bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in testicular cholesterol associated with estrogen induced infertility in male mice
Authors: Simmons J. Emmett
Published: June 2005

Male mice were injected on the fifth postnatal day with 50 μg of estradiol undecylate and the changes in morphology and testis cholesterol were studied at 10, 20, 40, 60 and 90 days. Such treatment resulted in decresed body weight, atrophic testes and seminal vesicles, adrenal and pituitary hypertrophy, failure of scrotal development with crptorchidism, impaired spermatogenesis, and alopecia. The onset of these changes, however, occurred at different ages. Testicular atrophy was manifest as early as day 20, while seminal vesicle atrophy and adrenal hypertrophy were not apparent until day 40, and a decreased body weight and alopecia were observed by day 60. Pituitary hypertrophy was observed at only day 90.

There were no significant differences in total testicualr cholesterol between estrogenized and control mice at ten days. However, at all other stages studied experimental animals had significantly more cholesterol than their oil injected controls. This increase in cholesterol within the testes of estrogenized mice is interpreted as decreased utilization of cholesterol for steroidogenesis. That there was a lack of endogenous androgen in these estrogenized mice as late as 90 days was indicated by atrophic seminal vesicles and the presence of an x‐zone in the adrenal gland.
Effects of the deafferentation of the trigeminal area on the motility of the chick embryo
Authors: Hamburger Viktor , Narayanan C. H.
Published: June 2005

The neural crest and placodal primordia of the trigeminal ganglion were extirpated bilaterally at stages 11–12. Tests of the tactile sensitivity of different head regions showed the absence of responses to stimulation in 31 of 35 deafferented embryos. In a histological study of eight randomly selected experimental embryos small residual ganglia and trigeminal nerves were found; however, they were apparently functionally ineffective. Midbrain and cerebellar defects were found in 60% of the embryos.

Periodic motility was recorded mechanically, as in previous studies, in embryos between 9 and 17 days. Random motility up to 15 days was not different in normal and deafferented embryos. This implies that self‐stimulation of the head, for instance, by brushing of legs or wings against the head, or proprioceptive self‐stimulation, play no role in the random motility at least up to 15 days. A decline of spontaneous motility which occurs in normal embryos after 17 days, begins in experimental embryos already at 15 days. This may be due to the absence of sensory input or, at least in the majority of cases, to the above‐metioned brain damage.

The operated embryos did not hatch but remained in a position characteristic of the 17‐day stage. The failure to perform the integrated prehatching and hatching behavior may be due to either one of the following causes: (1) Absence of specific sensory information; (2) Absence of non‐specific excitatory stimulation reducing muscle tonus; (3) Transneuronal degeneration in trigeminal medullary or in higher centers; (4) Damage in the midbrain and/or cerebellum.
Ontogeny of the immune response to skin allografts in relation to lymphoid organ development in the amphibian Xenopus laevis Daudin
Authors: Horton John D.
Published: June 2005

The response of larval and adult Xenopus to first set skin allografts was studied by examination at regular intervals of the external appearance of the grafts and of serial sections through the graft region. Operations were performed on all stages of larvae ranging from those with rudimentary to those with mature lymphoid organs. Larvae received single allografts from either larval or adult donors, skin from the latter being a good morphological marker: adults received adult skin only. Control autografts were also applied to both larval and adult toads.

All autografts were accepted; no incompatible phenomena were observed. Both adults and larvae, even those operated at the most immature stage of development, were able to repond immunologically to the skin allografts. The response was similar in larval and adult toads and included a lymphocytic invasion of the graft which disappeared when destruction of the graft was near completion. This invasion was correlated with the state of development of the lymphoid organs of the host: if these organs were immature at the time of application of the graft, the invasion was delayed but eventually occurred when the host reached a more advanced larval stage. The capacity to invade a graft with lymphocytes could be correlated with the lymphoid maturation of the thymus.

These results support the view that the allotransplantation of tissues in immature amphibian larvae, before acquisition of immunological competence, does not necessarily preculude the possibility of an immune response to the same tissues in more mature larvae.
Chronic allograft rejection in Lumbricus terrestris
Authors: Cooper Edwin L.
Published: June 2005

To determine the capacity of earthworms to reject tissue transplants, first‐set orthotopic allografts of body wall were exchanged between 280 adult Lumbricus terrestris. In addition, 30 worms were autografted as controls. Both auto‐ and allogeneic tissue transplants healed in promptly; autografts survived permanently while allografts showed varying degrees of incompatibility. Intrapopulation allografts in worms from Canada showed 22% permanently surviving transplants while 95% were not destroyed in the Oregon group; the remaining allografts in both groups were completely destroyed after prolonged chronic periods or showed incomplete rejection after observations during eight and one‐half months. No intrapopulation Oregon transplants were rejected completely while only 1% were in the Canadian group. About 5.5% of interpopulation allografts were destroyed on Oregon hosts and 15.3% on Canadian recipients between 38 and 153 days after grafting. Therefore, recognition and rejection of tissue allo‐antigens are characteristic of the primitive immune response of annelid worms.
Terminal respiration in minute mutants of Drosophila
Authors: Farnsworth M. W. , Jozwiak J.
Published: June 2005

