摘要:

AbstractThe specific activity of malate dehydrogenase isozymes in cytoplasm and mitochondria of liver and heart have been studied throughout development in the chick. The properties of the isozymes in these tissues are similar to those reported for other tissues. During development, the pattern of the specific activity of the isozymes of liver differs from that of the heart. Activities of the mitochondrial matrix and cytoplasmic isozymes of liver are constant; in heart they increase but not to the same extent. In mitochondria, the activity of malate dehydrogenase varies in the same way as that of cytochrome oxidase. Like cytochrome oxidase, malate dehydrogenase is therefore a constant proportion enzyme. Glutamate dehydrogenase is found in significant amounts in the liver; it is localized in the mitochondrial matrix, and its specific activity remains constant throughout development. In contrast, glutamate dehydrogenase can be detected in the heart only after hatching.

ISSN:0022-104X    

DOI:10.1002/jez.1401740202

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

年代:1970

数据来源: WILEY

摘要:

AbstractCytological studies of ovaries fromDrosophila melanogasterhomozygous for the third chromosomal, female sterile gene,suppressor2of Hairy‐wing (su2‐Hw), demonstrate that the nurse cell components of the egg chambers are primarily affected. Both chromosomes and nucleoli show qualitative and quantitative differencies from wild type. Thein vitroculturing of mutant and wild type ovaries in the presence of labeled RNA and protein precursors were examined using liquid scintillation counting and autoradiography. The results of the scintillation experiments showed the mutant ovary to be nearly equivalent to wild type in the synthesis of RNA, but only half as active in protein synthesis. The autoradiographic analysis revealed that during very short incubation periods, the mutant ovary was more active than wild type in the production of RNA but that the mutant RNA was unstable. The lowered protein synthesis by mutant ovaries was also apparent using autoradiography. Morphometric measurements of mutant and wild type nurse nucleoli indicate a severe reduction insu2‐Hwcompared to wild type. These findings suggest that the instability of mutant RNA may be due to some deficiency of the ribosomes produced in the absence of thesu2‐Hw+allele. On the other hand, the autoradiographic studies using H3‐uridine revealed the presence of an extranuclear label in the mutant nucleus not apparent in wild type. The possibility exists, therefore, that the unstable mutant RNA is of extranucleolar origin and thus not ribosomal. In the absence of thesu2‐Hw+allele, translation occurs with poor fidelity leading to the suppression of the phenotypic effects of certain mutant genes. If the ribosomes are responsible for the instability of mutant RNA, normal ribosomes contributed by the heterozygous mother may allow the survival of homozygous m

ISSN:0022-104X    

DOI:10.1002/jez.1401740203

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

年代:1970

数据来源: WILEY

摘要:

AbstractPhotomicrographs of the cytological changes of the sperm head and of the female chromatin in the rabbit egg, from the time of sperm penetration and activation of the second meiotic metaphase up to the formation of pronuclei and syngamy, are presented. During a study on factors affecting sperm penetration of rabbit eggs, some anomalous eggs were observed. One unfertilized egg possessed two second meiotic metaphases and associated first polar bodies, while another similar egg had two first and two second polar bodies, two sets of female chromatin, and one fertilizing sperm. In this latter egg fertilization was apparently proceeding normally. Two eggs within a single zona pellucida were also seen; one of these was a primary oocyte, while the other was a normally penetrated egg. Evidence is also presented which indicates that the incidence of polyspermy (usually dispermy) is increased, if eggs enter the oviduct at 14 hours or later after mating. This is thought to be due to more fully capacitated sperm present at the site of fertilization at these later times, and thus there is a greater chance of two or more sperm entering the vitellus at the same time.

ISSN:0022-104X    

DOI:10.1002/jez.1401740204

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

年代:1970

数据来源: WILEY

摘要:

AbstractAn analysis was carried out on the number and location of conjunctival papillae and scleral ossicles in chick embryos homozygous for the recessive gene scaleless. There are, on the average, three conjunctival papillae per eye in the mutant, while normal embryos have 14. The mutant is also deficient in the number of scleral ossicles having an average of one ossicle per eye. The ossicles of scaleless mutants in contrast to normals, are variable in size and irregular in shape. They are found in the same region as the papillae which remain after nine days of incubation. Histological examinations indicate a general retardation of the scaleless conjunctival papillae.

