bluuebunny/crossref_metadata_2025 huggingface dataset:
An attempt to reconstruct evolutionary changes in the cellular DNA content of lungfish
Authors: Thomson Keith Stewart
Published: June 2005

Living lungfish (Osteichthyes: Dipnoi) are known to have a very large cell size and unusually large quantitities of DNA per cell (up to 40 times the mammalian content). The pattern of evolution of cell size in fossil Dipnoi has been examined in order to see what light it might possibly shed on the question of the origin and evolutionary significance of DNA multiplication in Dipnoi. In the Devonian, cell size was low and it increased only in the Carboniferous when the major dipnoan morphological and taxonomic diversifications were ebbing. If it can be shown that there is a functional relationship between cell size and DNA content, then the data suggest that increase in cellular DNA content have a retarding rather than stimulating effect on dipnoan evolution. Since large cell size and (by inference) high cellular DNA content are not a primary feature of the dipnoan stock, it is suggested that in those other vertebrates, such as certain amphibians, which show the same phenomenon, it is also a secondary feature.
The effects of nerve growth factor on bullfrog tadpoles (Rana catesbiana) after limb amputation
Authors: Weis Judith S.
Published: June 2005

Tadpoles of the bullfrog, Rana catesbiana, lose the ability to regenerate limbs at a very early stage of development. Non‐regenerating limbs either show rapid healing of connective tissue over the cut surface with no breakdown of skeletal structures, or else show dedifferentiative processes in the cartilage but the rudimentary blastema formed does not proliferate, and becomes separated from the epidermis by the regrowth of the connective tissue layer. This condition is termed the “critical stage.” When tadpoles were treated with NGF, enlargement of spinal ganglia resulted due to an increase in cell number. The density of nerve fibers in the limbs was likewise increased. This increase in nerve supply to the limbs resulted in a greater incidence of critical stage limbs over non‐regenerating ones, and in several cases, produced limbs which appeared histologically to be, in fact, regenerating.
The haploid syndrome in isogenic haploid frog embryos of Rana pipiens derived by nuclear transplantation
Authors: Dasgupta Sanjoy , Matsumoto Lloyd
Published: June 2005

The majority of haploid frogs are non‐viable and few survive past early larval stages. While animals vary with respect to specific abnormalities, they succumb to the variety of defects which collectively comprise the haploid syndrome. This poor viability has been ascribed to unmasked lethal and semi‐lethal genes or to alterations in the nucleocytoplasmic ratio. This investigation was designed to test these hypotheses by determining the uniformity of anomalies in clones of isogenic haploid embryos.

Animal hemisphere nuclei of stage 10 androgenetic haploids of Rana pipiens were transplanted into activated and enucleated eggs of uniform size. Haploid embryos were selected from eggs whose cleavage times coincided with those of the fertilized controls. Genetically identical haploid embryos displayed differences in the variety as well as the severity of abnormalities. Thus, specific lethal genes are not responsible for the variability in defects seen in the haploid syndrome. We ascribe haploid inviability and variations within isogenic clones to a lack of heterozygosity of the haploid nucleus with resultant inability of the haploid nucleus to function in a heterogeneous environment, i.e., the egg cytoplasm.
Recovery and abscopal effects after inhibitory x‐irradiation in earthworm regeneration
Authors: Moment Gairdner B.
Published: June 2005

A seven step series of whole body irradiations beginning with 1,872 R and ending with 20,000 R showed that 10,000 R is not sufficient to block posterior regeneration from the fiftieth segment in the barnyard earthworm, Eisenia foetida but that 20,000 R is completely effective.

With partial body irradiation at 20,000 or 30,000 R, if the five segments adjacent to the cut surface are exposed and the rest of the body shielded, there is no regeneration by the end of four weeks when controls have regenerated a mean of 34 segments and a minimum of 23 and stopped forming new ones. At the end of seven or more weeks all the partially irradiated worms had recovered and regenerated up to means of 17.3, 20.0, and even 26.3 segments.