Oxidative phosphorylation was studied in mitochondria isolated from third instar larvae heterozygous for the following Minute mutations: M(2)S‐10, M(2)l2, M(2)l, M(3)Y and M(3)l. The substrates utilized inculded α‐ketoglutarate, pyruvate with malate, succinate, α‐glycerophosphate and ascorbate. Mitochondria from an additional mutant, M(2)z, were also tested for their ability to metabolize α‐glycerophosphate. Abnormalities associated with the cytochrome b‐c site of phosphorylation were evident in all mutant genotypes. Additional lesions at the substrate level and at the DPN‐DPNH site of phosphorylation in the electron transport system were also identified in one or more of the mutants analyzed.
Chronology of spermatogenesis and spermiogenesis in poeciliid fishes
Authors: Defelice Diane A. , Rasch Ellen M.
Published: June 2005

Analysis by autoradiography after a single pulse label with 3H‐thymidine was used to mark the chronology of cell progression through spermatogenesis and spermatid differentiation in the ovoviviparous teleost fish, Poecilia sphenops, the aquarists' “black molly.” A minimum of 21 days was required from initiation of meiotic prophase to the development of mature, aggregated sperm. An additional two weeks elapsed during transport of sperm through testicular ducts, so that shed spermatophores with labeled sperm were found only after 35 or more days following isotope injection. Time estimates for various stages of spermiogenesis were independently confirmed by assessment of the duration of elapsed time using frequency of occurrence of particular stages within the total population of testicular crypts as an index of relative elapsed time.
Effects of mammalian gonadotropins on the ovaries and oviducts of the lizard, Lygosoma laterale
Authors: Jones Richard E.
Published: June 2005

Female Lygosoma laterale with quiescent ovaries and oviducts were treated with 1.0 I.U. of either FSH, LH, FSH plus LH, PMS or HCG daily for 15 days to elucidate their effects on the reproductive tract. FSH increased ovary and oviduct weight and follicle diameter, but its effects were antagonized by LH. Neither HCG nor LH had an effect on ovary weight or follicle diameter, and both only slightly increased oviduct weight. The effects of PMS were similar to those of the FSH‐LH combination, both causing a moderate increase in ovary and oviduct weight and follicle diameter. These results are discussed in relation to the effects of exogenous mammalian gonadotropins in other reptiles and in mammals.
Effect of actinomycin D on antigen synthesis during sea urchin development
Authors: Westin Monica
Published: June 2005

Eggs and developmental stages of the sea urchin Paracentrotus lividus were incubated with radioactive (14C) amino acids. Incorporation of label into antigen was studied by means of rabbit antisera against sea urchin material. In an attempt to block genetic control of protein synthesis, eggs and embryos were treated with actinomycin D during different periods of development.

During normal development the antigen‐labeling pattern, studied by immunoelectrophoresis and autoradiography, remained essentially unchanged until hatching. In the mesenchyme blastula, however, a new labeled antigen was detected, and one which earlier was unlabeled became heavily labeled. As seen in autoradiographs, during the same period, the intensity of labeling of other antigens also changed. When the embryos were exposed to actinomycin D (10–20 μg/ml) from hatching or some hours before, the development stopped at the mesenchyme blastula stage and these embryos never developed the labeling pattern characteristic of normal mesenchyme blastula.

The results suggest that in contrast to the early development, gastrulation requires new production of templates. These templates seem to be essential for the changing pattern of antigen‐labeling. It is suggested that alterations in amino acid incorporation into antigens reflect changes in synthesis of proteins necessary for gastrulation.
Amylase variants in Drosophila melanogaster: Linkage studies and characterization of enzyme extracts
Authors: Doane Winifred W.
Published: June 2005

The amylases of D. melanogaster were characterized by several parameters. Starch‐iodine and 3,5‐dinitrosalicylic acid reduction methods were employed to determine activity. Conditions were defined under which activity, in crude aqueous extracts could be restricted to α‐amylase(s) of fly origin. Biochemical properties of the α‐amylases from eleven homozygous Amy strains were found to be very similar in temperature stability, pH optimum, substrate specificity and the effects of various activators and inhibitors. All were activated by chloride ions and showed a pH optimum of about 7.4. Relative efficiencies on several substrates were tested: soluble starch, amylopectin, β‐limit dextrins, glycogen and amylose. EDTA completely inhibited all extracts, presumably by the removal of calcium required for activation. The specific α‐amylase inhibitor from wheat grain also completely inhibited activity, as did reduced glutathione. PCMB had no discernible effects on activity.

