bluuebunny/crossref_metadata_2025 huggingface dataset:
A survey of reduced silver techniques for demonstrating neuronal degeneration in insects
Authors: Lund R. D. , Collett T. S.
Published: June 2005

Degeneration reactions in locust and moth brains have been studied using a number of techniques commonly applied to the vertebrate nervous system after a variety of central and peripheral lesions. The degeneration reaction is stainable by Nauta rather than “neurofibrillar” methods. A survival time of 2–3 days is desirable to produce staining of the part of the axon separated from its cell body. Three techniques are reliable and generally consistent one with another: the methods of Nauta and Gygax ('51) and of Fink and Heimer ('67) after formaldehyde fixation on frozen sections or with modification on paraffin sections, and the method of Nauta and Gygax ('54), with or without some of the pretreatment stages omitted, on material fixed in formol‐dichromate solution.

Material stained by the last method and studied under the electron microscope shows stain granules in axons and terminals partly associated with dense bodies (possibly degenerating mitochondria) and partly more widely scattered.

The reliability of the methods has been tested by examining degeneration patterns after lesions in the optic lobe restricted to the retina, lamina and medulla. The resulting distribution of degeneration granules can in part be predicted with some confidence from the descriptions of Cajal and Sanchez ('15), and Zawarzin ('13).

It is hoped that the methods in association with fine structural correlative studies may be useful in elucidating anatomical interrelations within the insect nervous system.
Attempts to induce polyspermy in the rabbit by delayed insemination and treatment with progesterone
Authors: Chang M. C. , Hunt Dorothy M.
Published: June 2005

Rabbits were injected with progesterone at various times before ovulation and inseminated at the time of ovulation (delayed insemination). When their eggs were examined 11–13 hours after ovulation, it was found that 15, 63, 73, and 61% of the eggs were penetrated following the injection of 4 mg progesterone at 24, 12, 6, and 0 hours, respectively, before ovulation as against 51% for control animals. Of the 213 penetrated eggs, 84% had two pronounclei with two polar bodies, 9% had three pronuclei without the second polar body, 3% had three pronuclei with the second polar body, 3% were unevenly cleaved, and 1% had two fertilizing sperm tails. These abnormalities were not correlated with the time of progesterone treatment. The formation of one or two pronuclei was frequently observed when aged, unfertilized eggs were cultured for 3–4 hours. It was concluded that the presence of three pronuclei following delayed mating in the rabbit is due to the formation of a pronucleus from the second polar body or to the fragmentation of the female pronucleus, rather than to polyspermy.
The differentiation of crayfish muscle fibers during development
Authors: Bittner George D.
Published: June 2005

As the length (x, mm) of the propodite segment of a crayfish cheliped doubles, the average diameter of the opener muscle fibers also doubles, whereas average fiber length (y, mm) is given by y = 0.16 × + 0.5. Fiber length is increased by the continuous addition of new sarcomeres in propodites 6–22 mm long; in propodites of less than 6 mm, about half the linear growth can be accounted for by increases in sarcomere length. Cable properties of opener muscle fibers differ from those of vertebrate fibers. In a claw of any given size, length constant is not correlated with fiber diameter, muscle input resistance is not proportional to the two‐thirds power of the diameter, and mjp amplitude is independent of input resistance. Electrical properties of opener fibers change during growth, but the extent of the change is not predictable from classical cable equations.
Correlated physiological and ultrastructural studies on specialised muscles. Ib. Ultrastructure of white and pink fibers of the levator of the eyestalk of Podophthalmus vigil (Weber)
Authors: Hoyle Graham , McNeill Patricia Ann
Published: June 2005

The ultrastructure of the different kinds of muscle fiber found in the specialised eyestalk levator muscle of Podophthalmus vigil was determined by electron microscopy. Pink fibers have wide, 13 μ sarcomeres, an extensive cleft system, branching Z tubules and a thick layer of mitochondria. Their ratio of thin to thick filaments is 4–5:1. Two distinct kinds of white fiber were found, with sarcomere lengths of 7.9 μ and 9.8 μ. The former have a very well‐developed SR, few mitochondria, a thin: thick filament ratio of 3–5:1 and numerous diads. The second kind have a 7:1 ratio, the thin filaments not being in orbits around thick ones. Their SR is quite well developed, but the cleft system only moderately so. There are more mitochondria in them than in the other white fibers.
Reciprocal insemination and egg transfer between ferrets and mink
Authors: Chang M. C.
Published: June 2005

Epididymal mink sperm were injected into the uteri of 12 ferrets. On various days after insemination, 80 fertilized eggs and implantation sites including three living embryos in 11 ferrets were observed. No embryos, however, survived beyond 26 days. Ferret sperm were injected into the uteri or ovarian capsules of 22 mink; none of 165 eggs were fertilized. Ferret and mink eggs recovered at different times and from different parts of the genital tract were measured and recorded. When 77 ferret eggs were transferred into the uteri of nine mink, the majority of them developed at a slower rate than normal for a few days and then degenerated, but none implanted. Most of the 67 mink eggs transferred to the uteri of nine ferrets developed and implanted, but all degenerated after implantation. Fifty‐one ferret eggs were transferred to the uteri of eight ferrets; 13 living fetuses and four young were obtained. Eleven mink eggs were transferred into the uteri of two mink; only one implantation site was observed.