An abscopal effect was clearly evident in worms in which the first 40 segments were irradiated and the rest of the body, including the ten segments adjacent to the cut surface, shielded. All such worms regenerated without appreciable delay but markedly fewer segments than the controls. The question then arises as to why regenerating blastemas which are fully competent to regenerate a mean of 25 segments do not continue to proliferate until they have formed about 35 like the controls.
Differential sensitivity to hibernation of early and late events in development of the immune response
Authors: Jaroslow Bernard N. , Serrell Beverly A.
Published: June 2005

Ground squirrels, Citellus tridecemlineatus, were immunized with a single intraperitoneal injection of sheep red cells four days before, two days before, during and upon arousal from hibernation. The number of antibody‐forming cells per spleen was determined at different times during 56 days of hibernation and during the first week following arousal. All phases of the response, i.e., latent period, proliferative phase, declining phase, were slowed during the hibernation period and we concluded that most of the development occurred during the short periods of spontaneous arousal. The latent period, as compared to the other phases, was the most sensitive to retardation by hibernation. We believe that the resumption of development of the immune response during this phase is relatively delayed upon arousal because the early differentiating cells entered a quiescent state better adapted to hibernation whereas the later cell types did not.
α‐tocopherol in males of the rotifer Asplanchna sieboldi: Its metabolism and its distribution in the testis and rudimentary gut
Authors: Gilbert John J.
Published: June 2005

New‐born males produced by mictic females induced and cultured with emulsified dl‐α‐tocopherol‐5‐methyl‐H3 were extracted with acetone. A thin‐layer chromatogram of the extracted residue was divided into 20 1‐cm fractions which were analyzed for radioactivity in a liquid scintillation spectrometer; 100% of the tritium‐labeled lipid co‐migrated with authentic α‐tocopherol. Since known α‐tocopherol metabolites have migration characteristics different from α‐tocopherol in the chromatography system used, it was concluded that only undegraded α‐tocopherol was present in the males.

The efficiency of extraction of tritium label from 42 males was 89%, and 132 DPM were recovered from the thin‐layer chromatogram. Therefore, each male contained about 5 × 10−16 moles, 0.2 pg, or 107 molecules of α‐tocopherol.

The distribution of tritium‐labeled α‐tocopherol in embryonic and new‐born males produced by mictic females induced and cultured with emulsified dl‐α‐tocopherol‐5‐methyl‐H3 was analyzed by autoradiography. Background‐corrected mean grain density values showed that, for two different new‐born males, the amount of label in the testis was 3.7 and 6.7 times that in the rudimentary gut. Grains over the testis appeared to be randomly distributed while those over the rudimentary gut were primarily over the periphery.

A semi‐quantitative analysis of mictic females with male embryos in different stages of development showed that only in well differentiated males were grain densities over the testis noticeably greater than those over the rudimentary gut. In younger embryos grains appeared to be randomly distributed over the entire embryo. Grain densities over the rudimentary gut in males about to be born were much lower than those over embryos in earlier stages of development. These results, together with electron micrographs of the testis and rudimentary gut of new‐born male Asplanchna and information available on the subcellular distribution of α‐tocopherol in vertebrates and plants, suggest that during late development of the male embryo α‐tocopherol‐rich organelles such as mitochondria are lost from the degenerating tissue from which the rudimentary gut of the new‐born male is derived.

The results obtained are consistent with the hypothesis that α‐tocopherol is essential for spermatogenesis or male fertility in A. sieboldi and that for this reason the species has evolved its requirement of α‐tocopherol for mictic female production.
Induced chimaerism by transplanting embryonic cells into mouse blastocysts
Authors: Moustafa Laila A. , Brinster R. L.
Published: June 2005

Embryonic synchronous and asynchronous cells were successfully transplanted into preimplanted mouse blastocysts. At 15–17 days of fetal development, 19% (32/167), 15% (20/130) and 3% (4/117) of the fetuses expressed chimaerism of the ocular pigmentation when transplanted cells were 0, 48, and 96 hours asynchronous respectively. At birth and during postnatal development, 15% (23/153) and 13% (14/111) of the young expressed chimaerism of ocular pigmentation, coat color, and/or functional germ lines when transplanted cells were 0 and 48 hours asynchronous respectively. Five animals from synchronous and two animals from asynchronous cell transplants were chimaeric in functional germ lines but resembled recipient blastocysts in phenotype color. One overtly chimaeric male had progeny with color phenotype of the albino donor cells only. This report provides evidence that transplanted asynchronous as well as synchronous embryonic cells do participate in the final structure of the embryo. In addition, the results of these studies suggest that the micrurgy and transplantation of the cells does not affect substantially subsequent development of the recipient blastocysts.
The influence of ovine follicle stimulating hormone (FSH) and luteinizing hormone (LH) on the male reproductive system and the skin of the mediterranean Blenniid fish Blennius sphinx (valenciennes)
Authors: Blüm Volker
Published: June 2005

The Mediterranean Blenniid fish Blennius sphinx has a unique male reproductive system: the testes lie close to voluminous lipid bodies through which the sperm must pass. The tubules, through which the sperm travel, lead to a collection duct opening ventrally into locally enlarged sperm ducts. These taper off caudally and join in an unpaired terminal section which opens into a genital papilla. Slightly posterior to the union, the duct forms two blind pouches extending laterally to the caudal third of the testes. In addition, during spawning, Blennius sphinx shows a glandular system of unknown function in the first and second spines of the anal fin.