Eight of the 11 strains tested are known to produce different electrophoretic banding patterns for amylases. The total maximum activity of each strain may also be used to characterize it and, accordingly, three strains with amylases of the same electrophoretic mobility were distinguished by differences in their specific activities. Sexual dimorphism in amylase activity was defined, as well as activity in heterozygotes between strains. Aside from the distinctions between strains already noted, four strains differed in their relative susceptibility to heat and to α‐amylase inhibitor.

Linkage experiments indicated that the Amy region lies at 77.3 on the genetic map of the second chromosome and to the right, but near, section 52F on the salivary chromosome map.
Electrophoretic variations of tyrosinase in follicular melanocytes during the hair growth cycle in mice
Authors: Burnett Jean B. , Holstein Thomas J. , Quevedo Walter C.
Published: June 2005

Multiple forms of tyrosinase separable by acrylamide‐gel electrophoresis are demonstrable in extracts of hair bulbs prepared on the fifth (anagen IV) through the thirteenth days (anagen VI) of a hair growth cycle induced in C57BL/6J mice by plucking of quiescent hairs. The enzymic bands visualized by incubation of the gels in L‐DOPA have been designated as T1, T2 and T3. Although T1 has been observed through day 19, the T2 and T3 components disappear by day 15 of the hair growth cycle. Tyrosinase activity is not demonstrable in skin extracts prepared during telogen or on days 1–3 post‐plucking (anagen I–III). The slow development of a single DOPA‐melanin band in such samples has been demonstrated to represent non‐specific oxidation by hemoglobin that migrates at a slightly slower rate than the T3 component. The precise state of tyrosinase within follicular melanocytes prior to day 5 of the hair growth cycle remains to be determined. The functional significance of the multiple forms of tyrosinase also is yet to be established.
Postural control of shell position by the abdomen of the hermit crab, Pagurus pollicarus. II. Reflex control of the ventral superficial muscles
Authors: Chapple William D.
Published: June 2005

The five excitors and one inhibitor which innervate each side of the ventral superficial muscles of the hermit crab are described. The longitudinal layer receives three excitors, one of which phasically activates a lateral strip of muscle, the second tonically drives a ventromedial strip and the third innervates a strip between the other two. The inhibitor innervates the last two regions of longitudinal muscle as well as the circular muscle. Two excitors, a phasic and a tonic fiber innervates adjacent longitudinal regions of the circular muscles, but less is known of their reflex behavior. In all cases, the tonic frequency of units on the right was less than their homologues on the left, but this asymmetry was reversed during a reflex discharge. Isolation of the ganglion increased the asymmetry of spontaneous activity. It is suggested that this asymmetry may not have any functional importance but instead may be related to the different sizes of motoneurons on the two sides.
Postural control of shell position by the abdomen of the hermit crab, Pagurus pollicarus. III. Analysis of movements and calculations of forces exerted by the muscles
Authors: Chapple William D.
Published: June 2005

Experiments with a transparent plastic snail shell indicated that the hermit crab carries the columella in the crook of its bent abdomen. There are three components to the normal curvature of the abdomen in the region of the third segment, a ventroflexion of 30°, a pitch to the right of 10°, and a clockwise rotation of 20° of the whole abdomen about the thoracic‐abdominal junction. The forces and bending moments produced by the ventral superficial muscles were estimated from the sizes of the muscles, their position on the circumference of the abdomen, the amplitudes of the EJPs of the motoneurons, and their firing frequency. These calculations are in reasonable agreement with the behavioral measurements.
Development of transferred ferret eggs in relation to the age of corpora lutea
Authors: Chang M. C.
Published: June 2005

Ferret eggs recovered from oviducts and uteri at various times after insemination were transferred to the uteri of recipient animals on various days of pseudopregnancy. Fifteen per cent of newly fertilized two day eggs recovered from oviducts were implanted when transferred to uteri of two‐day pseudopregnant ferrets but only 5% developed to fetuses. Synchronous transfer of four‐, six‐, seven‐ and eight‐day eggs to uteri of four‐, six‐, seven‐ and eight‐day pseudopregnant ferrets resulted in 44‐62% of implantations, but only 21–41% of eggs developed to fetuses. Twenty‐one‐fifty‐seven percent of eggs were implanted, and 8–29% of eggs developed to fetuses when eggs were transferred to uteri of ferrets that had ovulated two days later. When transferred to uteri of ferrets that had ovulated two days earlier none developed to fetuses although 33–50% of transferred eggs implanted. No fetal development was observed when six‐day eggs were transferred to estrous ferrets treated with various progestins, but a few implantations (3–17%) occurred.
Lactate dehydrogenase lsozymes of the penguin Pygoscelis adeliae
Authors: Markert Clement L. , Mausi Yoshio
Published: June 2005

The complex isozyme patterns of lactate dehydrogenase (LDH) in penguin (Pygoscelis adeliae) tissues were examined at several successive stages in embryonic development by starch‐gel electrophoresis. The relative quantities of the isozymes were measured by densitometry, and the subunit composition of each isozyme was analyzed by molecular hybridization. The complexity of the isozyme pattern varied greatly with the conditions of electrophoresis but maximum resolution was obtained with a neutral Tris‐citric acid buffer of low ionic strength. When electrophoresis was carried out with this buffer at 4°C, as many as fifteen isozymes were resolved. Only five isozymes can be distinguished at high ionic strength. The fifteen isozymes can be classified into five groups, each group corresponding to one of the five major LDH isozymes found in mammals and birds. The validity of this classification was tested by molecular hybridization with beef and horse LDH, the subunit composition of which is known. The pattern of hybrid molecules produced suggests that penguin LDH contains three different subunits that may generate fifteen isozymes by random association as tetramers. To test the binomial proportions among the isozymes a quantitative photometric assay was developed for measuring enzyme activity in terms of formazan deposited on a starch gel during the staining reaction for LDH. Only at low enzyme concentrations is the deposited dye linearly proportional to the amount of enzyme. The relative abundance of the isozymes in most tissues approximated a binomial distribution. Tissue spcific patterns revealed that anodal isozymes predominate in heart, ovary and liver and cathodal isozymes in lung and muscle. However, in contrast to mammalian tissues, the penguin patterns are not sharply skewed. All isozymes are reasonably abundant in all adult tissues. In early embryonic stages of development all tissues contained greater proportions of LDH‐1, but a shift in isozyme distribution gradually took place during the course of development to enrich enzyme activity at the LDH‐5 end of the spectrum in late embryonic and adult tissues.
Reversible effects of antimitotic agents on cortical morphogenesis in the marine ciliate Condylostoma magnum
Authors: Tartar Vance , Pitelka Dorothy R.
Published: June 2005

Effects of antimitotic agents on morphogenesis in the marine ciliate Condylostoma were tested. Surgically transected cells or early predividers were placed in solutions of Colcemid, colchicine, vinblastine, griseofulvin, or chloral hydrate in varying concentrations and for varying periods of time. Although early dividers proceeded to complete cytokinesis and, in at least some instances, macronuclear fission while in the drug solutions, development of normal form and oral organelles in daughter cells and regeneration and remodeling in operated fragments were completely blocked by appropriate drug concentrations. Inhibition was in almost all cases reversible: blocked cells, when washed and returned to sea water, underwent normal morphogenesis.

Like other ciliates, Condylostoma has in its ectoplasm highly organized systems of microtubules associated with kinetosomes of the body ciliature and the oral apparatus. Electron micrographs of Colcemid‐treated cells show that preexisting cortical microtubules are not destroyed by treatments that prevent morphogenesis. They thus resemble ciliary and kinetosomal microtubules of other cells in being resistant to agents that cause the disappearance of most cytoplasmic and spindle microtubules.

Most of the recognizable events of morphogenesis involve the growth and migration of microtubular organelles, and these events did not occur in the presence of the inhibiting agents. It is concluded that microtubule growth is necessary for the development of structure and pattern in Condylostoma.
Effects of bilateral limb‐bud extirpation on motility and prehatching behavior in chicks
Authors: Helfenstein Myrna , Narayanan C. H.
Published: June 2005

The role of sensory input in the performance of overt motility by the chick embryo has been a matter of controversy. Although it has been proven that embryonic motility is generated in the motor system of the spinal cord and does not require sensory input up to 15 days, it has been suggested that self‐stimulation and related “experiences” during embryonic development are instrumental in the structuration or facilitation of normal embryonic and post‐hatching motor patterns. Using microsurgical techniques, hind‐limb buds were extirpated bilaterally in chick embryos at three days of incubation in order to eliminate a major source of self‐stimulation to the head by the legs. The total motility of legless chicks in not significantly different from that of the control embryos between 11 and 17 days. Part of the pre‐hatching and hatching behavior repertory is also performed normally by the legless embryos. However, they do not hatch, probably because the bracing of the tarsal joints against the shell is necessary for the rotatory movements during hatching. Feeding, drinking and righting after hatching are normal.
Modification of regeneration in Dugesia tigrina by actinomycin D
Authors: Ansevin Krystyna D. , Wimberly Marilyn A.
Published: June 2005

Differences in regeneration of isolated postpharyngeal body sections were observed in two laboratory groups of Dugesia tigrina. One group regenerated 14.8% of bipharyngeal specimens, which in some cases, also showed abnormal polarity. The other group regenerated only 1.19% of bipharyngeal forms under similar conditions, with no indications of seriously deviant polarity.

In the first strain, the application of actinomycin D at early stages of regeneration of the body sections increased greatly the incidence of multipharyngeal regenerates (with 2–5 pharynges); it also slightly enhanced the occurrence of abnormal polarity in the reconstituted worms. In the second strain, the increase in percentage of bipharyngeal forms regenerated from similar body fragments was insignificant (up to 5%). It was without effect on either strain if introduced to the regenerating sections at later stages of regeneraton. A test for incorporation of 32P into RNA showed that actinomycin, as used in the present study, suppressed over 90% of synthesis of total RNA in the regenerating body fragments.

