ISSN:0022-104X    

DOI:10.1002/jez.1401870102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractFractions of sperm homogenates from various animals (medaka, loach, toad, and rat) have been injected into unfertilized mature eggs of the medaka,Oryzias latipes, to test their cleavage‐initiating activity (CIA). The relationship between CIA and components of each fraction was also examined by observation with an electron microscope. It was found that there was high CIA in the fraction containing flagella or microtubules, but little CIA in the supernatant fluid without them. The CIA was closely related to the concentration of flagellum components and had no species‐specificity. However, further development after the blastula stage might be influenced by a species‐specific factor(s) of some flagellum compo

ISSN:0022-104X    

DOI:10.1002/jez.1401870103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractPresent investigations were carried out in an effort to determine the mechanisms in avian Müllerian duct differentiation, especially those responsible for the asymmetrical differentiation in female embryos. Ultra‐structural study of events during quail development demonstrated the following: At an early embryonic stage, a central simple‐layered epithelial canal was thickly enclosed with loose connective tissue whose fibroblasts resided in interlacing feeble networks. These fibroblasts appeared to migrate easily while maintaining tenuous contacts by slender cytoplasmic processes. At later stages, the loose connective tissue became denser and more concentrated near the canal. Fixed fibroblasts were surrounded by bundles of self‐elaborated collagen fibers completing a tight commissure with the basement membrane of the epithelium in the left duct, but a tight commissure was not completed in the rudimentary right duct.Corresponding to ultramicroscopical features, collagen synthesis was estimated by3H‐proline incorporation to be comparable to the14C‐amino acids incorporated during duct differentiation. Specific activities revealed an apparent asymmetrical differentiation between the left and right ducts at an early embryonic stage when differences between both the ducts could hardly be discerned by electron microscopy. These incorporations in vitro were affected by the presence of estradiol at physiological concentrations and, indeed, exhibited certain differences between the left and right ducts in response to the presence of

ISSN:0022-104X    

DOI:10.1002/jez.1401870104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractPectinatella gelatinosahas only one generation of statoblasts a year. The statoblasts are dormant when they are formed in summer. When they were kept in water under laboratory conditions, dormancy was gradually broken from late autumn to early spring of the following year. No effective means was found to induce germination in the dormant statoblasts. Some substance(s) which inhibits the germination of statoblasts, hence called blastostasin, was demonstrated in the water in which statoblasts had been stored for a long period. The optimum temperature for germination is about 25°C. Light is an essential factor but is needed for only the initial phase of germination. Prolonged periods of illumination with strong light are inhibitory. Visible light with wavelengths longer than green is effective for germination. Undried statoblasts remained viable for more than three years. Some germination was also obtained from statoblasts dried for 20 months. Undried statoblasts can resist prolonged periods of freezing but are very sensitive to high temperature.It is suggested that the effectiveness of critical experimental factors varies with the previous history of statoblasts. Various unfavorable, but not lethal, treatments resulted in temporary loss of germinability and brought the statoblasts into a resting state, for which the term “induced dormancy” is prop

ISSN:0022-104X    

DOI:10.1002/jez.1401870105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractDuring the larval‐pupal transformation of the cecropia silkmoth, the concentration of magnesium in the fat body declines from about 40 to 20 mEq/I cell water, while intracellular trehalose drops to a similar extent. Among fullygrown larvae and early pharate pupae, the hemolymph trehalose level (which is close to the fat body trehalose level in these stages) is correlated with the concentration of magnesium in the fat body but not with that in the hemolymph.Injection into larvae, of sufficient magnesium chloride to double the magnesium content in the hemolymph, did not lead to elevated magnesium in the fat body.It is concluded that the concentration of magnesium in the fat body is regulated independently from that in the hemolymph. Since the trehalose phosphate synthetase is activated by magnesium, the concentration of magnesium in the fat body may play a significant role in regulating the rate of synthesis, and hence the steady state level, of trehalos

ISSN:0022-104X    

DOI:10.1002/jez.1401870106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe formation of positional information in cells involves the determination of a geometrical point pattern in a developing system. The translation of genetic information into a spatial pattern is achieved in the unicellular ciliateChilodonella cucullulusby the two‐dimensional cortical surface which specifies a non‐random distribution of continuously dispersed organelles during the early stage of divisional morphogenesis.The supposed mechanism of positioning operates in a system of spatial coordinates and the system possesses definite reference points and boundaries. One reference point is the site of the oral apparatus. This site, at the stage of early divisional morphogenesis ofChilodonella, acts as a source of positional information specifying the sites of the daughter reference points (centers). These centers specify the sites of differentiation of primordia of the contractile vacuole pores (CVPs). This positional information is regulated by the boundaries of the ventral surface and the topography of the postoral sector. Specified sites of differentiation may be shifted somewhat eventually by structural guidance factors.Inter‐ and intraclonal polymorphism of C.cucullulussuggests that a genie basis for parameters of positioning also exists.The congruence between the model of positional information in multicellular systems (Wolpert, '69, '71) and the analysis of morphogenetic pattern in C.cucullulusis discussed. The cell surface membrane is envisaged as the possible structural site of the mechanism of positi