ISSN:0022-104X    

DOI:10.1002/jez.1401740205

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe freezing point depression (ΔTf) of the plasma, uterine fluid and the fluid in the blastocyst cavity have been measured in pregnant rabbits at 4, 5, 6, 7 and 8 dayspost coitum. The sign and magnitude of the chemical potential gradients of water between the different compartments have been calculated from the mean values for the ΔTf. It is concluded that these gradients cannot account for the observed net water flows and that energy‐coupled processes must be involved. The energy available from respiration is far more than would be required for such energy‐coupled water

ISSN:0022-104X    

DOI:10.1002/jez.1401740206

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

年代:1970

数据来源: WILEY

摘要:

AbstractLactate dehydrogenase (LDH) isozyme 1 (B4), 5 (A4), and “X” (Testis or Sperm type) have been partially purified from mouse tissues.The following studies were carried out on the three isozymes: Kmand optimum substrate concentration for pyruvate, α‐oxo‐butyrate, α‐oxo‐valerate, lactate, α‐OH‐butyrate, and α‐OH‐valerate, inhibition by substrate and product, effect of malate, N‐(4‐carboxy‐2‐hydroxyphenyl) maleimide, some citric acid cycle metabolites, urea, trypsin and pH.The mouse testicular LDH isozyme clearly differs from the common lactate dehydrogenases and from the tesficular isozymes from other species. It shows distinct sensitivity to inhibition by substrate or product whether the direct (pyruvate → lactate) or reverse reactions are studied. There is no effect of increasing concentrations of pyruvate or lactate on the direct reaction, while a clear inhibition by lactate or pyruvate is demonstrated on the reverse reaction. Citric acid cycle metabolites, specially malate and succinate, inhibit the direct reaction catalyzed by the “X” isozyme.These peculiar characteristics suggest a high degree of specialization for the principal testic

ISSN:0022-104X    

DOI:10.1002/jez.1401740207

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

年代:1970

数据来源: WILEY

摘要:

AbstractMorphological aspects of nucleoli of iris epithelial cells participating in Wolffian lens regeneration in the adult newt (Triturus viridescens) were studied with electron and phase‐contrast microscopes at various times after lens removal. In normal condition, the nucleoli appear as small, compact bodies composed of fibrous elements. The granular element is often lacking, but when present, is sparse and located at the periphery of the organelle. Within two days after lens removal, the size of the nucleolus increases, and its shape becomes complex and diversified. The granular element increases in absolute as well as relative amount. Granular and fibrous components become intermingled and together form the fibrogranular region. Portions of this region often project from the nucleolus as coarse threadlike extensions that become a prominent feature. Morphogenesis of the organelle continues during the subsequent two days. In parallel with these structural changes, the number of nucleoli per nucleus and the frequency of nuclei containing nucleoli increases. All these changes start in the nondividing phase of the iris epithelium before induced cell division. These changes in nucleoli are the earliest so far observed in iris epithelial cells after lens removal, and coincide in time with the activation of ribosomal RNA synthesis previously observed in this syste

ISSN:0022-104X    

DOI:10.1002/jez.1401740208

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe action of gonadotropins (FSH, LH, PMS, and HCG) and testosterone on the initiation of spermatogenesis was studied in the Indian House LizardHemidactylusduring the non‐breeding season after pituitary ablation. Both ovine FSH and PMS initiated spermatogenesis leading to the formation of mature spermatozoa after 45 days while LH, HCG, or TP had no stimulatory effect on the testis. Synergistic action was not observed when FSH or PMS was injected in combination with LH, TP, or HCG as evidenced by the germ cell counts in the seminiferous tubules.The androgen‐dependent sexual segment of the kidney was also fully developed in the animals treated with FSH or PMS. These results indicate that the initiation of gametogenic and androgenic functions in the testis of the Indian house lizard are dependent on an FSH‐like pr

ISSN:0022-104X    

DOI:10.1002/jez.1401740209

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe swordtail (Xiphophorus helleri) eye contains the A4and B4isozymes of lactate dehydrogenase (LDH) as do all vertebrates and in addition contains a distinctive lactate dehydrogenase, the E4isozyme, found only in fish. LDH in the fish eye is located predominantly in the neural retina, especially in the inner segments of the photoreceptor cells. This neural retinal LDH activity consists mainly of the B4and E4isozymes which are more resistant than the A4isozyme to inhibition by 1.8 M urea. The sclera, cornea, and lens possess mainly the urea‐sensitive A4isozyme. The specific cellular location of the E4isozyme suggests that it plays a role in the biochemistry of visio

ISSN:0022-104X    

DOI:10.1002/jez.1401740210

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

年代:1970

数据来源: WILEY

摘要:

AbstractEpidermal material from a variety of reptilian species, avian and mammalian scales have been examined by standard histological and x‐ray diffraction techniques. It has been found that morphologic and/or tinctorial properties are not good criteria for the identification of specific fibrous protein types. The distribution of fibrous protein types in reptilian epidermal material is very variable, especially in turtles. Lepidosaurian reptiles (the tuatara, snakes and lizards) are unique in showing an alternating vertical distribution of feather and α‐type proteins over the entire body surface. The protein distribution in crocodilian scales resembles exactly that found on avian scales. Mammals only possess the α‐type protein whatever the nature of the epidermal structure of modif

ISSN:0022-104X    

DOI:10.1002/jez.1401740211

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

年代:1970

数据来源: WILEY