From these findings a hypothetical model is developed to explain reorganization in the isolated postpharyngeal section as a sequence of certain local inductions and inhibitions of differentiation. The significance of synthesis of RNA in relation to these developmental events is discussed.
The degradation of lactate dehydrogenase isozymes injected into frog eggs
Authors: Rauch Nancy
Published: June 2005

Lactate dehydrogenase (LDH) isozymes from beef tissues were injected into newly fertilized frog eggs. Embryos at various stages were examined by starch gel electrophoresis to determine whether the injected isozyme was present. Beef LDH‐1 was stable for at least twelve days following injection, while beef LDH‐5 was present in the embryos as a functional molecule for less than six days. These very different in vivo stabilities are not in agreement with the in vitro stabilities obtained here, and suggest that regulated differential stability of isozymes may be important to the organism in conferring greater metabolic flexibility during cell differentiation when the isozyme repertory commonly changes. During the degradation of beef LDH‐1, no hybrid beef‐frog LDH molecules could be detected although such molecules can be formed by a simple in vitro technique. Since frog LDH is synthesized during the degradation of the injected LDH, the lack of detectable hybrid molecules indicates that the subunits of the degraded molecules cannot be reused—either because the molecule is degraded as a whole, without the release of subunits, or because the sites of synthesis and degradation are mutually inaccessible.
Effects of castration and/or hypophysectomy on the seminal vesicles of the catfish, heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Nayyar S. K.
Published: June 2005

The response of the seminal vesicles to hypophysectomy and/or castration during the prespawning and the spawning periods was studied. Forty days post‐hypophysectomy the seminal vesicles regress completely, whereas 40 days postcastration they show hyperactivity which is accentuated by 85 days post‐surgery. Further, catfish castrated in the prespawning period of 1966 not only show hyperactive seminal vesicles in that season but also exhibit hypersecretory seminal vesicles in the following breeding season, in spite of the absence of the testes. In the castrate catfish, hyperactivity in the seminal vesicles is accompanied by a significant increase in the number and activity of the granulated basophils in the pituitary and an increase in the nuclear diameter of the interrenal cortical cells. Two hypotheses are proposed to explain this paradoxical phenomenon.
The ultimobranchial body of Rana pipiens. X. Effect of glandular extirpation on fracture healing
Authors: Robertson Douglas R.
Published: June 2005

Fracture healing of the tibiofibula was examined in the frog, Rana pipiens, in which the ultimobranchial glands were removed. Extirpation of these structures presumably eliminates the hormone calcitonin. X‐ray and histological observations were made during the healing process of a closed fracture for a period of 12 weeks. The repair process of fractured bone in the first four weeks of intact and ultimobranchialectomized frogs revealed similar tissue reactions at the fracture site and followed comparable healing patterns. There was extensive cartilage formation in both groups with ossification at the periphery of diaphyseal cartilage. After eight weeks the fracture site of controls exhibited more extensive invasion and development of endochondral ossification than ultimobranchialectomized frogs. Osteoclasts were observed at the distal segment of the fracture, and throughout endochondral trabeculae. After 12 weeks, periosteal bone was well developed in controls, and poorly represented in ultimobranchialectomized frogs. Deprivation of calcitonin in frogs apparently does not affect cellular activity at a fracture site during the first four weeks. However, cellular activity is greatly reduced with a concomitant reduction in calcification after 8 and 12 weeks. This latter period corresponds to increased osteoclastic activity in ultimobranchialectomized frogs. Further, retarded repair process may also be influenced by serum calcium levels rather than by a lack of direct hormonal control on specific bone cells types.
Acid phosphatase in the tail of Xenopus laevis during development and metamorphosis
Authors: Robinson Helen
Published: June 2005

Quantitative and qualitative changes in acid phosphatase during growth and metamorphosis of the tail of Xenopus laevis have been investigated. Enzyme activity was assayed by two methods using different substrates, p‐nitrophenyl phosphate and β‐glycerophosphate. The enzyme was found to be consistently more active with p‐nitrophenyl phosphate. Specific activity of whole tail homogenates assayed by both methods remains constant during development and early metamorphosis, and then rises sharply as the rate of tail regression begins to accelerate. Total phosphatase activity of whole tail homogenates rises linearly during development and early metamorphosis, and then maintains a high level during the first half of the period of tail regression. After this it declines. Regional localization of acid phosphatase activity has been determined in different parts of the tail: dorsal fin, ventral fin, and muscle. Changes in the apparent Km and pH optimum of acid phosphatase occur during tail regression. These properties remain constant during development and early metamorphosis, and are then found to change approximately in parallel with changes in enzyme activity during tail resorption. Possible implications of these biochemical events are discussed.
Juvenile hormone effects on chromosomal puffing and development in Chironomus thummi
Authors: Laufer Hans , Holt Thomas K. H.
Published: June 2005