ISSN:0022-104X    

DOI:10.1002/jez.1401870107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractFemale chicks carrying a recessive lethal, sex‐linked gene designatedpx(paroxysm) develop seizures. In a population ofpxchicks (hemizygous females), the mean age of showing the first seizure is 19 days. The seizure syndrome can be generally divided into four phases: (1) alert phase (vocalization and/or running), (2) clonic phase (wing flapping, legs flex), (3) tonic phase (opisthotonos), and, (4) recovery phase. Seizures are spontaneous and recurrent but can also be precipitated by various environmental stimuli or by electrical stimulation of brain. Electroencephalogram recordings during seizures consistently show repetitive high amplitude spikes. Dilantin and sodium pentobarbital were effective in inhibiting electrically induced convulsions. No gross brain lesions were detected with light microscop

ISSN:0022-104X    

DOI:10.1002/jez.1401870108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractMale European starlings (Sturnus vulgaris) were held in constant darkness for 448 days. Testicular widths, measuredin situvia unilateral laparotomy at two to four week intervals, revealed that testicular growth reached a size associated with spermatogenesis in an average of 101 days. The spermatogenic period persisted for an average of 296 days. Histological examination of testes from two birds after 280 days of treatment revealed mature sperm in the seminiferous tubules. Complete testicular involution did not occur. Current photoperiodic theory must be modified to explain testicular metamorphosis without daily photostimulation in an avian species known to be photoperiodic.

ISSN:0022-104X    

DOI:10.1002/jez.1401870109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractFour‐day oldDrosophila melanogasterhomozygous or hemizygous for the glucose‐6‐phosphate dehydrogenase mutant allele,Zw−, possess slightly less than 10% as much glucose‐6‐phosphate dehydrogenase activity in whole‐fly homogenates as their wild‐type,Zw+, counterparts. The reduction of glucose‐6‐phosphate dehydrogenase activity inZw−adults had no effect upon 6‐phosphogluconate dehydrogenase, phosphofructokinase, or malic enzyme activities. However, activities of the non‐oxidative pentose shunt enzymes were significantly greater inZw−adults than inZw+adults. Radiotracer procedures indicate that the oxidative phase of the pentose shunt is blocked inZw−adults.Zw−larvae grow less well on a defined minimal amino acid diet lacking fatty acids and whole nucleic acid than doZw+larvae, indicating thatZw−individuals have a lower biosynt

ISSN:0022-104X    

DOI:10.1002/jez.1401870110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractInorganic and organic constituents were studied on blood serum collected from a living specimen of the coelacanth,Latimeria chalumnae. Inorganic electrolytes determined included sodium (196.7 mM/l), potassium (5.78 mM/l), magnesium (5.30 mM/l), calcium (4.94 mM/l), chloride (186.7 mM/l), bicarbonate (9.60 mM/l), phosphate (5.08 mM/l), and sulfate (4.80 mM/l). Serum urea (377 mM/l) and trimethylamine oxide (122 mM/l) were high as previously reported, and accounted for the bulk of the total non‐protein nitrogen (1199 mg%); total amino acids added a small but not insignificant fraction (21.9 mg%). High serum lactate (16.5 mM/l) and glucose (6.57 mM/l) levels were probably indicative of stress; glucose was the only carbohydrate present in appreciable amounts in the serum, although traces of glucuronic acid and rhamnose were found. Serum total cholesterol was 3.91 mM/l, organically bound phosphorus 1.99 mM/l and total proteins 2.84 g%. Three major protein fractions were evident from cellulose acetate electrophoresis and at least 11 peaks were demonstrable by acrylamide gel electrophoresis.Latimeriaserum lacks a protein component with a mobility approaching that of human serum albumin. Serum osmolarity (932 mOsm/l) was somewhat lower than that of sea water collected at the site of capture of the specimen (1035 mOsm/l). Evolutionary implications of the similarity ofLatimeriaserum chemistry to that of other marine fishes are discusse

ISSN:0022-104X    

DOI:10.1002/jez.1401870111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY