bluuebunny/crossref_metadata_2025 huggingface dataset:
Viable amphibian hybrids produced by circumventing a block to cross‐fertilization (Rana clamitans ♀ × Rana catesbeiana ♂)
Authors: Elinson Richard P.
Published: June 2005

Eggs of Rana clamitans in their own jelly coat are not fertilized by sperm of other species. When the eggs were surrounded by jelly from another species, they were fertilized by R. catesbeiana and R. septentrionalis sperm. The hybrid nature of the resulting embryos was confirmed by detection of paternal enzyme forms. The R. clamitans ♀ × R. septentrionalis ♂ embryos arrested by the tailbud stage. The R. clamitans ♀ × R. catesbeiana ♂ embryos developed into viable tadpoles and subsequently metamorphosed. The hybridization results coupled with the similarity of enzyme patterns indicate that R. clamitans and R. catesbeiana are genetically closely related. R. clamitans is probably not as closely related to R. septentrionalis based on the enzyme patterns. Since cross‐fertilization or early developmental failures of hybrids could be explained by a small number of genes, such failures must be considered with caution in determining species relationships.
An analysis of color change phenomena in the leaf frog, Agalychnis dacnicolor
Authors: Iga Tetsuro , Bagnara Joseph T.
Published: June 2005

In vivo and in vitro studies of integumental color change in the leaf frog, Agalychnis dacnicolor, are reported. A color index is established for the assessment of color change in the absence of melanophore visibility. Green leaf frogs adapt rapidly to background by controlling MSH release. Some members of the population are always brown regardless of background. Naturally brown specimens respond to localized reductions in illumination by becoming green in the affected area. Either skin or chromatophores in these areas are photosensitive. Isolated skins darkened with theophylline are not photosensitive; however, masking of areas of isolated skins prevented darkening of the masked area. Contact between skin and mask may inhibit darkening by physically preventing melanosome dispersion. Neither melanosome aggregation nor dispersion occur in isolated skins incubated in oxygen‐free media. Experiments involving denervation and electrical stimulation both in vivo and in vitro fail to implicate a chromatophore control by innervation.
Prolactin‐thyroxine antagonism and the metamorphosis of visual pigments in Rana catesbeiana tadpoles
Authors: Crim Joe William
Published: June 2005

The relationship between prolactin‐thyroxine antagonism and the metamorphosis of visual pigments in larval amphibians has been investigated using bullfrog (Rana catesbeiana) tadpoles. Although prolactin‐thyroxine antagonism is demonstrable by morphological criteria, ovine prolactin does not appear to antagonize thyroxine‐induced rhodopsin synthesis. The hypothesis is offered that prolactin‐thyroxine antagonism is the result of differential gene activities which are opposite in their physiological effects.
Regeneration of the tail bud in Xenopus embryos
Authors: Deuchar Elizabeth M.
Published: June 2005

In an attempt to solve some aspects of the long‐standing controversy about the regenerative ability of appendages in vertebrate embryos, the tail bud of Xenopus laevis embryos has been amputated at stages ranging from St. 26 to St. 32 and its ability to regenerate during a culture period of 2–3 days has been studied. At amputation stages 26–28, the tail bud consisted only of undifferentiated mesoderm and ectoderm, but at stage 32 it had a fully differentiated neural tube, a vacuolated notochord and segmented somites. A total of 137 amputations at different stages gave consistent results: a tail formed in all the operated larvae and it had normal, well‐developed axial tissues in most cases. The relatively few cases with abnormal tail structure were stunted, oedematous larvae with defects in the trunk region as well. It is concluded from these experiments that cells near the original tail bud are able to differentiate into tailbud tissue and to replace the amputated region, even at these late embryonic stages. The implications of these findings for comparative studies on regeneration in vertebrates are discussed.
Gallium‐67 distribution in pregnant mammals
Authors: Tyndall R. L. , Chaskes S. J. , Carlton J. E. , Nelson Bill , Daniel J. C.
Published: June 2005

Studies on the distribution of 67Ga in pregnant rabbits showed a marked concentration of the isotope in uterine tissue and flushings of 5‐day pregnant rabbits 24 hours after isotope injection. The isotope no longer localized throughout the uterine tissues and flushings on injection of 7‐ to 8‐day pregnant rabbits but was specifically associated with the blastocysts and sites of implantation. As the gestation time progressed 67Ga increasingly concentrated in placental and mammary tissue while the concentration in serum and thymus tissue decreased. The marked concentration in placental tissue was readily discernible on total‐body scans of pregnant rabbits.

Column chromatography of uterine washings and placental extracts from pregnant rabbits and thymus extracts from estrous rabbits showed most of the isotope associated with moieties ⩾ 200,000 MW whereas the isotope in “milk” and extracts of mammary tissue was bound to components of 25,000–35,000 MW. Extracts of thymus from pregnant rats showed a marked, selective loss of 67Ga binding in two peaks of approximately 50,000 and 120,000 MW compared to the chromatographic profile of extracts from normal rat thymus.
Control of sex differences in the plumage of the house sparrow, Passer domesticus
Authors: Mueller Nancy S.
Published: June 2005

In an experimental study of sexual dimorphism in plumage coloration in the house sparrow, Passer domesticus, skin grafts were exchanged between nestlings on the first to sixth day after hatching. Before fledging, the young birds were moved from the nest to cages and kept for several weeks for observation of the coloration of feathers produced by host and graft skin. The adult feathers that developed on grafted skin at the postjuvenal molt corresponded to those of the donor, regardless of the sex of the host.
Evidence against gene expression after meiosis in the male mouse
Authors: Brock William A.
Published: June 2005

Isozyme patterns in homogenates from various testicular cell types from mice were examined in an effort to ascertain whether the haploid genome is expressed during spermiogenesis. Male mice heterozygous for electrophoretic variants of several glycolytic enzymes were analyzed by starch gel electrophoresis. The enzymes examined were isocitrate dehydrogenase, glucose‐6‐phosphate dehydrogenase, and glucosephosphate isomerase. The isozyme patterns produced by these dimeric enzymes reflect the relative activity of genes in each cell type. These patterns reveal the presence or absence of the transcription of specific genes during spermiogenesis. We found that the genes encoding these enzymes continue to increase during spermiogenesis. Synthesis of these enzymes most likely continues in spermatids, but this synthesis must depend upon premeiotically produced mRNA. These data provide biochemical evidence for the hypothesis that the phenotype of the haploid mammalian gamete depends upon the preceding diploid genome and that a mechanism must exist for the long term post‐transcriptional regulation of gene expression during spermiogenesis.
Termination of photorefractoriness in golden hamsters—photoperiodic requirements
Authors: Stetson Milton H. , Watson‐Whitmyre Marcia , Matt Kathleen S.
Published: June 2005

The photorefractory period of golden hamsters is characterized by the failure of short daylengths (<12.5 hours per 24) to induce gonadal regression. Photorefractoriness is terminated by prolonged exposure to long daylengths (>12.5 hours per 24). This study was designed to determine the precise duration of long day (LD 14:10; 14 hours light/24) exposure necessary to terminate refractoriness. The data indicate that 11 weeks of LD 14:10 terminate refractoriness in nearly every hamster. Exposure for fewer than 11 weeks is less effective whereas exposure for more than 11 weeks is no more effective. The data show that hamsters begin measuring long days to terminate photorefractoriness irrespective of the physiological state of the reproductive system, and, therefore, that photorefractoriness is induced some time during the period of testicular regression (during the first 10‐12 weeks of short day exposure).
Frog lysozyme. V. Isolation and some physical and immunochemical properties of lysozyme isozymes of the leopard frog, Rana pipiens
Authors: Snyder John A. , Harrison James H.
Published: June 2005

Frog Lysozyme has been purified by sequential application of acid extraction, salt fractionation, CM‐cellulose chromatography, heat treatment, and gel filtration. Eight isozymes of purified lysozyme were found to be stable during prolonged storage. Isozymes were separated by preparative polyacrylamide gel electrophoresis. Ninety percent of the lytic activity of frog ovarian egg was represented by forms 7 and 8, the most highly charged isozymes. Seventy‐eight percent of frog liver lysozyme activity was that of form 4. Forms 7 and 8 differed from form 4 by being larger (apparent molecular weight of 18,000 vs. 16,000), by remaining active in more acidic environment, and by exhibiting a dependency upon NaCl for activity. Antiserum prepared against frog form 4 did not react with frog forms 7 and 8 and antiserum to chicken egg‐white lysozyme did not react with any frog lysozymes. All frog lysozymes showed identical reversible binding to deaminated chitin. Apparent size differences and lack of immunological cross‐reactivity suggest that at least some of the isozymes are nonallelic.
The adjustable “pinhole camera” eye of Nautilus
Authors: Hurley Ann C. , Lange G. David , Hartline Peter H.
Published: June 2005

The “pinhole camera” eye of the chambered nautilus, Nautilus pompilius, contains an adjustable pupil which dilates or constricts in response to changes in light intensity. The dynamics of this pupillary reflex were studied. Closing times for the pupil in response to a sudden increase in light intensity were on the order of ninety seconds. Opening times in response to decreased light intensity were approximately fifty seconds. Stimulation of one eye would cause a constriction of the pupil in the unstimulated eye. The time course of this response was different from that seen in the ipsilateral stimulation experiments.
Water economy of the earthworm Lumbricus terrestris L.: Coping with the terrestrial environment
Authors: Carley Wayne W.
Published: June 2005

Although it displays many characteristics of a freshwater ani‐mal, the earthworm Lumbricus terrestris survives well in moist terrestrial environments. Earthworms in soil are only partially hydrated and gain weight when transferred to pond water. Worms in air of 70–80% relative humidity (RH) have a much higher dehydration rate than do animals at 100% RH. Compared with animals at 100% RH, the integumental water exchange rate of worms at 70–80% RH is significantly lower than expected based on the amount of water in the atmosphere. Lumbricus may reduce its integumental permeability to re‐strict water loss in terrestrial environments, but cannot regulate the osmotic pressure of its coelomic fluid at relative humidities lower than 100%.
Allopurinol‐induced melanism in the tiger salamander (Ambystoma tigrinum nebulosum)
Authors: Frost Sally K. , Bagnara Joseph T.
Published: June 2005

The enzyme, xanthine dehydrogenase (XDH), has been examined in Ambystoma tigrinum nebulosum with respect to its role in pigmentation. It now seems probable that the melanoid gene (m) either codes directly for XDH or is somehow intimately connected with the normal function of this enzyme. Inhibition of XDH using the drug, allopurinol, results in animals which appear to be phenocopies of melanoid mutants as described for the Mexican axolotl (Ambystoma mexicanum). The effects of allopurinol in terms of specific pigmentary alterations were examined, and a new method for analyzing heterogeneous extracts of skin pigments (e.g., purines and pteridines) is presented. The significance of the link between XDH and melanism is discussed with emphasis on possible mechanisms of pigment induction and general applicability to biological systems.
Parameters for growth of the imaginal wing disk in last instar larvae of Galleria mellonella L
Authors: Meyer Dietrich R. , Sachs Felix N. , Rohner Renate M.
Published: June 2005