It is concluded that a high proportion of ferret eggs can be fertilized if a large number of mink sperm are injected, but mink eggs cannot be fertilized by ferret sperm. Ferret blastocysts can develop for a few days in the uterus of mink, but implantation fails. Although mink blastocysts can develop and implant in the uterus of ferrets, they degenerate after implantation.
Enzymatic estimation of glycogen in the cleaving mouse embryo
Authors: Stern Samuel , Biggers J. D.
Published: June 2005

Recently developed enzymatic techniques for the ultramicro determination of glycogen (Bueding and Hawkins, '64; Passonneau et al., '67) were used to estimate the glycogen content of preimplantation mouse embryos. From an initial value of 0.14 mμg glycogen/embryo in the 1‐cell fertilized egg. the amount of glycogen increased to 2.24 mμg/embryo at the 8‐cell stage. During the next 48 hours of development, the level fell to 1.81 mμg/embryo.

A comparison with previous histochemical findings (Thomson and Brinster, '66) and the possible relationship of glycogen concentration and metabolic capabilities of the embryos is discussed.
Selective affinity as a working force in neurulation movements
Authors: Jacobson Carl‐Olof
Published: June 2005

The appearance of selectivity in the mutual adhesiveness of cells in the vertebrate embryo has been mentioned previously as one of the forces which may be responsible for neurulation. We report here observations made in vivo and on sections of fixed amphibian larvae, on which lateral and medial parts of the neural plate (after transplantation) have been brought into contact with each other at various stages. Our results showed that selective affinities are not released until a stage when neurulation is almost completed. The role of adhesive selectivity and other forces in neural tube formation are discussed.
The development and effect of genetic background on expressivity and penetrance of the Brachyury mutation in the mouse: A study in developmental genetics
Authors: Wittman Karl S. , Hamburgh Max
Published: June 2005

The development of the posterior axial structure of the heterozygous Brachy (T/+) mutant was studied and the expressivity and penetrance of this gene on several genetic backgrounds was analyzed.

The Brachy mutant in heterozygous conditions is a dominant non‐lethal and interferes with the normal development of the caudal axis, leading to blunting, shortening and bending of the tail.

Study of the developmental changes encountered in T/+ mice from the sixteenth day of gestation until the tenth day of postnatal age revealed that three different processes contribute to the tail abnormalities, these are: (1) reduction in number of tail vertebrae, (2) fragmentation of vertebral processes, (3) fusion of vertebrae or vertebral fragments.

The expressivity and penetrance of the T gene in heterozygous condition was tested on four different genetic backgrounds provided by the Black Spot strain, the C57B1/6 strain, the DBA/2 strain and the Swiss Albino strain.

On the DBA/2 strain, the effect of the T gene on reduction of caudal vertebrae was considerably modified when the DBA background was provided by the female parent. In reciprocal crosses of ♀T/ × ♂DBA ±, the expression of the T gene on that aspect of development was not changed. The penetrance of the T gene was, however, changed to a 2:1 ratio instead of the expected 1:1 ratio in both reciprocal crosses between T/+ heterozygotes with DBA mice.

These results are interpreted as suggesting that the genetic background consists of several “factors,” each controlling independently the expression of some distinct aspect of the T gene, probably by stimulating some kind of correcting processes. The results are further interpreted to mean that some of the modifiers of T gene expressivity are probably non‐nuclear or cytoplasmic in origin, whereas the factors changing penentrance of the T gene are probably provided by more orthodox nuclear genetic loci that operate to inhibit its total activity.
Mitosis in normal and regenerating planarians
Authors: Best Jay Boyd , Hand Sharon , Rosenvold Robert
Published: June 2005

The rate of mitosis in planarians was measured by two methods. First, by tabulating the proportion of nuclei displaying metaphase mitotic figures after varying lengths of time in colchicine. Second, by measuring the total DNA in a colony of planarians as a function of time. The first method gave a rate of mitosis by non‐regenerating Dugesia dorotocephala of 1.4 × 10−4 divisions/cell hour. This rate remains constant for the first 24 hours following decapitation but increases to 2.7 × 10−4 divisions/cell hour by 54 hours. The rate of mitosis in the blastema was no larger than that of the mesenchymal tissues of the older portions. Measurements of the total DNA versus time gave an estimate of the average rate of cell division for spontaneously fissioning planarians of 5.8 × 10−4 divisions/cell hour which, in view of the tendency of the colchicine method to underestimate the true rate, is in satisfactory agreement. The implications of these results for mechanisms of regeneration are discussed.
An analysis of cytokinesis in cultured newt cells
Authors: Rappaport R. , Rappaport B. N.
Published: June 2005

Cells from the kidneys of the newt Diemictylus (Triturus) viridescens were cultured and used in experiments designed to yield information on cytokinesis. Observations and experiments were restricted to cells that were spread and flattened on the substratum. Flattened cells were capable of initiating and completing division without rounding up or disrupting their marginal attachments to the substratum. They can initiate division from a variety of geometric forms. At interphase and during division, flattened cells are under appreciable self‐induced tensile stress. Division continues when the cell is stretched between needles shortly after furrow establishment. Movement of needles between the cell and the substratum disturbed cells only when the tips of a marginal process were detached. No other connections between cell and substratum could be demonstrated. Objects stuck to the furrow surface and the stretching of attached marginal processes revealed that new surface in the furrow area is created by the stretching of pre‐existing surface. Massive cytoplasmic flow induced by micromanipulation immediately after the beginning of division and maintained throughout the process did not hamper furrowing. Division does not appear to depend upon any specific subsurface cytoplasmic arrangement in the equatorial plane and is unaffected by redistribution of the cytoplasm after the furrow is established.
The feeding biology of the gymnoblastic hydroid, Pennaria tiarella
Authors: Pardy Rosevelt L. , Lenhoff Howard M.
Published: June 2005

The role in food capture of the nematocysts on the filiform and capitate tentacles of Pennaria tiarella is discussed. The feeding response of Pennaria tiarella to Artemia extracts consists of cone bending and mouth opening. A similar feeding response has been demonstrated to be induced by proline at concentration as low as 10−6M. Pipecolic acid, a proline analog, also elicits a feeding response. Proline causes the head of the capitate tentacles to shrink, thereby causing the cnidocils of the large stenoteles to be prominent.
Evidence of circadian rhythms in a cave crayfish
Authors: Jegla Thomas C. , Poulson Thomas L.
Published: June 2005

Evidence of a circadiam clock mechanism was found in the cave crayfish, Orconectes pellucidus, even though it is blind and has been isolated from daily cycles for at least 25,000 generations. Five of seven crayfish tested under cave conditions of continuous darkness and 13°C showed apparent rhythms of activity and/or oxygen consumption. These rhythms were statistically significant, as judged by autocorrelation, for three individuals with average periods of 26, 27, and 34 hours. All three crayfish exposed to light:dark cycles with a 24 hour period showed more regular rhythmicity than in continuous darkness but only one showed clear evidence of entrainment, i.e., synchrony of activity or oxygen consumption with the light: dark cycle. Another crayfish tested apparently conformed to Aschoff's circadian rule.
In vitro studies on the mechanical evocation of adventitious cartilage in the chick
Authors: Hall B. K.
Published: June 2005

The quadratojugal‐quadrate articulation from 9–12 day chick embryos was cultivated in vitro and subjected to artificial mechanical stimulation by moving the quadratojugal against the quadrate. Under the influence of this artificial application of intermittent pressure and tension it was found that the germinal cells of the membrane bone were switched from osteogenesis to adventitious chondrogenesis. The quadratojugal‐jugal articulation was treated in a similar manner but no formation of cartilage was seen. Quadratojugal‐quadrate articulations were also cultivated between “rib‐cultures” under constant pressure and it was found that no switch to cartilage formation occurred. It was postulated that the adventitous cartilage which develops on the membrane bones of the embryonic chick arises in response to intermittent pressure and tension accompained by movement.
Patterns of soluble proteins and multiple forms of dehydrogenases in amphibian development
Authors: Chen P. S.
Published: June 2005

In the three amphibian species Bombina variegata, Rana temporaria and Triturus alpestris there is a two‐ to threefold increase in the total content of saline‐soluble proteins during development (prior to feeding). Analyses by polyacrylamide gel electrophoresis revealed the appearance of one or two new protein fractions at gastrulation. Protein bands of transitional occurrence were also observed at various developmental stages. In general, during early embryogenesis protein components with relatively low migrating rates in the anodal direction predominate, whereas in the late larvae fractions of higher mobilities are more abundant.

The isozymic patterns of four dehydrogenases in both embryonic and adult tissues of the three amphibians have been analysed. Three molecular forms of lactate dehydrogenase (LDH) are present in Bombina and Triturus, and two in Rana. Triturus and Rana have only a single malate dehydrogenase (MDH), whereas Bombina has two with, however, a clear difference in the mobility of the minor band between embryonic and adult stages. The total number of molecular forms of glucose‐6‐phosphate dehydrogenase (GDH) varies from four in Bombina to two in Rana and Triturus. There are probably four to five isozymes of alcohol dehydrogenase (ADH) of very low activity.

Morphogenetic changes of the isozymic patterns include the appearance of one MDH in Bombina and the gradual increases in activities of LDH, GDH and MDH in Rana at gastrulation. After hatching further appearance of ADH isozymes occurs. The new synthesis of one GDH in the late Bombina larvae seems largely associated with the differentiation of heart and fat body. The formation of one MDH in this amphibian is probably delayed until after metamorphosis. A shift in the relative synthesis of isozymes during Bombina development is indicated by the temporary loss of one LDH band at tail‐bud formation and after hatching.
Thyroxine induced tail resorption in vitro as affected by anterior pituitary hormones
Authors: Derby A. , Etkin W.
Published: June 2005

It has been previously shown that discs prepared from the tail fins of tadpoles, (R. pipiens), survive in vitro for several weeks and respond to thyroxine by undergoing resorption. Discs cut from animals during metamorphic climax, demonstrate rapid resorption without addition of exogenous thyroxine.