Several larval stages of the dipteran Chironomus thummi were treated with a synthetic juvenile hormone (JH) mixture. Treatment resulted in larvae which underwent the first three molts, but thereafter development was arrested; many were incapable of completing the larval‐pupal molt. The pattern of chromosomal puffs in the prepupal salivary gland was examined at 91 loci: nine pupal puffs which were consistently active in controls were found to be reduced following treatment; one puff, Balbiani ring IV b, was enlarged. Autoradiographs indicate intensive RNA synthesis at Balbiani ring IV b, but depressed synthesis at the other nine affected loci. The puffing pattern demonstrates for the first time in detail specific effects of chemical compounds with JH activity on chromosomal puffs. Compounds exhibiting JH activity may regulate transcriptional activity at specific gene loci, and specific alterations in RNA synthesis may account for alterations in the course of metamorphosis.
A role of inductive factors in interstitial cell differentiation in hydra
Authors: Lesh Georgia E.
Published: June 2005

The distribution of interstitial cells and I‐cell derivatives in hydra is asymmetrical. This asymmetry is expressed apico‐basally along the stalk and radially with respect to cell layer. An inductive factor concentrated from the tissues of hydra alters this expression of polarity (Lesh and Burnett, '66).

To test the hypothesis that quantitative differences in the concentration of this inducer effect qualitative differences in I‐cell differentiation, regenerating annuli were exposed to tissue extracts containing varying levels of inductive activity. Two types of extracts were employed: (1) serial dilutions of an active extract; and (2) extracts from different species of hydra exhibiting decreasing levels of inductive capacity. Hydra pirardi annuli were incubated four hours in extract. After 24 hours annuli were fixed, sectioned, stained, and counts made of all cell types.

Statistical analyses of these counts show that responding cell types demonstrate one or both of two responses: proliferation and/or differentiation. The initial response in normal annuli is a 1.9 ± fold increase in the proportion of I‐cells present. Annuli which undergo an increase in I‐cell complement before incubation develop alterations in the distribution of I‐cell derivatives. At concentrated inducer levels isorhiza cnidocytes (epidermis) and mucus cells (gastrodermis) differentiate. At lower concentrations stenotele cnidocytes and gland cells appear. The distribution of epithelio‐muscular cells and digestive cells (not I‐cell derivatives) is independent of inducer concentration.

Also, the distribution of I‐cells and derivatives found after the experimental treatments coincides directly with the distribution of these cell types relative to the inductive regions of intact hydra.
Differentiation of cartilage and bone from common germinal cells. I. The role of acid mucopolysaccharide and collagen
Authors: Hall B. K.
Published: June 2005

The differentiation of cartilage and bone from common germinal cells on the membrane bones of the embryonic chick has been investigated to test the hypothesis that acid mucopolysaccharides (chondroitin sulphate) and collagen play a role in controlling the pathways of differentiation open to the germinal cells. Injection of cortisone acetate was used to suppress sulphation of chondroitin to chondroitin sulphate and injection of vitamin C to stimulate collagen synthesis. Of the membrane bones studied 60–80% exhibited suppression of chondrogenesis, indicating that chondroitin sulphate and/or collagen play important roles in the control of chondrogenesis.

Mechanical stimulation and hypoxia have been related to chondroitin sulphate synthesis in proposing a mechanism to explain the differentiation of cartilage and bone from common germinal cells.
Alteration of nucleolar ultrastructure in iris epithelial cells during initiation of Wolffian lens regeneration
Authors: Dumont James N. , Yamada Tuneo , Cone M. Virginia
Published: June 2005

Morphological 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 system.
Localization of lactate dehydrogenase activity in the cells of the fish (Xiphophorus helleri) eye
Authors: Whitt Gregory S. , Booth Gary M.
Published: June 2005

The swordtail (Xiphophorus helleri) eye contains the A4 and B4 isozymes of lactate dehydrogenase (LDH) as do all vertebrates and in addition contains a distinctive lactate dehydrogenase, the E4 isozyme, 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 B4 and E4 isozymes which are more resistant than the A4 isozyme to inhibition by 1.8 M urea. The sclera, cornea, and lens possess mainly the urea‐sensitive A4 isozyme. The specific cellular location of the E4 isozyme suggests that it plays a role in the biochemistry of vision.
The cellular mechanism of the formation of a regeneration blastema of fresh‐water planaria, Dugesia dorotocephala. I. The behavior of cells in a tiny body fragment isolated in vitro
Authors: Betchaku Teiichi
Published: June 2005

Small fragments of 0.1 mm3 to 0.03 mm3, too small to regenerate the whole organism and yet containing a variety of tissues were taken from the prepharyngeal portion of a fresh‐water planaria, Dugesia dorotocephala. They were cultured in saline solution and histologically examined at intervals. Morphological rearrangement of tissues was completed in two days, coinciding with the time reported as necessary for the formation of an ordinary regeneration blastema. This was the result of the interactions of isotypically aggregating epidermis, gastrodermis and inner composite‐tissue, and involved neither dedifferentiation nor differentiation. The parenchyma accounted for most of the motility of the inner composite‐tissue layer. Furthermore, fixed parenchyma cells and neoblasts segregated in the portion of the parenchymal aggregate which was exposed to the saline solution, resulting in the aggregation of neoblasts in the periphery. This parenchymal segregation is considered due to differences in susceptibility to environmental conditions of these two parenchymal cells in addition to differences in motility and adhesiveness. The population of neoblasts thus aggregated was observed to increase by mitosis. A regeneration blastema appears to from by the local cellular segregation triggered by an injury under hypotonic conditions and not by the extensive migration of any particular cell type to the site of the wound. Less motile tissues, such as muscles and nerves, may account for the regional characteristics of the regeneration field. A possibility of involvement of the old tissues in the growth of a blastema and in its histogenesis is discussed.
Resting membrane potential in chick muscle cells during ontogeny
Authors: Boëthius Jörgen , Knutsson Evert
Published: June 2005

Resting membrane potentials were recorded from developing thing muscle cells of the chick at different stages from the third day of incubation. During the early stages the membrane potentials were lower than in the adult animal. No significant changes in potentials were observed until after the fifteenth day. There was a marked increase between the fifteenth and nineteenth days, and the membrane potential reached values comparable to those of the adult. In a study of the concomitant morphological development, the increase in membrane potentials was found to coincide with the transformation of the majority of the cells from myotubes to myocytes.
Sodium extrusion induced by ammonium ions in toad skeletal muscle
Authors: Beaugé L. A. , Ortiz Olga
Published: June 2005

A study was made of the ability of ammonium ions to stimulate active sodium extrusion in toad skeletal muscle. In sodium‐rich muscles, 15 mM ammonium induced a net loss of sodium against a concentration gradient slightly larger than 5 mM potassium. Similar results were obtained when a sodium efflux was considered. The activation curve of ammonium‐stimulated sodium efflux was strongly S‐shaped, reaching a plateau at 10–15 mM ammonium; this could be due to more than one activation site on the outside membrane, or to some cooperative effect of ions. The increment in the rate constant for sodium efflux produced by both ammonium and potassium was completely abolished by 10−4 M ouabain. The extent of the inhibition by a submaximal dose of this glycoside was independent of the external ammonium concentration up to 30 mM. This behavior corresponds to a non‐competitive type of inhibition.
Cortical morphogenesis in Paramecium aurelia following amputation of the anterior region
Authors: Chen‐Shan Lily
Published: June 2005

The most anterior approximately 35 μ of the 49–50 μ long anterior region was removed from many paramecia by a transverse cut. The challenge imposed by the amputation met with the following responses in lines of successive proters (anterior products of fission).

Restitution of the anterior region in successive proters. Most of the restitution occurred at the first fission which yielded proters having anterior region about 55% (as compared with the approximately 30% remaining after amputation) and posterior regions 68% of normal length. Return to normal was nearly complete after the eighth fission.

Incomplete kineties in successive proters. The anterior termini of incomplete kineties came to be located more and more posteriorly in the course of successive fissions as growth occurred anterior to them. When the anterior termini came to be posterior to the fission plane, they were lost from the proters formed at this and subsequent fissions. Proters with reduced kineties were slenderer than normal.

Dorsal kinety pattern in the proters. On the dorsal field, after all short kineties were lost from the proters, the remaining kineties were normally oriented anterior‐posteriorly. However, the normal arrangement of the anterior termini of kineties at the suture, on the dorsal anterior tip of the proters, was lacking.

Ventral kinety pattern in the regenerated anterior region. Regenerated anterior regions possessed normal or nearly normal ventral kinety patterns. Deviations from normal were minor.

The preoral suture. Normally this is a clear space at the juncture between the anterior ventral right and left field. The regenerated part of the suture was atypical: the clear space was lacking.

Inheritance and variation of total number of kineties around the cell. In a slender clone, the mean number of kineties was 67 as compared with 75 in an uncut control clone. The difference was inherited for many fissions, but not permanently. Normally, the number of kineties decreases slowly when fission rate is low due to limitation of food and rises slowly when excess food is supplied.

Abnormal buccal structures. Cuts made close to the vestibule, but not those further from the vestibule, resulted in death or in abnormal clones with defective buccal structures of various sorts.
The effects of pressure on cell division and oral morphogenesis in Tetrahymena
Authors: Simpson Robert E. , Williams Norman E.
Published: June 2005

The effects of brief exposures to high hydrostatic pressure on cell division and oral morphogenesis in synchronized Tetraphymena have been studied. The results indicate a “transition point” at approximately 45 minutes after the end of the synchronizing treatment. Prior to the transition point, pressure treatment produced long division delays and a correlated blockage or reversal of oral differentiation. Treatment with pressure after this time also blocked oral morphogenesis, but most cells continued to divide, and produced daughter cells with incomplete oral structures. After consideration of these data in relation to results with cycloheximide and colchicine, we suggest that the effects of pressure on protein‐protein interaction may be responsible, at least in part, for the consequences of pressure application prior to the transition point, and may be entirely responsible for the effects found after the transition point. Cell development after the transition point in Tetrahymena, therefore, may be exclusively dependent on assembly processes.
Active polysomes in sea urchin eggs and zygotes: Evidence for an increase in translatable messenger RNA after fertilization
Authors: Denny Paul C. , Reback Patricia
Published: June 2005