In last instar larvae of Galleria mellonella, the observed increase in the number of cells of growing intact imaginal wing disks was completely blocked by ligation of the mesothorax and stimulated again by external applications of low and high doses (2.6 to 130 μg/g) of ecdysterone. However, at no hormonal dose applied has the full extent of normal wing growth been attained. The ecdysteroid dependent cuticle synthesis could be induced in disks of various sizes. The cell number of imaginal disks of young last or supernumerary instar larvae is exponentially correlated with the body weight. The rates of cell division during prepupal development of the wing disk appeared to be about the same in last and supernumerary instar larvae.

In normal pupae the borders of the everted wings are fitted precisely to a cuticular demarcation line on the underlying abdomen. X‐ray irradiations of last instar larvae led to a reduction of the pupal wing surface and cell number, but did not affect the position of the demarcation line. The X‐ray experiments confirm the finding that reduced wings are capable of normal pupal cuticle synthesis.
Dissolution of cytoplasmic actin bundles and the induction of nuclear actin bundles by dimethyl sulfoxide
Authors: Sanger J. W. , Gwinn J. , Sanger J. M.
Published: June 2005

Within 30 minutes of exposure to medium containing 10% dimethyl sulfoxide, PtK2 cells begin to round up and lose their cytoplasmic actin bundles. At the same time, bundles of actin filaments appear in the nuclei of the cells. One to 2 hours after the dimethyl sulfoxide is removed from the medium, the cells revert to their flattened shape, losing the nuclear actin bundles and regaining the cytoplasmic bundles.
Micronuclear events during conjugation in nucleo‐cytoplasmic hybrids of Paramecium caudatum
Authors: Fujishima Masahiro
Published: June 2005

The germinal micronucleus in cells of mating type V of P. caudatum, syngen 3 was removed and replaced with a micronucleus of syngen 1 by the microinjection method. The resulting nucleo‐cytoplasmic hybrids were able to grow with mitosis of the transplanted micronucleus. When these cells were mated with cells of complementary mating type VI, the micronucleus was able to perform all the prezygotic nuclear divisions normally occurring in conjugating syngen 3 cells. This technique of intersyngenic micronuclear transplantation may provide a good instrument for genetic analysis between different syngens in cases where conventional cross‐breeding analysis is not easy because of sexual isolation.
Immunochemical characterization and quantification of larval brine shrimp malate dehydrogenase
Authors: Hand S. C. , Conte F. P.
Published: June 2005

The cytosolic malate dehydrogenase (s‐MDH) from larval brine shrimp has been immunochemically characterized by quantitative rocket immunoelectrophoresis (IEP) and antibody catalytic inhibition studies. Monospecific rabbit antiserum produced against purified naupliar s‐MDH was used for rocket IEP as a quantitative assay for the cytoplasmic isozyme. Since cross‐reactivity was not observed against the mitochondrial MDH (m‐MDH), the assay allows specific measurement of the s‐MDH in crude naupliar supernatants in the presence of contaminating m‐MDH. The assay has a sensitivity of approximately 100 nanograms s‐MDH protein using either purified enzyme solutions or crude supernatant preparations. Catalytic inhibition studies using the monospecific antiserum gave 85% inhibition of s‐MDH but did not give significant inhibition of the m‐MDH. Lack of complete s‐MDH inhibition by the antiserum suggests a difference between the enzyme active site and immunological binding site. Although the antiserum was produced against s‐MDH from nauplii of the San Francisco Bay population, the antiserum inhibits equally well the s‐MDH of Great Salt Lake (Utah) nauplii, indicating little if any structural difference in the immunological sites of the s‐MDHs from these two geographical sources. Porcine (s‐ and m‐MDH), bovine (m‐MDH), and pigeon (m‐MDH) were also tried as antigens against the brine shrimp s‐MDH antiserum, but antigen‐antibody reactivity was not observed during rocket IEP or catalytic inhibition experiments.
Larval brine shrimp malate dehydrogenase: Biosynthesis and temporal pattern related to environmental salinity
Authors: Hand S. C. , Conte F. P.
Published: June 2005

Brine shrimp nauplii challenged with artificial sea water containing 2.5 M NaCl maintain significantly higher levels of cytoplasmic malate dehydrogenase (s‐MDH) than larvae incubated in sea water having 0.5 M NaCl. Eight to ten hours after emergence, free‐swimming nauplii living in 0.5 M NaCl exhibit a steady decline of s‐MDH for 20–40 hours; the decrease is less and stabilizes earlier — in nauplii incubated in 2.5 M NaCl. The 14C‐labeled amino acids produced by H 14CO3 fixation were rapidly incorporated into newly formed s‐MDH protein as assayed using quantitative rocket immunoelectrophoresis (IEP) with monospecific antiserum prepared against purified brine shrimp s‐MDH. Higher rates of enzyme biosynthesis (>45%) occurred in 2.5 M NaCl together with rapid s‐MDH turnover (half‐life = 17 hours), accounting for the difference observed in enzyme level between different salt regimes. In contrast, incorporation of 14C‐labeled amino acids into total cytoplasmic protein decreases slightly in high salt, suggesting that a preferential synthesis of s‐MDH is taking place. Temporal patterns of s‐MDH during embryonic development were monitored using both catalytic activity and quantitative IEP assays. Levels of s‐MDH seen in encysted gastrulae (0.22 units or 0.57μg s‐MDH protein/100 embryos) remain relatively constant through the E1 and E2 emergent stages until the exhibited decline observed in the naupliar stage. The results are discussed in relation to the bioenergetics and temporal development of water and electrolyte regulation in nauplii.
The culturing of dissociated newt forelimb regenerate cells
Authors: Jabaily Joseph A. , Blue Patricia , Singer Marcus
Published: June 2005

A procedure is described for the mechanical dissociation and culturing of early stage newt regenerate blastema cells. The specified growth medium is adjusted to suitable osmolarity and consists of Leibovitz L‐15, water, fetal calf serum, and insulin. This provides a suitable environment in which growth, proliferation, and some differentiation occur with time as evidenced by phase contrast photographs of living cultures.
Properties of the vitelline coat lysin from toad sperm
Authors: Iwao Yasuhiro , Katagiri Chiaki
Published: June 2005

The sperm of the toad, Bufo bufo japonicus, smeared on a gelatin film displays a “halo” reaction around the acrosomal region. The treatment of sperm with 0.5% Triton X‐100 yielded activity which lyses the vitelline coat (VC) of coelomic eggs, but not the fertilization coat of activated eggs. Electronmicroscopy showed that these detergent‐treated sperm had lost the plasma membrane and the acrosomal cap, indicating acrosomal localization of the VC lysin. The VC lysin was able to lyse the VCs of several heterologous anuran species, and this activity correlated well with the occurrence of cross‐fertilization by Bufo sperm. Proteolytic activities of the VC lysin were quantitated employing N,N‐dimethylated VC proteins or casein as substrates. Successive fractionation by NH4 2SO4 precipitation, DEAE‐cellulose chromatography, and Sephadex gel filtration yielded a 100‐fold increase of proteolytic activity compared with that of the original detergent extract. On gel filtration, the VC lysin activity was recovered both in the M.W. 54,000 fractions and the considerably higher (>100,000) M. W. fractions. Part of the latter activity was recoverable in the former after the treatment with urea and rechromatography. The VC lysin was most active at pH 7.4, but its activity was lost by preincubation at temperatures higher than 60°C. The activity was inhibited considerably by serine‐protease and chymotrypsin inhibitors, but not at all by trypsin inhibitors. The lysin was unable to hydrolyze arginine or tyrosine esters, but was able to hydrolyze active site titrants for chymotrypsin more effectively than for trypsin. In all aspects the VC lysin, although sharing some properties with serine‐proteases such as chymotrypsin, is a unique proteinase(s) well adapted to its role in fertilization.
Evidence for a stimulating effect of prolactin on teleostean hatching enzyme secretion
Authors: Schoots André F. M. , de Bont Rob G. , Van Eys Guillaume J. J. M. , Denucé J. Manuel
Published: June 2005

Homogenates of whole medakas and of trout prolactin lobes contain a factor that stimulates hatching enzyme secretion from medaka hatching gland explants. The elution volume in gel filtration indicates that the stimulating factor is a protein with a molecular weight of 19,000–20,000. Both its localization in the prolactin lobe and its apparent molecular weight suggest that this factor is prolactin. This is confirmed by an electrophoretic analysis of the biomajor products of the prolactin lobe, which demonstrates that prolactin is the major product found in the molecular mass range from 15,000 to 30,000 daltons. Since it is known that the pituitary gland of teleostean embryos has functional prolactin cells and that prolactin is an activator of integumentary glandular cells, we conclude that prolactin might be the primary stimulus in the activation of hatching gland cells leading to hatching enzyme secretion.
Immunological factors in Peromyscus speciation
Authors: Dawson Wallace D. , Reuning Sara C. , Finlay Mary‐F.
Published: June 2005

Reciprocal interspecific F1 hybrids of deermice (Peromyscus maniculatus) and oldfield mice (P. polionotus) differ significantly and substantially in fetal and placental, as well as adult, size and weight. Hybrid fetal mortality is associated with large conceptus size. Skin grafts were exchanged between and within the two species to ascertain whether any relationship exists between mean graft retention time and body size of fetuses and adults. P. maniculatus skin grafted to P. polionotus rejected significantly earlier than the reciprocal xenograft. All interspecific graft combinations rejected significantly earlier than intraspecific grafts. Pre‐immunization of female P. maniculatus with con‐ and trans‐specific paternal spleen cell antigens reduced fetal, placental, neonatal, and ten‐day size compared with controls. Size, weight, fertility, and graft rejection data were compared with several theoretical models. The data were consistent with the hypothesis that immunological disparity between the species could produce marked size variations in reciprocal hybrids. Multiple minor histocompatibility factors can account for large placental size and fetal mortality in Peromyscus hybrids. Physiological reproductive isolation may result from immunological differences between closely allied species.
Central organization of crustacean abdominal posture motoneurons: Connectivity and command fiber inputs
Authors: Miall R. Christopher , Larimer James L.
Published: June 2005

Intracellular recordings and Lucifer dye injections were used to locate five of the six tonic abdominal flexor motoneurons, as well as several of the extensor motoneurons in the fourth abdominal ganglion of the crayfish, Procambarus clarkii. Each motoneuron was identified by its morphology and root records, and each was characterized by its inputs from identified flexion and extension‐evoking interneurons (command fibers). Finally its connections to other motoneurons were examined by current injection experiments.