Discs were cut from tadpoles in early prometamorphosis and in climax and were implanted with either whole pituitary glands or the separate lobes. Controls were either implanted with cerebrum or sham‐operated. These discs were maintained in solutions of thyroxine in Hanks medium, (3 ppb or 6 ppb), or in control, Hanks medium. In addition, discs from animals in early prometamorphosis were injected with either prolactin, GH, or control medium and discs from animals at climax were immersed in solutions of prolactin, GH, FSH and control medium.

The results of these experiments demonstrates that the anterior pituitary, of the tadpole releases a factor that interferes with the action of thyroxine on tail discs in vitro. Prolactin and GH demonstrate similar activity but are less effective than the graft pituitaries. The results are interpreted to indicate that antagonism exists with respect to tail resorption between a pituitary growth factor, (possibly a prolactin‐like, or GH‐like molecule) and thyroid hormone.
RNA composition of the planarian, Dugesia dorotocephala
Authors: Stewart Kathleen , Goodman Alan B. , Best Jay B.
Published: June 2005

The RNA of anterior and posterior regions of normal and regenerating planarians was extracted by means of a modification of the phenol procedure, and further purified. The nucleotide composition of this RNA was determined by subjecting it to alkaline hydrolysis and resolving the constituent nucleotides by thin layer electrophoresis. Contrary to older reports there was no difference in either amount or base composition of the total RNA from anterior and posterior regions or between regenerate and control worms. Resolution of the various molecular weight species of the planarian RNA by sucrose density centrifugation and gel filtration revealed a typical distribution between ribosomal and transfer RNA as well as the explanation of the negative result. Constancy of base composition of the predominate ribosomal RNA would mask any anticipated changes in base composition.
Experiments and observations on the histology and mechanism of autotomy and regeneration in Gena varia (Prosobranchia, Trochidae)
Authors: Fishelson Lev , Kidron Guliette
Published: June 2005

This investigation describes the autotomy and regeneration of the metapodium in the mollusc, G. varia, a species inhabiting infratidal habitats along the Red Sea littoral. It was shown that in this species there is a histologically prominent autotomy line that separates the metapodium from the propodium and enables autotomy. The animals can regenerate the dropped‐off part of the foot and at new irritation, they can reautotomize and re‐regenerate new metapodia.

The histological development of the regenerate is described in detail, especially the development of the neural net and the musculature.
The influence of temperature on steroidogenesis in the rat testis
Authors: LeVier Robert R. , Spaziani Eugene
Published: June 2005

The normal temperature of the rat testis in a scrotal position is approximately 32°C. In vitro incubation of normal testicular tissue at various temperatures has demonstrated a 32°C optimum for the incorporation of lysine and glucose into protein. A thermal optimum of 32°C was also found for the conversion of cholesterol to components of both the Δ4‐ and Δ5‐ steroidogenic pathways except for pregnenolone synthesis which has a positive temperature co‐efficient between 28°C and 36°C. The Δ5‐pathway may be more sensitive than the Δ4‐pathway. In vivo inhibition of protein synthesis with cycloheximide simulated a temperature effect. Compared to saline injected control, tissue from inhibitor treated animals converted less cholesterol to steroids when incubated at 32°C, except for pregnenolone. In vitro cycloheximide treatment was less selective than inhibition of protein synthesis in vivo in that the synthesis of all steroid intermediates was suppressed below control levels. In addition, the hexose monophosphate shunt is less active at 36°C than at 32°C based on the in vitro yields of 14CO2 from glucose‐1‐14C and glucose‐6‐14C.

On the basic of these experiments, a hypothesis was proposed which can serve as a foundation for further study concerning the mode of action of temperature in regulating testicular function. The hypothesis is that a thermal environment above or below 32°C in the rat interferes with some aspect of protein synthesis, thus reducing the level of one or more enzyme related to the steroidogenic pathways beyond pregnenolone.
The developmental genetics of polymorphism in the rotiferAsplanchna. I. Dietary vitamin E control of mitosis and morphogenesis in embryos
Authors: Birky C. W.
Published: June 2005

Cultures ofAsplanchna sieboldifedParamecium aureliaconsist exclusively of parthenogenetically‐reproducing females whose body form is saccate. When such females are fed algae or α‐tocopherol, their offspring developin uterointo humped females with regular outgrowths of the syncytial body wall (hypodermis and cuticle). The hypodermal nuclei are constant in number and position, and can be mapped; such nuclear maps show that saccate and humped females have the same number and arrangement of hypodermal nuclei. The level of dietary vitamin E thus controls differential growth of the hypodermis, without affecting mitosis. Electron micrographs indicate that the hypodermal outgrowths are produced after cell membranes break down in the embryo; the regions of enhanced growth within the hypodermis are therefore not delimited by cell membranes. In contrast, the offspring ofA. sieboldiorA. brightwellifed vitamin E show an increased mean number of nuclei in the vitellarium and gastric glands, organs which are partially freed from the usual rigid control of nuclear number in rotifer tissues. Variations in nuclear number in a tissue might reflect variations in either the number of cells determined to form that tissue or the number of mitotic divisions in the determined primordium. In the former case, reciprocal variations in nuclear number should be found in another tissue. The vitellarium and oocytes are the sole derivatives of a single blastomere; however, counts of oocytes fail to show reciprocal variations. Dietary vitamin E therefore controls, directly or indirectly, the number of mitoses in the vitellarium, and presumably also in the gastric glands.
Maturation of the mouse oocyte in vitro. I. Sequence and timing of nuclear progression
Authors: Donahue Roger P.
Published: June 2005

Liberation of mouse follicular oocytes into a chemically defined Krebs‐Ringer salt solution with pyruvate is followed by resumption of meiosis and completion of the first maturation division. Examination of fixed whole mount preparations by light microscopy reveals that 90–95% of the germinal vesicles breakdown and proceed at least as far as metaphase I where about 5% arrest; the remainder go on to metaphase II.