In this paper, the reactions of the sex‐linked structures described above, and of the mucous cells in the epidermis of post‐spawning fishes, to injections of mammalian FSH and LH are studied.

By LH‐treatment the proportion of the animals with fully active testes is increased from 36% (controls) to 83%.

The height of the lipid body is increased about 26% by LH‐injections, as compared with the controls. This effect is correlated with an increase in the size of the lipid vacuoles of about 28%.

In the epithelium of the paired portions of the sperm duct, LH promotes the formation of aldehyde fuchsin‐positive granules in the cells. The proportion of this type of secretion rises from 18% (controls) to 68% after LH‐treatment. In the terminal unpaired part of the sperm duct, within the genital papilla, the epithelium is thickened by about 38% by this hormone.

Injections of LH decrease the height of the blind pouch epithelium, which is well developed, and actively secreting in most of the controls. They also suppress secretion and vascularisation in this structure.

LH promotes the formation of the anal gland system, increasing the proportion of the animals with maximally developed glandular systems from 0% (untreated controls) or about 17% (H2O‐treated controls) to 91%. This effect is correlated with an increase of the diameter of the single glands of about 40%. This is also the case in FSH‐treated fishes (23%). The number of the mucous cells in the epidermis decreases by 46% and 45% after FSH‐ and LH‐treatment, respectively.

In no case were the effects strictly correlated with the hormone dose.

The problems of the action of mammalian gonadotrophins, especially FSH, in fishes; the possible functions of the organs associated with the male genital tract of Bl. Sphinx, and the possible role of the mucous cells in the osmoregulation of fishes are discussed.
The activity of microtubules and microfilaments in neurulation in the chick
Authors: Karfunkel Perry
Published: June 2005

During neurulation, the cells of the chick neural anlage elongate and become wedge‐shaped. Microtubules are seen aligned parallel to the cells' long axes, and bands of microfilaments are seen in the cell apices. If stage 8 embryos are cultured in the presence of colchicine, the cells of the brain anlage round up and the neural folds move away from each other. In the posterior part of the neural anlage, cells fail to elongate, and neural folds never form in this region. If such embryos are cultured in the presence of cytochalasin B, the cells of the brain anlage remain elongate but the neural folds separate from each other. The cells of the posterior part of the neural anlage elongate in the presence of cytochalasin, but the neural folds never form in this region. These results constitute evidence that microtubules effect the cell elongation and microfilaments effect the apical constriction of cells which normally accompany neurulation. These changes in cell shape appear to be responsible for the elevation and mediad folding of the neural folds.
Skin allografts in the newt, Notopthalmus viridescens: Cessation of blood flow as an indicator of rejection,
Authors: Hightower James A. , St. Pierre Ronald L.
Published: June 2005

Histological sections and surface views of skin allografts from newts were examined. It was determined that complete cessation of blood flow through the allografts was a valid indicator of graft rejection.

The following sequence of events was detected within allografts as they were rejected; (1) primary vasodilation 8.4 ± 3.6 days after grafting; (2) re‐establishment of circulation at days 11.3 ± 3.5 after grafting; (3) signs of rejection (viz., secondary vasodilation, stasis and hemorrhage) at days 20.9 ± 5.0 after grafting, and (4) complete rejection at days 36.1 ± 7.0. There was no evidence of sexual dimorphism in any of the newts examined with regard to skin allograft rejection.
Deployment of maternal template during early amphibian embryogenesis
Authors: Malacinski George M.
Published: June 2005

The electrophoretic characteristics of the proteins synthesized during the early stages of Rana pipiens embryogenesis were determined. Very minor quantitative changes were observed in the spectrum of proteins synthesized during development from the unfertilized egg through the 32‐cell stage. At the mid‐ and late cleavage stages, however, a pronounced increase was observed in the rate of synthesis of some proteins which very previously synthesized at relatively low rates.

