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1.
We examined Ixodes ricinus embryos between 18 and 28 days of development with light, scanning and transmission electron microscopy. The differences in inner structure attested to establish three successive developmental stages: days 18-20, day 23, and days 26-28. Between 18 and 20 days the embryos are at early stages of organogenesis. Salivary glands cannot be identified at that stage. In 23-day-old embryos salivary glands are already outlined but the structure of alveoles is still different from that in larvae in which the embryonic development has been completed. Gland cells start to form alveoles and become active between 26 and 28 days of the development. 相似文献
2.
Synopsis The ability of embryos of the viviparous scorpaenidSebastes melanops to take up nutrients from an exogenous substrate was demonstrated by incubating embryos at various stages of development
(18–30 days after fertilization) in14C-labeled glycine for 24 h. Uptake was highest for embryos at the latest stages (28–30 days) and increased at a linear rate
during the incubation period. Nutrient uptake was not time dependent in embryos at the early stages (18–22 days). Nutrient
utilization byS. melanops embryos was measured by the oxidation of14C-labeled glycine to14CO2. The amount of respired14CO2 by the oldest embryos increased significantly at a linear rate over the 24 h incubation period. There was no evidence of
nutrient utilization by the youngest embryos. The developmental changes we observed in the uptake and utilization of exogenous
glycine are supported by our previous findings that the oldest embryos have fully developed mouths and guts, and require additional
nutrition from intraovarian sources at this stage of development. 相似文献
3.
Summary Cell lines were isolated from three stages of embryos ofBlattella germanica dissociated with trypsin. The lines have been subcultured 50 to 134 times in 3 years. Line UM-BGE-1 was isolated from germ
band embryos at stages of segmentation and limb-bud formation (5 days old). Line UM-BGE-2 was derived from embryos at dorsal
closure (7 days old). Line UM-BGE-4 arose from embryos in the germ band and dorsal closure stages (5 and 7 days old); these
cells colonize as hollow spheres or vesicles. Line UM-BGE-5, isolated during organogenesis (10 days old), developed into two
distinct sublines. Subline α is composed of round cells that do not attach to the flask. Subline β grows as an attached monolayer;
the cells can be removed with a saline solution containing 20mM disodium dihydrogen Versenate?. Most of the cells of these lines have the diploid chromosome number (23 or 24) excepting line UM-BGE-1 in which the tetraploid
number predominates.
Presented in part at the 26th Annual Meeting of the Tissue Culture Association, at Montreal, Canada, 2–5 June 1975.
This investigation was supported by U.S. Public Health Service Research Grant No. AI 09914 from the National Institute of
Allergy and Infectious Diseases. This is Paper No. 9416, Scientific Journal Series, Minnesota Agricultural Experiment Station. 相似文献
4.
Frank P. Conte Kazunori Takano Akihiro Takemura George W. Boehlert 《Environmental Biology of Fishes》1991,30(1-2):127-134
Synopsis The purpose of the present investigation was to determine at what stages of embryonic development the sodium pump (Na+,K+-activated
ATP phosphohydrolase, EC 3.6.1.3) appears and whether the ontogeny of the sodium pump plays a role in the matrotrophic viviparity
ofSebastes. Early larval stages (stages 1–14) had embryonic tissues nearly devoid of Na, K-ATPase activity. After epiboly, tissues from
embryos taken from both species,S. schlegeli andS. taczanowskii, had significant levels of enzymatic activity coincident with the appearance of neuronal tissue in the head fold (stages
15–20). Maximal levels of specific activities of the enzyme were reached with the onset of the vascular circulation and the
opening of the buccal cavity together with maturation of the midgut and hindgut regions of the intestinal tract (stages 26
and 28). Ouabain, a specific inhibitor of Na, K-ATPase, was used to measure survival of embryos placed in different seawater
concentrations under in vitro conditions. The most sensitive stages to external ouabain were 26–30. These findings support
the hypothesis that the intestinal tract is functional prior to gestation and could be transporting important nutritive material
found in maternal ovarian fluid. 相似文献
5.