As indicated by others, the somata of most of the tonic flexor motoneurons are electrically silent; recordings were, therefore, made from neuropilar branches, but at unknown locations.

The majority of motoneurons were found to be polysynaptically connected to the command neurons, although several apparent monosynaptic excitatory and inhibitory connections were also seen. Coupling between motoneurons was confirmed, but the major functional input to the motoneurons was from premotor interneurons. Coupling between motoneurons and interneurons is also indicated by the data, and may be responsible for the inhibition of some motoneurons seen during depolarizing current injections into other motoneurons. Again, such coupling is shown to be a minor influence in the overall organization of the behavior.

The data suggest that flexion and extension behavior is predominantly organized via interneurons including the command fibers rather than by connections among the motoneurons themselves.
Effects of 25‐hydroxyvitamin D3 and 1,25‐dihydroxyvitamin D3 on embryonic chick bone in organ culture
Authors: Rosen Vicki , Clark Nancy B.
Published: June 2005

The ability of embryonic chick bone to respond to 25 hydroxy‐vitamin D3 and 1,25 dihydroxyvitamin D3 was assessed in organ culture. These metabolites were added to prelabeled chick embryo long‐bone explants, and the amount of calcium‐45 released into the medium after 24 or 48 h of hormone exposure was measured. For each time period a significant release of calcium‐45 from hormone‐treated bones was observed. The response to 25 hydroxyvitamin D3 and 1,25 dihydroxyvitamin D3 was always greater at 48 h and a clear dose‐dependency was established at this time as well. 1,25 dihydroxy vitamin D3 was the more potent resorbing agent at all concentrations tested. The results from this study suggest that vitamin D metabolites may be involved in bone regulation in the chick embryo.
Abnormal embryonic development induced by antiserum: A rapid method to isolate the responsible galactoprotein antigens
Authors: Leung Christopher C. K.
Published: June 2005

It has been well established that heterologous antiserum against whole rat kidney homogenate when injected into pregnant rats during the organogenetic period may induce abnormal embryonic development. A one‐step rapid method has been developed to isolate the responsible rat renal antigens by lectin‐affinity chromatography using soy bean agglutinin (SBA) or ricinus com‐munis agglutinin (RCA120). The purified antigens appeared to be galactoproteins with terminal nonreducing D‐galactose and/or N‐acetyl‐D‐galactosamine. Rabbit antisera produced against the galactoproteins were potent teratogenic agents.
Hormonally‐stimulated chloride transport in the eastern lubber grasshopper, Romalea microptera
Authors: Spring Jeffrey H.
Published: June 2005

Short‐circuited recta of the lubber grasshopper show an initial rapid decline in the short‐circuit current (Isc) over the first 60–90 min in vitro. This is followed by a pseudo steady state during which Isc declines slowly and steadily until a true steady state is reached after 4 h. Isc can be stimulated 4–6 fold by the addition of homogenates of corpora cardiaca (CC) or cAMP to the hemocoel‐side of the preparations. This increase in Isc is accompanied by an increase in transepithelial electropotential difference and a large drop in transepithelial resistance. Tracer studies reveal that the initial decline in Isc and its subsequent restoration to high levels is almost entirely due to changes in the active uptake of chloride from the lumen‐side (J→H). Recta maintained in vitro show a graded response to increasing doses of CC homogenates with the threshold occurring near 0.002 gland pair. In all respects these results are qualitatively and quantitatively comparable to those previously reported for the desert locust, Schistocerca gregaria. This represents the first unequivocal demonstration of hormonally‐stimulated chloride transport in an insect other than Schistocerca, and suggests that this may represent a widespread mechanism for ionic homeostasis in insects. These experiments further lay the groundwork for attempts to purify both the hormone and the chloride translocator.
Growth and development of flight muscle in the locust (Schistocerca nitens, Thünberg)
Authors: Mizisin Andrew P. , Ready Neal E.
Published: June 2005

The isometric contraction kinetics, ultrastructure, and growth of locust flight muscle that is derived from body wall muscle (metathoracic dorsal longitudinal muscle) and from limb muscle (second metathoracic tergocoxal muscle) were studied during the last three nymphal instars and in the adult 2 weeks past the terminal molt. Two distinct developmental patterns were found that correlated with use during nymphal life. The second tergocoxal muscle (TC2) is used from the time of hatching as a coxal remoter. As such, its contraction kinetics and ultrastructure are characteristic of fast, phasic muscle, which predisposes it to use in the adult as a wing levator. In contrast, the dorsal longitudinal muscle (DLM) is nonfunctional during nymphal life; contraction kinetics and ultrastructure characteristic of fast, phasic muscle develop gradually in late nymphal life until the adult kinetics are attained 2 weeks past the terminal molt. Although growth in both of these muscles occurs as the result of increases in fiber number and cross‐sectional area, there are differences in the manner in which this growth is achieved. In the TC2, there is a continuous increase in fiber number through the last three nymphal instars. In contrast, in the DLM, the increase in fiber number is nearly complete by two molts before adulthood.
Vitamin A enhances forelimb regeneration in juvenile leopard frogs Rana pipiens
Authors: Cecil Mark L. , Tassava Roy A.
Published: June 2005

