body weight in reproduction. The proportional investment in egg production is significantly higher in the rainy season when compared with the dry season (17.9% vs 4.8%), correlated with higher temperatures and increased food availability at this time. Our results corroborated the hypothesis of a pattern of egg production influenced by environmental conditions and intraspecific variability among the family Alpheidae, as a function of the biogeographic region.     

Effects of riboflavin supplementation level on health,performance, and fertility of organic broiler parent stock and their chicks

Data from breeder hens and chicks are particularly critical for the development of vitamin B2 recommendations for organic poultry. To test safe thresholds of supplementation, 100 breeder hens (Hubbard JA 57 K) and ten cockerels were allocated to ten housing groups, with each receiving supplementation of either 4.0 (treatment CON) or 2.5 mg (treatment RED) riboflavin per kg feed. After 15 weeks of experimental feeding, 256 eggs were incubated. From the hatched chicks (Hubbard S757), 192 were allocated to four treatments based on their parents’ treatment (CON- or RED-) and on their own supplementation of either 4.0 (-CON) or 2.5 mg (-RED) riboflavin per kg feed. Two groups of each combination (CON-CON, CON-RED, RED-CON, RED-RED), each with 24 chicks of both sexes, were fattened for nine weeks and slaughtered. Analysis of total riboflavin (sum of native concentrations and supplements) in the parent’s feeds revealed an average, over the 15 weeks, of 7.8 and 5.8 mg per kg feed for CON and RED, respectively. Body weight, plumage integrity, gait appearance, footpad, claw and keel bone integrity, lesion scores, laying performance, and egg mass were found to be of similarly high levels for all hens without any treatment effects. Performance traits of the hens in both treatments reached the specifications of the producer for this genotype. Yolk and albumen riboflavin concentrations were not affected although yolk colour in the RED treatment group became darker. Fertility was not affected, and hatchability was 100 per cent. Total riboflavin concentrations in the broiler diets were on average, over 9 weeks, 8.2 and 6.1 mg/kg for CON and RED, respectively. In chicks, RED treatment of their parents led to significant depressions of feed intake and growth. The RED treatment of the chicks themselves also impaired growth. Growth rates of the CON-CON treatment were in line with the specifications of the producer for this genotype. Plumage scores, footpad integrity and walking appearance of the broilers, and dressing percentage of the carcasses were not affected by treatment. The RED treatment of chicks caused lower spleen and heart weights, while pancreas and liver weights, and liver riboflavin concentrations were not affected. In conclusion, supplementation of 4.0 mg/kg to organic diets did not evoke any health or performance problems for breeder hens or broiler chicks, while a supplementation level of 2.5 mg per kg feed led to reduced weight gains, although without any other riboflavin deficiency symptoms.     

The effects of egg position, egg mass size, substrate and biofouling on embryo mortality in the squid Sepioteuthis australis

Using a combination of laboratory and field investigations, this study examined embryo mortality in the southern calamary Sepioteuthis australis as a function of egg mass size, the substrate upon which the mass is attached, the position of the embryo within the mass, and the degree of biofouling. Egg mass size ranged from 2 to 1,241 egg strands, however most masses consisted of 200–299 strands. Small egg masses (<300 strands) were generally attached to soft-sediment vegetation (Amphibolis antarctica, Heterozostera tasmanica, Caulerpa sp.), whereas larger masses (>300 strands) were either securely attached to robust macroalgae holdfasts (Ecklonia sp., Marcocystis pyrifera, Sargassum sp.) or unattached. Rates of embryo mortality were highly variable ranging from 2 to 25%. Both laboratory and field results indicated a positive relationship between egg mass size and embryo mortality. Larger, unattached egg masses contained twice as many dead embryos than those securely attached to a substrate. Mortality rates were significantly affected by the embryos’ relative position within the mass and were highest in embryos located near the attachment point of the egg strand, within the interior of the mass, and in close contact with the substrate. This was attributed to the inability of the embryos to respire adequately and eliminate metabolic wastes. Biofouling did not strongly influence embryo mortality, but colonisation occurred in areas conducive to growth, photosynthesis, and respiration indicating ‘healthy’ regions within the mass.     

Population responses and fatty acid profiles of Brachionus calyciflorus (Rotifera) in relation to different thermal regimes

Diurnal temperature fluctuations affect ectothermic species more than endothermic taxa. We tested the effect of three fixed temperatures (20, 25 and 30 °C) and a 24 h variable (20–30 °C) on the population growth and fatty acid profiles of the common rotifer Brachionus calyciflorus. Depending on the temperature treatment, the peak population abundances of B. calyciflorus varied from 65 to 80 ind./ml, the lowest being on variable temperature range. The rate of population increase varied from 0.31 to 0.52 per day, highest being at 30 °C. There was a curvilinear relationship between the population density and the egg ratio (number of eggs/female) in all the tested temperature regimes. The egg ratio was higher (>0.6) for treatments involving fixed temperatures, but for variable temperature regime, the egg ratios were lower (<0.5). Temperature also induced changes in the fatty acid content of B. calyciflorus. While the total saturated fatty acids increased, both mono-unsaturated and poly-unsaturated fatty acids decreased with increasing temperature regime. These results have been interpreted in relation to the role of temperature (both intensity and mode of exposure) on the population growth characteristics of rotifers.     

Uncoupling of growth and cytological development in egg follicles ofHeteropeza pygmaea (Dipt., Cecidomyiidae)

Summary Oogenesis of egg follicles in paedogenetic reproduction of the gall midgeHeteropeza pygmaea is accompanied by a relatively slight growth of the oocyte. Egg growth takes place mainly during embryonic development. The nurse chamber in the egg follicle degenerates only at the beginning of embryogenesis. When ovaries of the female larvae are cultured in vitro under male-determining conditions, the ovaries produce mostly male-determined egg follicles. These follicles show nurse chamber degeneration and they grow to about the size of an egg in late cleavage division or blastoderm stage developing in situ, but cytological development invariably stops at the first or second meiotic division. Thus, growth and cytological development in such follicles are uncoupled. The presence of a meiotic block in paedogenetically developing follicles ofH. pygmaea gives a clue to the mode of evolution of paedogenetic reproduction.Dedicated to Professor Dr. Hans Bauer on the occasion of his 75th birthday     

低剂量CO2激光对青椒,茄子生物学刺激效应的研究

本试验用８２５ｍｗ／ｃｍ￣２的ＣＯ＿２激光照射青椒种子１秒、３秒、５秒；茄子种子１０秒、１３秒、１５秒，以研究其生物学刺激效应，结果表明：１．激光照射提高了种子活力，２．激光照射增强了幼苗素质，并有显著促进早熟，增产的效果。