Three stages of chromatin condensation from the dictyate (germinal vesicle) stage are seen, first with filament shortening forming a chromatin lattice‐work followed by condensation about the nuclear and nucleolar periphery and finally the appearance of discrete bivalents. Just prior to appearance of the spindle, the bivalents are circularly arranged and reach their maximum shortness. Spindle formation is followed by prometaphase I, metaphase I, anaphase I, telophase I with first polar body formation, the chromatin mass stage in which the chromatin assumes a half‐moon shape, prometaphase II and finally metaphase II, the stage at which oocytes arrest both in vitro and in vivo.

Examination at one‐two hour intervals reveals first meiotic spindle formation beginning after three hours of culture and metaphase I first appearing at 4 and one‐half hours. After nine hours of culture the majority of the oocytes are in metaphase I and anaphase I first appears at this time. There appears to be a six hour asynchrony in this division, some germinal vesicles requiring six hours to breakdown and the metaphase II stage accumulating between 11 and 17 hours of culture.
Polymorphic control of subunit synthesis for the enzyme lactate dehydrogenase in the newt, Triturus viridescens
Authors: Sherr Charles J.
Published: June 2005

The newt, Triturus viridescens, shows a polymorphism for the genes controlling the synthesis of the enzyme lactate dehydrogenase (LDH). Homozygotes have either of two electrophoretically fast migrating bands. In heterozygotes, the isozymes present in both homozygote classes appear along with three additional isozymes of intermediate mobilities. An additional slowly migrating isozyme is found in all animals. The relationship between the three phenotypic distributions of isozymes in the population is consistent with the predicted phenotypic frequencies made in accordance with the Hardy‐Weinberg Law. No difference in the Km for pyruvate reduction or the thermal denaturation characteristics was noted between homogenates containing different isozyme distributions. The electrophoretically fast moving isozymes in all homogenates are inactivated at a higher temperature than the slowly migrating isozyme. The evolutionary significance of polymorphism for alleles controlling isozyme synthesis is discussed.
Deletion‐transplantation experiments on embryos of Fundulus heteroclitus. I. The posterior embryonic shield
Authors: Brummett Anna Ruth
Published: June 2005

Experiments are described in which the differentiative capacity of the posterior embryonic shield of the teleost, Fundulus heteroclitus, was investigated by means of deletion‐transplantation techniques.

The posterior embryonic shield, removed from early gastrulae to immediate postgastrulae and grafted into the pericardial cavity of slightly older embryos, exhibits considerable growth and differentiates typical trunk and tail structures involving all germ layers.

The donor embryos, in general, develop normal heads to pectoral fin regions. They lack all trunk structures except for gut and some gut derivatives. They frequently differentiate a very small “tail” with unpaired somites. The “tail” sometimes flattens and forms fin rays.

Collateral experiments involving the deletion and grafting of various parts of the germ ring provide data in agreement with the conclusion that the posterior embryonic shield supplies the bulk of material for the formation of the trunk and tail in teleosts.

The experiments are discussed from the standpoint of their elucidation of gastrulation, trunk and tail formation, embryonic regulation of defects, and endoderm formation in teleosts.
Effect of the interstitial‐cell‐stimulating hormone on testicular enzymes during spermatogenesis
Authors: Hitzeman Sister Jean Walter
Published: June 2005

The activities of 17β‐hydroxysteroid dehydrogenase and of some NADPH‐generating enzymes in the fetal mouse testis during the formation of the accessory reproductive glands indicate that Leydig cells synthesize androgens before gonadotropins are secreted. In the neonatal testis the seminiferous tubules grow rapidly and the relative volume of the intertubular tissues decreases. At the same time the absolute activity of 17βSDH also decreases but there is no evident loss of enzyme activity as the primary spermatocytes begin meiotic prophase. High levels of NADPH‐generating malic enzyme activity coincide with the onset of meiosis and the development of the spermatids, although the activity of 17βSDH remains constant. Both glucose‐6‐phosphate and isocitrate dehydrogenases, which can be activated by gonadotropin, show strong activity prior to spermiogenesis.