The effect of retinoids on forelimb regeneration in the leopard frog, Rana pipiens, was examined by the topical application of a concentrated solution of vitamin A palmitate to the amputated left limb stumps of 30 froglets. This treatment resulted in the enhancement of regeneration; regenerative outgrowths of experimental frogs were more frequent, larger in size, and had improved morphology compared to their untreated control counterparts. We conclude that vitamin A palmitate, topically administered in concentrated dosages, exerts a positive effect on the regenerative capacity of Rana pipiens.
Mating types and mating inducing substances in Euplotes octocarinatus
Authors: Heckmann Klaus , Kuhlmann Hans‐Werner
Published: June 2005

The complex pattern of reactions between cells of ten different mating types of Euplotes octocarinatus, a fresh water ciliate closely related to E. patella, is reported. Mixture of cells of two different types leads in the majority of combinations to the formation of both heterotypic and homotypic pairs after a waiting period of about 3 hours. In a few combinations only homotypic pairs of one of the two mixed types are formed. Both homotypic and heterotypic pairs undergo meiosis and complete conjugation. Cross breeding experiments show that the ten mating types are determined by four codominant alleles (mt1, mt2, mt3, and mt4) that control the production of four matinginducing signal‐substances or gamones (G1, G2, G3, and G4). These substances are secreted into the medium and induce mature cells of certain other mating types to transform into cells that are able to unite and form conjugant pairs. We suggest that the transformation of the cells into cells ready for conjugation is triggered by the binding of gamone molecules to gamone‐specific receptors and that mature cells usually expose receptors for all gamones except the ones they produce themselves.
The distribution of polymerized actin in the rat egg and its sensitivity to cytochalasin B during fertilization
Authors: Battaglia David E. , Gaddum‐Rosse Penelope
Published: June 2005

The distribution of polymerized actin in rat eggs fertilized in vitro was determined using NBD‐phallacidin (NBD‐ph). Unfertilized and fertilized eggs exhibited a 3–5‐μm‐thick band of fluorescence that encompassed the entire cortical cytoplasm. There was no dramatic increase in the staining of the cortex in association with any component of the fertilizing sperm during its incorporation into the egg. Unfertilized eggs and fertilized eggs obtained at intervals after sperm‐egg fusion were treated with cytochalasin B (CB; 5 μg/ml) and subsequently stained with NBD‐ph. Unfertilized eggs treated with CB exhibited a continuous ring of cortical staining identical to that seen in untreated eggs. Eggs treated with CB 15 min after sperm‐egg fusion exhibited small gaps in the cortical staining pattern, whereas those exposed to CB 1 hr after fusion exhibited larger gaps and the staining pattern appeared punctate. This pattern could be seen throughout the remainder of the 7 hr period of sperm incorporation and for at least 13 hr thereafter. CB‐treated fertilized eggs that were washed to remove the drug again exhibited uninterrupted cortical staining on treatment with NBD‐ph. CB also induced the resorption of surface elevations that are normally seen on the eggs during sperm incorporation, but it did not affect the morphology of unfertilized eggs. The sensitivity to CB during fertilization coincides with the onset of a variety of egg shape changes that occur during the period of sperm incorporation (Battaglia and Gaddum‐Rosse, Gamete Res., 10:107–118, 1984a). It is probable that activation of rat eggs by the fertilizing sperm induces a change in the state of actin assembly, which might be responsible, in part, for the behavior of the egg surface during sperm incorporation and subsequent developmental events.
Photoperiodic regulation of gametogenesis and growth in the sea urchin Strongylocentrotus purpuratus
Authors: Pearse John S. , Pearse Vicki B. , Davis Karen K.
Published: June 2005

Our experiments demonstrate that both gametogenesis and growth in the sea urchin Strongylocentrotus purpuratus are under photoperiodic control. Juvenile sea urchins (4–8 mm diameter) were collected in September 1979 and reared for 18 months under two photoperiodic regimes with changing daylengths as in the natural annual cycle. One regime followed inphase (ambient) photoperiods; the other was kept 6 months out of phase with ambient photoperiods. In March of both 1980 and 1981 most of the in‐phase animals (like field animals) contained numerous gametes while the out‐of‐phase animals contained very few gametes. DNA synthesis (estimated by autoradiography with tritiated thymidine) was high in the in‐phase males and low in the out‐of‐phase males. In September of 1980, the situation was reversed. In animals exposed to two successive “winter” photoperiod regimes, gamete production continued for 6 months; in those exposed to two successive “summers,” there was little gamete production. These experiments suggest that either long days inhibit gametogenesis or short days enhance it. The normal peak of body growth in the summer and fall was also shifted 6 months out of phase in animals kept on the out‐of‐phase photoperiod regime; this shift was reflected in size, in weight, and in the growth zones of the skeletal plates. Feeding rates did not differ between animals on the two photoperiod regimes, suggesting that photoperiod does not influence energy intake but rather determines whether energy is allocated to body and gonad growth or to gametogenesis and gamete maintenance.
Protein gradients in byssal threads of some marine bivalve molluscs
Authors: Mascolo J. M. , Waite J. H.
Published: June 2005