Embryonic, larval and juvenile development of the roughskin sculpin,Trachidermus fasciatus (Scorpaeniformes: Cottidae) 总被引:1,自引:1,他引:0
Naohiko Takeshita Norio Onikura Seiichi Matsui Seirô Kimura 《Ichthyological Research》1997,44(2-3):257-266
Embryonic, larval and juvenile development of the catadromous roughskin sculpin,Trachidermus fasciatus, were described using eggs spawned in an aquarium. The eggs, measuring 1.98–2.21 mm in diameter, were light reddish-yellow
and had many oil globules, 0.05–0.18 mm in diameter. Hatching occurred 30 days after spawning at 2.3–11.3°C. The newly-hatched
larvae, measuring 6.9–7.3 mm BL, had a single oil globule, 9–10+25–26=34–36 myomeres and 6 or 7 large stellate melanophores
dorsally along the gut. The yolk was almost resorbed, number of pectoral-fin rays attained 16–17, and two parietal, one nuchal
and four preopercular spines were formed, 5 days after hatching, at 8.2–8.4 mm BL. The oil globule disappeared, and one supracleithral
spine was formed, 11 days after hatching, at 8.9–9.5 mm BL. Notochord flexion began 15 days after hatching, at 9.7–10.3 mm
BL. A posttemporal spine was formed 20 days after hatching, at 10.7–10.9 mm BL. The first dorsal fin spines (VII–VIII), second
dorsal fin and anal fin rays (18–19, 16–18, respectively) appeared 23 days after hatching, at 12.0–13.7 mm BL. The pelvic
fin spine and rays (I, 4) were formed and black bands on the head and sides of the body began to develop 27 days after hatching,
at 13.8–15.8 mm BL.
Newly-hatched larvae swam just below the surface in the aquaria. Preflexion larvae (8.9–9.5 mm BL), in which the oil globule
had disappeared, swam in the middle layer, while juveniles (13.8–15.8 mm BL) began swimming on the bottom of the aquaria.
Swimming behavior observed in the aquaria suggested that the fish started to change to a demersal existence at the juvenile
stage. 相似文献
6.
S. D. Kashenko 《Russian Journal of Marine Biology》2009,35(5):422-430
The combined effects of temperatures of 14, 17, 20, 22, and 25°C and salinities of 36–12‰ on embryos and larvae of the sand
dollar Scaphechinus mirabilis was studied. Embryonic development is the most sensitive stage in the early ontogenesis of S. mirabilis. It is completed at a temperature of 14–20°C in a salinity range of 36–24‰ and at temperature of 22°C to 26‰. The fertilization
proceeds in wider ranges of temperature and salinity. Among the swimming larvae, blastulae showed the greatest resistance
to variations of these environmental factors. All the larvae survived at a temperature of 14–22°C and a salinity of 36–20‰,
and more than 70% of them at 18‰. The pluteus I is the most vulnerable stage; probably this is related to the formation of
the larval skeleton and transition to phytoplankton feeding. The survival of larvae at the age of 20 days was 100% at 14–22°
C and a salinity of 36–24‰, most of them survived at 14–20°C and a salinity 18‰. The temperature 25 ° C is the most damaging
for early development of S. mirabilis. The duration of development of that species lasts 28.5–29 days at 20°C and a salinity of 32.2–32.6‰. At 20 and 22°C, the
larvae settled and completed metamorphosis more quickly if sand from the parental habitat was present. The larvae did not
settle during the experiment (14 days) at 14 ° C and in the absence of sand. 相似文献
7.
Haoru Tang Zhenglong Ren Gari Krczal 《In vitro cellular & developmental biology. Plant》2000,36(1):47-50
Summary Well-developed somatic embryos were selected from a repetivively somatic embryo line derived from embryonic axes of immature
zygotic embryos of English walnut ‘No. 120’ (Juglans regia L.) for germination and conversion studies. In germinating dishes, somatic embryos germinated into only shoots, only roots,
or both shoots and roots. Without any pretreatment, 28% somatic embryos germinated, while those treated with 2.5–5.0 mg 1−1 (7.2–14.4 μmol) gibberellic acid (GA3) germinated at 25–28% and those receiving a cold treatment of 2–3 mo. at 3–4°C germinated at 30–43%. However, only 4–19%
of the germinating embryos showed both shoots and roots. Treated with desiccation, either with CaCl2·6H2O or Ca(NO3)2·4H2O at 20°C in the dark for 3 d, somatic embryos germinated at 85–91%, 57–69% of which had both shoots and roots. Treatment
with 2 mo. cold storage in combination with desiccation using Ca(NO3)2·4H2O resulted in 92% of somatic embryos germinating, 70% of which showed both shoots and roots. No significant differences were
observed between solid and liquid germination media. After transferring the germinating embryos to plantlet development media,
52–63% of those with both shoots and roots developed into plantlets while 11% with only shoots or 9% with only roots converted
into plantlets. Plantlet development was improved by using lower medium salts and sucrose concentrations. The addition of
activated charcoal enhanced root development, particularly root branching. Of 131 plants transplanted, 91 plants were acclimatized
to a greenhouse. 相似文献
8.
Optimization of <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation conditions in mature embryos of elite wheat 总被引:1,自引:0,他引:1
Immature embryos have been used frequently as target tissues in the genetical transformation of wheat. However, obtaining
a large number of high quality immature embryos throughout the year is a laborious and delicate process, because of the need
to cultivate the plants under controlled conditions. To circumvent this, we have employed mature embryos rather than immature
ones as starter explants for Agrobacterium-mediated transformation of an elite wheat (Triticum aestivum L.) cultivar EM12. The neomycin phosphotransferase ІІ (npt ІІ) and β-glucuronidase (gus) genes were used as selectable and screenable marker genes, respectively, to assess and optimize the performance of T-DNA
delivery. With the aid of an orthogonal design, the effect of four factors in combination on transfer DNA (T-DNA) delivery
was studied. These factors were preculture duration, different kinds of inoculation, length of inoculation and co-culture
condition. Optimal conditions for T-DNA delivery were obtained for mature embryos precultured for 14 days, followed by immersing
in inoculation suspension with full strength Murashige and Skoog (MS) salts in darkness at 23–25°C for 3 h, and then co-culturing
with Agrobacterium under desiccating condition in the dark at 23–24°C for 2–3 days. Complete analysis of transgene insertion demonstrated that
the optimized method for Agrobacterium-mediated transformation of mature embryos of wheat was efficient and practicable. 相似文献
9.
Germination responses ofMallotus japonicus (Thumb). Muell. Arg. seeds to temperature revealed a gap-detecting mechanism in the seed germination of the species. Among
various constant and alternating temperatures examined in the range from 12–40°C, only very limited temperature regimes were
found to be favourable for seed germination, specifically, alternating temperatures between 18–32°C and 28–40°C. A single
several-hour higher-temperature (32–40°C) treatment could also induce the germination of seeds which had been imbibed for
several days at a constant temperature in the range of 20–26°C, suggesting that there is a process requiring higher temperature
among the overal germination processes. Seeds located at or near the surface of denuded soil would have a good chance of experiencing
such a temperature change when several rainy days are followed by fine weather, while seeds beneath close vegetation would
not. On the other hand, the pressence or absence of light or a simulated ‘canopy ligh’ had little effect on the germination.
Therefore, it was concluded that the seeds ofM. japonicus have a ‘gapdetecting mechanism’ in the form of a higher-temperature requirement of a certain process involved in the overall
germination processes. 相似文献
10.
A new species of armored searobin, Paraheminodus longirostralis, is described from five specimens collected from New Caledonia at depths of 412–467 m. It is distinguishable from its three
known congeners in having 34 bony plates in the upper lateral row, a forward-directed spine on each plate between the 23rd–26th
and 31st–32nd plates in the upper lateral row, 6–7 + 1 + 20–21 = 27–28 gill rakers, an elongate body posterior to the anus
(49.9–52.1% standard length), an elongate rostral projection (53.0–59.3% head length), short upper jaw (42.1–43.4% head length),
an elongate pectoral fin (70.6–79.4% head length), and long preopercular spine (39.2–57.7% head length). 相似文献
11.
12.
Ravinder Kaur Grewal Monika Lulsdorf Janine Croser Sergio Ochatt Albert Vandenberg Thomas D. Warkentin 《Plant cell reports》2009,28(8):1289-1299
This is the first report on the production of double-haploid chickpea embryos and regenerated plants through anther culture
using Canadian cultivar CDC Xena (kabuli) and Australian cultivar Sonali (desi). Maximum anther induction rates were 69% for
Sonali and 63% for CDC Xena. Under optimal conditions, embryo formation occurred within 15–20 days of culture initiation with
2.3 embryos produced per anther for CDC Xena and 2.0 embryos per anther for Sonali. For anther induction, the following stress
treatments were used: (1) flower clusters were treated at 4°C for 4 days, (2) anthers were subjected to electric shock treatment
of three exponentially decaying pulses of 50–400 V with 25 μF capacitance and 25 Ω resistance, (3) anthers were centrifuged
at 168–1,509g for 2–15 min, and finally (4) anthers were cultured for 4 days in high-osmotic pressure (563 mmol) liquid medium. Anthers
were then transferred to a solid embryo development medium and, 15–20 days later, embryo development was observed concomitant
with a small amount of callus growth of 0.1–3 mm. Anther-derived embryos were regenerated on plant regeneration medium. Electroporation
treatment of anthers enhanced root formation, which is often a major hurdle in legume regeneration protocols. Cytological
studies using DAPI staining showed a wide range of ploidy levels from haploid to tetraploid in 10–30-day-old calli. Flow cytometric
analysis of calli, embryos and regenerated plants showed haploid profiles and/or spontaneous doubling of the chromosomes during
early regeneration stages. 相似文献
13.
Notonecta unifasciata Guerin eggs maintained at different stages of embryonic development in water at variable temperatures (2.2–25.6 °C) and for
periods of 4–12 weeks revealed maximum viability (>80 %) at the highest temperature. However, optimum nondevelopmental viability
was at 14.4 °C with eight-day-old embryos (>35 %). Short term (4 weeks) storage at 14.4 °C significantly increased egg viability.
Survival was poor (<20 %) at the 2 lowest temperatures. Eggs held at 14.4 °C for 12 weeks and sustainingca. 50 % mortality, may be a practical procedure for biological control.
相似文献
14.
K. S. Larsen 《Entomologia Experimentalis et Applicata》1995,76(3):241-245
A rearing method for the fleaCeratophyllus (Monopsyllus) sciurorum sciurorum, a pest on farmed mink in Europe, has been developed. The behaviour of egg-laying and the development period are described
at 23 °C and 80% r.h. The eggs ofC. sciurorum sciurorum hatched after 4–7 days and cocoons were formed 10–12 days later. The development period from egg to newly emerged adult was
23–32 days. Females emerged, in general, earlier than males. 相似文献
15.
At a time when global climate changes are forcing life to adapt to a warming and salinity-changing environment, it is essential to understand how future changes in ocean chemistry will affect species. This study evaluates the combined effects of temperature and salinity on survival and development of Upogebia pusilla larvae. Combinations were made from three temperatures (18, 23, and 28°C) and three salinities (15, 25, and 35). Survival, larval duration and megalopa size were compared between treatments. U. pusilla larvae developed optimally in the highest salinity (35) and higher temperatures (23–28°C). Low salinities and temperatures did not support larval survival and development, with salinity being the main restricting factor for survival, while temperature affected mainly the duration of the larval stages. Larvae at higher temperatures (23–28°C) presented a higher development rate but no differences were found in megalopa size. 相似文献
16.
H.J. Clarke J.G. Wilson I. Kuo M.M. Lülsdorf N. Mallikarjuna J. Kuo K.H.M. Siddique 《Plant Cell, Tissue and Organ Culture》2006,85(2):197-204
The main constraint to the transfer of desired traits into cultivated chickpea from wild Cicer relatives is the presence of post-zygotic barriers which result in abortion of the immature embryo following interspecific hybridisation. Rescue of hybrid embryos in vitro and regeneration of hybrid plantlets could allow chickpea breeders to transfer desirable traits from wild relatives of chickpea. The development of embryo rescue techniques using selfed chickpea and selfed wild relatives is being used as a first step to protocols for wide hybrids. Optical microscopy studies of embryogenesis, in both selfs and hybrids, identified deleterious changes in the fertilised hybrid seed as early as 2–4 days after pollination in some crosses. These observations suggest that the appropriate time to rescue chickpea × C. bijugum hybrids is at the early globular stage of embryogenesis (2–7 days old), which requires the development of a complex tissue culture medium. In contrast hybrids between chickpea × C. pinnatifidum abort later (up to 15–20 days old) at the heart-shaped or torpedo stages, and are easier to rescue in vitro. Genotype also plays a significant role in the ability of immature selfed ovules to germinate in vitro. In this paper we report on the optimisation of␣protocols for rescueing immature embryos using selfed chickpea and its wild relatives in ovule, and subsequently to regenerate plantlets. 相似文献
17.