Significantly increased activities of 17βSDH and the ME occur in 10‐day postpartum intact mice four hours after a single injection of 0.25 unit ICSH. Exogenous gonadotropin stimulates G6PDH and IDH activities during divisions of spermatogonia five days after birth. The pituitary‐Leydig cell axis is stabilized after the beginning of meiosis so exogenous ICSH has little effect on testicular enzymes during the remainder of the first wave of spermatogenesis. Dependence of Leydig cell activities on pituitary gonadotropin seems to occur during pachytene or the early stages of spermatid formation. Androgen synthesis in the murine testis may be associated with the NADPH‐generating ME and IDH as well as G6PDH which has been implicated in other steroidogenic tissues.
In vitro and in situ analyses of the inhibitory effect of Creeper tissues
Authors: Elmer William A.
Published: June 2005

The growth of White Leghorn tibiotarsi, measured as an increase in length, total protein and DNA content, is significantly lower when co‐cultured in the presence of 6.5‐7‐day Creeper tibiotarsi. The growth of White Leghorn tibiotarsi is not affected with increasing age of the Creeper donor. Quantitative measurements of in situ growth of Creeper and White Leghorn tibiotarsi were made for a comparison with the in vitro effect. Creeper rudiments do not accumulate protein as fast as White Leghorn rudiments. Creeper rudiments show a lag phase in DNA accumulation up to the eighth day and then accumulate DNA at the same rate as White Leghorn rudiments. The evidence suggests that Creeper is acting primarily on protein metabolism.
Morphogenesis of the eye lens in a mouse strain with hereditary cataracts
Authors: Zwaan Johan , Williams Randolph M.
Published: June 2005

Mice carrying the gene “Shrivelled, ” also known as “Cataract‐Fraser” or “Cataracta hereditaria subcapsularis, ” invariably develop lens opacities which are visible when the animals open their eyes on the fourteenth postnatal day.

Lens development in normal and mutant embryos is the same until day 14 of gestation. At this stage the nuclei of the lens fibers in the controls are large and vesicular with prominent nucleoli. In the mutants the centrally located nuclei are smaller and darker with indistinct nucleoli. The nuclei of normal fibers remain large and open even after birth; those in the mutants continue to undergo pyknosis after passing through the equatorial zone in the regular fashion. The nuclear degeneration is followed, with a delay of about 24–48 hours, by swelling and vacuolization of the fibers concerned. In the adult the lens core forms an amorphous eosinophilic mass or may partly be resorbed. The cortical fibers remain normal. Anterior polar cataracts develop: the epithelial cells proliferate to form multiple layers of atypical cells, surrounded by lens capsule‐like material.

The fiber degeneration may be caused by precocious cessation of protein synthesis after the cell nucleus becomes defunct. The late epithelial aberrations may be secondary to the changes in the underlying fibers and are possibly related to the reactivation of cell replication in the central part of lens epithelium seen after traum.
Budding in Hydra viridis
Authors: Shostak Stanley , Bisbee John W. , Ashkin Claire , Tammariello Robert V.
Published: June 2005

The rate of growth of a population of Hydra viridis by budding is shown to be a function of the frequency of bud‐initiations and not of the duration of bud development. Different rates of growth in populations were imposed by feeding the animals three, five, or seven days a week. The slowest growth rate was observed in animals fed Monday, Wednesday, and Friday, while those fed Monday through Wednesday grew at the same rate as hydra fed Monday through Friday. Not only was the duration of the bud development independent of the feeding schedules, but the duration of each of the stages of bud development was also unaltered despite differences in the frequency of feeding. This rigidity is not explained as a consequence of the distal end of the bud prescribing the course and rate of bud development; removal of the distal end, or replacing it with a distal end from a bud or animal at a different developmental and chronological age, had no effect on the development of the original bud's base or the time of its detachment. It seems that bud‐initiation depends on the parental production of a quantum of cells which can completely support the further development of a bud. Differences in the number of buds produced on any parent would thus be a function of the number of quanta produced.
Influence of estrogen and progesterone on the incorporation of 35S methionine by blastocysts in ovariectomized mice
Authors: Weitlauf Harry M. , Greenwald Gilbert S.
Published: June 2005

Incorporation of 35S methionine by mouse blastocysts in vivo, as detected by radioautography, provides a presumptive measure of the blastocysts' protein synthesizing activity. Normally, there is a marked increase in 35S methionine incorporation between 95 and 99 hours post coitum.

To determine whether or not ovarian hormones influence 35S methionine incorporation by the blastocysts, mice were ovariectomized on day 4 of pregnancy and injected with progesterone and/or estradiol 17‐β and given a single injection of 35S methionine. The results demonstrate that 35S methionine is incorporated in mouse blastocysts in vivo only after combined progesterone and estrogen treatment; 12 to 14 hours are required for the maximum response. Further, blastocysts were transferred (101–103 hours post coitum) from intact donors to ovariectomized, pseudopregnant recipients that were untreated or treated with progesterone or estradiol. The blastocysts incorporated 35S methionine, thus suggesting that hormonally induced changes in the blastocysts are responsible for initiating protein synthesis.

These findings provide a tentative explanation for the mechanism involved in initiating normal implantation and for terminating the embryonic diapause in the delayed implantation of lactation.
Effects of radiations on oral regeneration in Stentor coeruleus
Authors: Burchill Brower R.
Published: June 2005

Irradiation with ultraviolet light (254 nm) or ionizing radiation can prolong oral regeneration in the ciliate Stentor coeruleus. The primary response is an interruption in the regeneration cycle, starting soon after irradiation and leading to a delay in the completion of development. The relation of dose to delay, of cells irradiated early in regeneration, is approximately linear. Early stages of regeneration are maximally sensitive, with the peak sensitivity to ultraviolet light occurring slightly earlier than that to ionizing radiation. Cells irradiated with combined doses of both radiations are more affected than cells exposed to either single radiation dose alone. Possible interpretations of the results are discussed.
Hormonal and nutritional requirements for limb regeneration and survival of adult newts
Authors: Tassava Roy A.
Published: June 2005

Newts which were fed daily for two weeks prior to hypophysectomy survived significantly longer and regenerated limbs better than newts fasted for two weeks prior to hypophysectomy. Since limbs were amputated five days after hypophysectomy, regeneration was initiated in the complete absence of pituitary hormones.

Newts which were hypophysectomized 14 days after limb amputation were found to possess blastemas significantly smaller at eight and also at 16 days after the operation than the blastemas of sham‐operated newts. Thus, hypophysectomy, performed after limb regeneration had progressed through the wound healing and dedifferentiation phases, resulted in a significant retardation in the growth of the blastema.

To determine which hormones are essential to normal limb regeneration and survival, newts were hypophysectomized and treated with various combinations of hormones, or grafted with pituitaries from newts or from axolotls (Ambystoma mexicanum). A prolactin‐thyroxine combination, growth hormone, and ectopic pituitary grafts from newts or axolotls, significantly prolonged the life of hypophysectomized newts. These newts also regenerated limbs in a normal fashion. Thyroxine alone, prolactin alone, thyroxine + ACTH, ACTH, or saline were not effective in restoring the health of hypophysectomized newts and were not effective in restoring normal limb regeneration ability.
Protein changes during maturation of the free‐living nematode, Panagrellus silusiae
Authors: Chow H. Hu , Pasternak J.
Published: June 2005

The free‐living nematode Panagrellus silusiae can be grown synchronously through the postpartum period of its life cycle. This period is divided into four phases which in sequence are called the L2, L3, L4 and adult stages. Homogenates from each stage were analyzed electrophoretically in order to discover whether protein changes occur during postembryonic development. Protein patterns in acrylamide gels from L2, L3, L4 and adult stages show no differences in the number of bands (16), although there are differences in the intensity of certain bands at various stages.

Definite stage specific patterns were observed when enzyme activity was assayed histochemically. L4 larvae show five sites of lactate dehydrogenase activity in polyacrylamide gel; three of these are found in each of the other stages. L3 larval extracts have five sites of malate dehydrogenase activity; L2 larvae and adults share one of these and L4 larvae have two in common. L4 and adult nematodes each have one MDH type not present in any other stage. L4 larvae produce six sites of α‐naphthyl acetate esterase activity; four of these bands are present in each of the other stages. Both acid and alkaline phosphatase occur as single molecular forms in each postpartum stage.

It is concluded that during maturation a precise regulatory program operates to control the sequential appearance of specific enzymatic proteins.
New information from experimental crosses on genetic relationships within the Rana pipiens species group
Authors: Mecham John S.
Published: June 2005

Diploid crosses among Rana palustris, R. areolata, R. megapoda, R. montezumae, and three different forms of the Rana pipiens complex demonstrated a high level of genetic compatibility for most combinations. The results support inclusion of R. montezumae within the R. pipiens species group, and suggest a particularly close relationship between R. montezumae and R. megapoda. The only crosses to indicate pronounced incompatibility involved R. p. berlandieri. Crosses between Texas R. p. berlandieri and R. areolata, R. megapoda, and R. montezumae produced lethal syndromes of embryonic abnormalities. The other forms of R. pipiens that occur in Texas, R. p. sphenocephala and the southern plains type, proved to be highly compatible with these same species. Although all R. palustris X R. pipiens crosses produced normal larvae, embryonic defects were most pronounced with R. p. berlandieri. Rana p. spenocephala X southern plains and R. p. spenocephala X R. p. berlandieri combinations are at least moderately compatible. Striking defects appeared in southern plains ♀ X R. p. berlandieri ♂ crosses, however, although development proceeded to larva in crosses between allopatric populations, and hybrid males were fertile. Rana p. berlandieri appears to be highly incompatible with northern R. p. pipiens. The evidence from crossing experiments indicates that R. pipiens berlandieri has a highly distinctive genome, and strongly supports the separation of this from from R. pipiens as a distinct species. Developmental incompatibility in crosses within the R. pipiens species group and within the R. pipiens complex may be influenced by differences in temperature adaptation, but other factors are clearly involved.
Cortical morphogenesis in Paramecium aurelia following amputation of the posterior region
Authors: Chen‐Shan Lily
Published: June 2005

The present paper reports the results and consequences of transverse cuts made between vestibule and cytoproct of Paramecium aurelia. The structural developments of the cortex were observed by the silver impregnation method in successive opisthes (posterior products of fission).

Restitution of the posterior region in successive opisthes. Restitution was associated with the process of fission, most of it occurring at the first fission which yielded opisthes having anterior regions 90% of normal length and posterior regions 70% (as compared with the 30% remaining after amputation). Return to normal was nearly complete during the second fission; after the third fission there was no significant difference from normal.

Incomplete kineties, i.e., kineties that fail to extend to regions where normal kineties do. Incomplete kineties were found in successive opisthes of cut cells. Growth of complete kineties at latitudes posterior to the termini of incomplete kineties shifted these termini more and more anterior at successive fissions. Eventually the posterior terminations of the incomplete kineties fell anterior to the fission plane, removing them from the opisthe formed at this and subsequent fissions.

The kinety patterns in the regenerated posterior region, i.e., the spacing and the angular arrangement of the kineties on the two sides of the cytoproct line. In some opisthes the kinety patterns were similar to but not exactly the same as those of normal cells; in others. The kinety pattern on one side or both sides of the cytoproct line was distinctly abnormal.

Regeneration of the cytoproct. The cytoproct line reappeared within two hours after the first fission of three‐quarters of the opisthes; by the end of the second fission, it was present in almost all opisthes. The cytoproct regenerated in cells with abnormal kinety patterns as well as in those with normal kinety patterns.
Respiratory ammonia filtration, mucous composition and ammonia tolerance in bats
Authors: Studier Eugene H.
Published: June 2005

Maximum efficiency of removal of inhaled ammonia by respiratory mucous in three species of mammals has been determined by noting the increase above normal in plasma ammonia and urea nitrogen after exposing the blood in vivo and in vitro hightly ammoniated air. Guano bats, Tadarida brasiliensis, filtered 97.1% of the ammonia present in an inhaled mixture of 1130 PPM (parts per million ammonia). These bats further filtered 73.4% of a 4420 PPM in air mixture, 72.6% at 5040 PPM and 53.9% and 7200 PPM. For little brown bats, Myotis lucifugus, filtering efficiencies of 84.5% at 1330 PPM and 77.5% at 3010 PPM were found. Mice, Mus musculus, were found to filter 76.9% at 870 PPM. Efficiency of respiratory ammonia filtration relates directly to tolerance to inhaled ammonia in these mammals.

Sodium, potassium, chloride, carbon dioxide, ammonia and urea nitrogen and protein levels in perfused respiratory tract fluid of the same three species after inhalation of ammonia in air mixtures are reported. In each species, ammonia and urea nitrogen levels in perfused respiratory tract fluid increases as inhaled concentrations of ammonia increase. In guano bats and little brown bats, carbon dioxide levels paralleled increases in ammonia apparently in sufficient quantity to provide the increase in buffering capacity necessary to neutralize absorbed ammonia. In mice, however, carbon dioxide levels dropped as inhaled ammonia levels increased. In no case did electrolyte or protein content change in any way to increase buffering capacity of respiratory mucous except in guano bats where protein levels rise consistently with inhaled ammonia concentrations.
Activation of ribosomal RNA synthesis in initiation of Wolffian lens regeneration
Authors: Reese David H. , Puccia Egidio , Yamada Tuneo
Published: June 2005

Tissue engaged in the transformation of iris into lens, triggered by lens removal in the adult newt (Triturus viridescens), was labeled in vitro with 14C‐uridine, and the sedimentation profiles of RNA synthesized by the tissue were studied in sucrose density gradients. The radioactivity in the 18S and 28S areas, which is insignificant in the normal iris, increases significantly during 2 to 10 days after lens removal, and subsequently retains a high level until the completion of lens regeneration. These data are interpreted as indicating activation of ribosomal RNA (rRNA) synthesis by lens removal, and are discussed in connection with the ultrastructural modification of the nucleoli. Further data from the radioactive profiles are consistent with the notion that the level of control of rRNA production in this system is the transcription of the rRNA precursor rather than the post‐transcriptional processing of the precursor. The activation of rRNA production described in this paper is the earliest event so far detected in this system, preceding activation of DNA replication, cell replication, and dedifferentiation.
The function of the accessory sex glands in Periplaneta americana (L.). II. The role of the juvenile hormone in the synthesis of protein and protocatechuic acid glucoside
Authors: Shaaya Eli , Bodenstein Dietrich
Published: June 2005

The left colleterial gland, as part of the accessory sex glands of the adult female cockroach, produces a structural protein and the phenolic tanning agent, protocatechuic acid glucoside. Both are needed for the formation of the egg capsule (ootheca), which contains the eggs of the species. The synthesis of the two compounds is under the control of the corpus allatum hormone. Transplanted colleterial glands are able to synthesize protein and glucoside in adult females; in adult males, however, the transplanted glands are able to synthesize only protein. They do not synthesize glucoside, even under the influence of additional juvenile hormone supplied to the male hosts by injection. Yet males produce enough juvenile hormone to promote the synthesis of protein and glucoside by colleterial gland cultured in female hosts. This was demonstrated by combining in parabiotic fusion adult males with decapitated adult females. The adult female apparently contains a factor which in the presence of juvenile hormone is a prerequisite for glucoside but not for protein synthesis. This factor is apparently also absent in nymphs of both sexes. The dependence of protein synthesis on the juvenile hormone provides a quantitative bioassay for estimating the juvenile hormone titer in all postembryonic stages of development. At present, glucoside synthesis can only be used as an indicator for the juvenile hormone concentration of adult females of different ages. The juvenile hormone presumably acts directly on the tissues of the collecterial glands.

This paper is dedicated to the memory of Professor Alfred Kühn, one of the great biologists of his time, who died in Tübingen, Germany on November 22, 1968.