Many marine bivalve molluscs produce byssal threads for attachment to solid substrata. Small (< 10 mm) consecutive sections of the byssal threads of Mytilus edulis, M. californianus, Geukensia demissa, Atrina vexillum, and A. rigida were analyzed by amino acid analysis to determine if chemical composition remains constant as a function of location in thread segments. Nonlinear longitudinal protein gradients, probably involving collagen and an elastic protein, were found in the Mytilus species. In these, collagen peaks in the distal third of the thread. In Geukensia and the Atrina species, although the two differed greatly in composition, there is a clear nonvariability in composition of the thread within each species as a function of location in the thread. The adhesive plaque at the tip of the thread of all species examined differs substantially in composition from the remainder of the thread. Protein gradients in the threads of some bivalves may reflect specific adaptations evolved to respond to exposed habitats in high‐energy environments.
Developmental analysis of lipids from wild‐type and adipose60 mutants of Drosophila melanogaster
Authors: Teague Barbara Dean , Clark Andrew G. , Doane Winifred W.
Published: June 2005

A comparative developmental analysis was made of lipids from wild‐type and adipose60 (adp60) mutants of Drosophila melanogaster. The lipid content and fatty acid profiles of late third instar larvae, pupae, and mature adults were characterized in methanol:chloroform extracts utilizing thin layer and gas‐liquid chromatography. Total lipid content of mutant adults was approximately twice that of the wild‐type, but no genotypic differences in lipid content were seen in earlier developmental stages. No sexual dimorphism was observed in total lipid content, although fatty acid profiles revealed some sexual differences. Many stage‐specific differences in fatty acid profiles and lipid content were developmentally associated with each genotype. Mutants tended to retain the larval phenotype in lipid content and, to a lesser extent, in fatty acid profile. In comparison to wild‐type, mutants tended to have increased lipid saturation, especially in 16‐carbon fatty acids in mature adults and in 18:0 fatty acids in late larvae and pupae. No significant difference between the mutants and wild‐type appeared in the developmental profiles for 14:1 fatty acid isomers. Hence, adp60 does not alter the desaturation‐elongation pathway, a secondary pathway for fatty acid desaturation in Drosophila, which received support from this analysis.
Spawning cycles of the Gulf killifish, Fundulus grandis, in closed circulation systems
Authors: Hsiao Shyh‐Min , Meier Albert H.
Published: June 2005

Gulf killifish, Fundulus grandis, spawned daily in aquaria held on 12‐h daylengths and 23°C. However, the number of eggs spawned varied from one day to another. Statistical analyses of the data revealed the presence of 13‐day (semilunar) cycles of spawning in five of seven aquaria that persisted for as long as 4 months. In addition to semilunar cycles, short (about 3 days) cycles were also common. Because each aquarium usually held 21 females, the existence of both 3‐day and 13‐day cycles suggests that there was synchronization within each group. There was also synchronization of 13‐day cycles between aquarium groups with a common recirculating water supply. Although the 13‐day cycle may be essentially an endogenous free‐running semilunar rhythm, exogenous timing of this cycle is supported by the strong coherence between it and the concurrent high‐tide cycles on the Louisiana Gulf coast.
Effect of cutting the zona pellucida on the pronuclear transplantation in the mouse
Authors: Tsunoda Y. , Yasui T. , Nakamura K. , Uchida T. , Sugie T.
Published: June 2005

A new and reliable pronuclear transplantation procedure for the mouse egg has been developed by McGrath and Solter ('83). To overcome the technical difficulties of such a procedure, especially in uniformly preparing enucleation pipettes and in reducing damages during micromanipulation, we have examined the effect of cutting the zona pellucida of the eggs. By making a slit in the zona of an egg, the time for pipetting and exchange of pronuclei between eggs was shortened because the sharp tip of the pipette was not necessary. Although the proportion of pregnant recipients and young obtained after transfer of pronuclear transplanted eggs cultured for 1 day or 3 days was quite low, it was significantly increased (70% for pregnancy rate and 32% for the young) following transfer of eggs cultured for 4 days. These values were comparable with those after transfer of unoperated eggs cultured to morulae and blastocysts.
Studies of three major proteases associated with guinea pig sperm acrosomes
Authors: Arboleda Carlos E. , Gerton George L.
Published: June 2005

The major proteases associated with guinea pig sperm were investigated by using immunological and electrophoretic techniques. Three major proteases were detected following sodium dodecyl sulfate‐polyacrylamide gel electrophoresis in gels containing 0.1% gelatin. These enzymes had molecular weights of 47,000, 34,000, and 32,000 relative to reduced protein standards and 58,500, 40,000, and 37,500 relative to unreduced standards. All three protease activities were present in acid extracts of sperm, detergent extracts of sperm, and the soluble acrosomal components of sperm released following induction of the acrosome reaction with the Ca2+‐ionophore A23187. As determined by indirect immunofluorescence, an antibody to purified boar acrosin specifically cross‐reacted with the acrosomes of guinea pig sperm. Decreased fluorescence was associated with sperm that had lost their acrosomes. Immunoblot analysis demonstrated that this antibody reacted with the 47,000 Mr protease but not the 32,000 and 34,000 Mr proteases. All three proteases were maximally active in the pH 7.0–8.5 region and were inhibited by classical inhibitors of acrosin activity. During a 3‐hour incubation period, MgCl2 (10 mM) inhibited the activities of the 32,000 and 34,000 Mr proteases while the 47,000 Mr protease was stimulated. Although these proteases shared properties that would classify them as trypsin‐like proteases, only the 47,000 Mr protease could be definitely classified as a member of the proacrosin‐acrosin family based upon cross‐reaction with an antibody to purified boar acrosin.
Mechanisms regulating the ovarian cycle in the frog Rana cyanophlyctis: Effect of unilateral ovariectomy, season, feeding, human chorionic gonadotrophin, and estradiol‐17β
Authors: Saidapur S. K. , Prasadmurthy Y. S.
Published: June 2005