The increase in polysomal material in sea urchin zygotes after fertilization occurs primarily as an increase in the number rather than in the sizes of the polysomes. This suggests that the protein synthesis system in eggs is messenger RNA limited and that polysomes form at fertilization as a result of the messenger RNA becoming available. While these findings do not rule out the possibility that the peptide initiation step is less efficient in eggs than in embryos, they do suggest that this step is not the principal cause of the inactivity of the protein synthesis system in eggs.
Developmental potentialities of blastema cell nuclei of the Mexican Axolotl
Authors: Dasgupta Sanjoy
Published: June 2005

During amphibian limb regeneration, differentiated cells contribute to the formation of a blastema. Cells once incorporated into the blastema are identical in their morphological appearances. This investigation is a test of the developmental potentialities of blastema cell nuclei as revealed by means of nuclear transplantation.

When blastula cell nuclei are injected into enucleated eggs, approximately 80–90% of the test eggs cleave. Over half of the cleaved eggs form regular blastulae. Of the regular blastuae 60% form post‐neurula embryos.

The initial experiment with regenerating cells involved the ijection of two to three blastema cell nuclei from a seven‐day‐old regenerate into test eggs. The blastema cells were obtained from a white Axolotl (dd) and the test eggs were laid by a dark Axolotl (Dd). Of some 35 eggs injected, five partial and two regular blastulae were obtained. One of the regular blastulae was sacrificed after 24 hours of development, and part of its tissue was grafted on an embryo of the genetic composition DD. When the host started to develop its pigmentation, the graft developed as a white patch, thus indicating the genetic nature of the graft was that of transplanted blastema cell nucleus. Subsequently single blastema cell nuclei from seven‐ to sixteen‐day‐old regenerates were injected into test eggs. Blastema cell nuclei of eight‐day‐old regenerates were injected into test eggs. Blastema cell nuclei of eight‐day‐old regenerates were able to promote development of post neurula embryos.
Electrical correlates of neural superposition in the eye of the fly Sarcophaga bullata
Authors: Mote Michael I.
Published: June 2005

Responses to light at focal recording sites in the lamina ganglionaris of the fly Sarcophaga bullata were investigated as a function of geometrical parameters of the stimulus. The mean receptive angle of the laminar response was 12° at 50% response, or about twice the value observed in single retinular units of other species, but in some cases it approached the 6° values reported for single retinular cells. Illumination of areas on the surface of the eye with focused light indicated that sensitivity at the recording site was greatest to illumination of certain facets distributed asymmetrically within the area, and forming an oblong or elliptical pattern. Simultaneously illuminated pairs of facets did not provide strong evidence for lateral interaction. Results are discussed in light of predictions made on the basis of the neural superposition model of Kirschfeld, and it is concluded that the response recorded in the lamina is representative of activity expected from the optic cartridges located in that region.
Compatibility in insect tissue transplantations. I. Ovarian transplantations and hybrid formation between Drosophila species endemic to Hawaii
Authors: Kambysellis Michael P.
Published: June 2005

Interspecific larval ovarian transplantation between Drosophila species endemic to Hawaii revealed a remarkable uniformity of the internal environment among species of the picture‐winged group, in contrast to the high diversity observed for the mainland species. Various expressions of incompatibility were observed which were far less pronounced than in the case of the mainland species. The suitability of host environment for ovarian growth appears to be correlated with the rapid evolution of the group.

The potentiality for gene exchange between species highly diversified morphologically and normally not interbreeding confirms the significance of ethological isolation in preventing species hybridization and indicates the conservative diversity in the genetic architecture of the picture‐winged species.

The degree of chromosomal asynapsis observed in the hybrids between homosequential species could suggest the existence of differences in the fine structure of chromosomes. It further indicates the significance of point mutation in Hawaiian Drosophila speciation.
The ultrastructure of the compound eye of a mosquito Aedes aegypti L
Authors: Brammer J. D.
Published: June 2005

Each ommatidium in the mosquito compound eye consists of a dioptric apparatus and layer of retinula cells. The dioptric apparatus includes a cuticular cornea, a biconvex lens, and four cone cells. The cone cells have processes which extend into the receptor layer and terminate below the rhabdom as pigment‐filled sacs. Two primary pigment cells and an undetermined number of secondary pigment cells surround the dioptric apparatus. In the receptor layer eight retinula cells are found in each ommatidium. Six are peripherally arranged around a central one, whereas the remaining retinula cell is sandwiched between and somewhat external to two of the peripheral retinula cells. Each of the eight retinula cells possesses a well developed rhabdomere, along with the usual array of other intracellular organelles characteristic of arthropod photoreceptor cells.