The success of all insect societies relies on their ability to maintain optimal levels of different castes. Here we report
on an apparent free-running circannual rhythm that optimizes the developmental time of the soldier caste of Coptotermes formosanus Shiraki. Over a 3 year period, bioassays were conducted each month (except June) with groups of 100 termite workers in a
28°C incubator in total darkness. The number of days needed for C. formosanus soldiers to develop varied depending on the time of the year (month). In March, just prior to the major swarming exodus for
alates (April to June), 9 days were required before a worker molted to a presoldier. Longer times were required for such a
molt in all other months, with an increasing trend from April to December (from 13 to 30 days) and a decreasing trend from
January to February (from 25 to 12 days). Colony origin or the length of time that termites were kept in the laboratory under
constant conditions (26 – 28°C, 70 – 80% RH) before testing (7 days – 1 year) did not affect this rhythm. This is the first
demonstrated evidence of a free-running circannual rhythm in a social insect.
Received 23 July 2007; revised 9 and 21 August 2007; accepted 23 August 2007. 相似文献
18.
Reproductive aspects ofAlopias superciliosus in the northwestern Pacific were described in detail, on the basis of 629 specimens (429 females and 200 males) collected
from January 1984 to October 1984 and from October 1992 to March 1994.Alopias superciliosus embryos are oophagous. Six developmental stages (3 encapsulative and 3 posthatching) based on embryonic morphology and source
of nutrition were recognized. The species bears 2 embryos per litter, their size at birth being between 135 and 140 cm TL.
The sex ratio of embryos was 1∶1. Total length of females at maturity was 332–341. 1. cm; of males 270.1–287.6 cm. The gestation
period could not be determined because most adult females were pregnant throughout the year. The typical reproductive strategy
ofA. superciliosus is the production of a few large embryos per litter, with no fixed mating or birthing season. 相似文献
19.
The embryonic, larval and juvenile development of blue whiting,Sillago parvisquamis Gill, are described from a series of laboratory-reared specimens. Mean egg diameter and mean total length (TL) of newly-hatched
larvae were 0.71 mm and 1.58 mm, respectively. The eggs were non-adhesive, buoyant and spherical with an oil globule (mean
diameter 0.18 mm). Hatching occurred about 20 hours after fertilization at a temperature of 24.0–25.0°C, newly-hatched larvae
having 38–40 myomeres. The yolk and oil globule were completely absorbed 3 days after hatching at 2.8–3.2 (mean 3.0) mm TL.
Notochord flexion was completed by 7.2–8.2 (7.7) mm TL, and pectoral and caudal fin rays fully developed by approximately
10 mm and 8.5 mm TL, respectively. Completion of fin development occurred in the following sequence: caudal, pectoral, anal
and second dorsal, first dorsal and pelvic, the last-mentioned by approximately 11 mm TL. The larvae ofS. parvisquamis andS. japonica, which closely resemble each other in general morphology and pigmentation, could be distinguished as follows. Newly-hatchedS. parvisquamis larvae had more myomeres thanS. japonica (38–40 vs. 32–34) and more melanophores on the dorsal surface of the body (19–28 vs. about 40).Sillago japonica had a vertical band of melanophores on the caudal peduncle, which was lacking in postflexionS. parvisquamis larvae. In addition, juveniles ofS. parvisquamis (larger than 23 mm TL) had melanophores on the body extending anteriorly to below the lateral line to form a midlateral band,
whereas no obvious band occurred on similarly-sizedS. japonica juveniles. 相似文献
20.
Factors affecting microspore embryogenesis of cow cockle (Saponaria vaccaria) were evaluated including donor plant growing conditions, genotype, bud size, density, medium composition, and culture conditions.
Of the two donor plant (day/night) temperature regimes evaluated (10/5°C and 20/15°C), plants grown at 20/15°C were the most
embryogenic. An embryogenic frequency of greater than 350 embryos/100 buds was observed in the most embryogenic genotype,
cv. ‘White Beauty’. Buds from 3–9 mm in length were evaluated for their embryogenic potential; buds that were 4–7.9 mm produced
the most embryos/100 buds. Of all the media compositions evaluated, NLN medium with 15% sucrose resulted in the most embryos.
Cow cockle microspores required an initial period of 32°C for 3 days for production of microspore-derived embryos (MDEs). 相似文献