Effects of 30‐day unilateral ovariectomy (ULO) on compensatory ovarian hypertrophy (COH) was studied in adult frog Rana cyanophlyctis in relation to reproductive phase/season, feeding, and treatment with human chorionic gonadotrophin (HCG) or estradiol‐17β. Compensatory growth of the remaining ovary was assessed in terms of weight as well as changes in the dynamics of the pool sizes of different oocytes viz., first growth phase (FGP), medium‐sized second growth phase (MSGP), large‐sized second growth phase (LSGP), and atretic oocytes. The frogs were fed with live guppies 6 days a week. The effect of underfeeding on COH was studied in the frogs fed once a week. The ovaries removed at operation and those of the sham‐operated frogs were used for comparison (controls).

COH occurred in both pre‐ and postbreeding phases (February and November, respectively). In both instances follicular atresia was greatly reduced. In February, COH was due to recruitment of both MSGP and LSGP oocytes. The number of these oocytes increased significantly over controls, and the ovarian weight nearly doubled. However, in November COH occurred because of an increase in FGP oocytes and therefore total oocytes, but there were no changes in the ovarian weights. Administration of 20 IU HCG (6 days a week) had no influence on the basic pattern of COH‐response exhibited by the remaining ovary in relation to reproductive phase/season, but it increased the recruitment of oocytes, i.e., FGP oocytes in November and SGP oocytes in February. Follicular atresia was drastically reduced with HCG. Underfeeding or treatment with estradiol‐17β abolished the COH in both February and November. In addition, follicular atresia increased markedly in the remaining ovary.

The findings suggest that reproductive phase and season influence the COH‐response of the remaining ovary and ovarian sensitivity to gonadotrophins. Seasonal changes in the pool sizes of FGP and SGP oocytes in the frog appear to be governed by the interactions between the various factors such as gonadotrophins, ovarian sensitivity, and season. The rate of follicular atresia is primarily regulated by the changing levels of gonadtrophins. Adequate feeding is essential for proper ovarian function in the frog. The present study suggests that for determining COH, especially in seasonal breeders, it is necessary to consider the pool sizes of different‐stage oocytes since ovarian weight alone is not a reliable criterion.
Inhibition of LH‐induced and spontaneous meiotic maturation in mouse oocytes by Nα‐tosyl‐L‐lysine chloromethylketone
Authors: Hashimoto Naohiro , Kishimoto Takeo , Nagahama Yoshitaka
Published: June 2005

The effect of Nα‐tosyl‐L‐lysine chloromethylketone (TLCK), an inhibitor of trypsin‐type proteases, on luteinizing hormone (LH)‐induced and spontaneous meiotic maturation and follicular production of cAMP in mice was determined. When follicle‐enclosed mouse oocytes were incubated with LH (1μg/ml), they underwent the breakdown of the germinal vesicle (GVBD). TLCK (0.02–0.5 mM) inhibited LH‐induced GVBD in folliculated oocytes. The concentration (0.5 mM) of TLCK that inhibited LH‐induced GVBD did not significantly suppress LH‐induced cAMP production by follicle cells.

The effect of TLCK on spontaneous maturation in cumulus cell‐enclosed and denuded oocytes was also determined. TLCK strongly inhibited spontaneous maturation in denuded oocytes only if it was added to the incubation medium for 1–3 h before oocytes were liberated from the follicular tissue. The inhibition of oocyte maturation by TLCK was significantly greater in cumulus cell‐enclosed oocytes than in denuded oocytes, either with or without preincubation with TLCK. These results suggest that trypsin‐type protease in oocytes participates in the process of meiotic maturation in mouse oocytes.
Nuclear basic proteins in mature testis of the ascidian tunicate Styela montereyensis
Authors: Chiva M. , Rosenberg E. , Kasinsky H. E.
Published: June 2005

We have studied the basic protein content of nuclei in mature testis of the hermaphroditic, solitary ascidian tunicate Styela montereyensis. Cytochemically, tunicate sperm nuclei stain in a manner similar to that of the mussel Mytilus, indicating the presence of type 3 intermediate sperm basic proteins in the classification scheme of Bloch (Genetics [supplement] 61:93–111, 1969). Biochemically, these sperm nuclei possess basic proteins that are very rich in arginine (ca. 50 mole %) and moderately rich in lysine (ca. 17 mole %). These basic proteins are therefore protamines according to the definition of Subirana (The Sperm Cell, Martinus Nijhoff BV, The Hague, pp. 197–213, 1983). These protamines replace either the major part or all of the somatic histones in the testis. The very lysine‐rich H1 histones of S. montereyensis testis, some of which are also rich in arginine (22 mole %), display a number of electrophoretic components with varying mobilities. Comparing these characteristics of the sperm basic proteins in S. montereyensis with those in echinoderms and vertebrates indicates some similarities to each of these deuterostome phyla representing distinct evolutionary lines. Thus, the presence of arginine‐rich protamines in S. montereyensis and the displacement of somatic histones in sperm nuclei by these protamines are typical of many vertebrate species. Variation in the H1 family of very lysine‐rich histones in S. montereyensis testis, including some H1 histones with an elevated arginine content, can also be seen in many echinoderms.