The qualitative features of protein synthesis in early cleavage stage embryos which lacked functional chromosomes resembled control nucleated embryos at similar morphological stages; therefore the translation of maternal template appears to specify the types of proteins synthesized during those early stages of development. In partial blastulae derived from enucleated eggs, the increased rate of synthesis of specific proteins observed in control embryos was not detected. The deployment of specific maternal templates at the blastula stage seems to require the presence of functional chromosomes.
Gel filtration of the sperm attractants of some marine hydrozoa
Authors: Miller Richard L.
Published: June 2005

Elution patterns of sperm chemo‐attractants isolated from female hydroids of the genera Campanularia, Gonothyrea, Tubularia and Clava were obtained by comparative gel filtration chromatography. Generally one major and one minor peak of activity were obtained for each of the species used, except Gonothyrea which yielded two large active peaks. The Rf values of these peaks fall into two non‐overlapping groups. The first group consists of the major peak obtained from Campanularia calceolifera, the first major peak from Gonothyrea and the minor peak obtained from each of the three species of Tubularia, all of which have Rf values near 0.7. The second group consists of the major peaks from the three species of Tubularia, the second major peak from Gonothyrea, the minor peak from C. calceolifera, and the major peak from Clava, all of which have Rf values near 0.5. Separation of mixtures of some of the attractants was possible using this method.

Correlation between chromatographic elution position and species‐specificity determined by testing the extracts from the various species against live sperm, is not perfect in all cases, in part, at least, because gel filtration is not capable of separations other than on the crude basis of molecular size. Gonothyrea and Campanularia calceolifera extracts and sperm show cross‐reactivity and their active agents elute together during chromatography. The same is true for the three species of Tubularia tested. However, the second Gonothyrea peak elutes at the same position as the major peak of Tubularia activity, but these genera do not attract each other's sperm. These results suggest that methods other than chemotaxis are used by many hydroids to prevent exposure of eggs to sperm from the wrong species and that more specific separation methods will have to be used to determine the molecular basis for chemotactic specificity in hydroids.
The antigenic pattern of the developing brain of the zebrafish, Brachydanio rerio
Authors: Singh Lakheram , Laale Hans W.
Published: June 2005

Developmental stages, from eight cells to 28 days post‐hatching, of the zebrafish, Brachydanio rerio, were analysed by immunoelectrophoresis with unabsorbed and absorbed rabbit antiserum to adult zebrafish brain. From the earliest embryonic stage to the oldest post‐hatching stage tested, a developing antigenic pattern was recognizable. Six antigens, found to be consistently present in all stages, exhibited no observable variation in electrophoretic mobility or diffusion rates. Of four other antigens present in the earliest stage analysed, one appeared intermittently throughout subsequent developmental stages. Three antigens appeared consistently, but showed variations in electrophoretic mobility at different stages. Fourteen ‐antigens, two of which were transitory, appeared during development, adding to the complexity of the antigenic pattern. Including all stable and variant forms of antigens, a total of 30 antigens was detected from the earliest embryonic stage to the oldest post‐hatching stage tested.
Regulative development in the pulmonate gastropod, Lymnaea palustris, as determined by blastomere deletion experiments
Authors: Morrill John B. , Blair Claudia A. , Larsen William J.
Published: June 2005

To determine the regulative ability of Lymnaea eggs one or more cells were deleted by puncturing or shaking eggs at the 2−, 4−, 8− and 16‐cell stages. Normal snails developed from: one/two, three/four, and two/four embryos; from 8‐cell embryos in which one, two, or three cells of the first quartet of micromeres or one or two macromeres were deleted; and from 16‐cell stage embryos in which one cell of the second quartet of micromeres or one macromere was deleted. Only one/two embryos that cleaved as though they were whole eggs up to the 24‐cell stage developed normally. Normal development of other partial embryos was associated with partial cleavage. Developmental abnormalities of partial embryos included death in the cleavage period; arrested gastrulae; trochophores, or veligers; and abnormal snails with head malformations, everted stomodea, or conical shells.

Comparing the results with deletion experiments in other molluscs and with deductions from descriptive studies on the Lymnaea egg, we propose that the regulative ability of partial embryos depends on the rearrangement of cells relative to the D macromere before inductive activities begin at or after the 24‐cell stage.
Role of islet tissue in the cold‐induced hyperglycemia of the killifish, Fundulus heteroclitus
Authors: Umminger Bruce L. , Bair Roy D.
Published: June 2005

Islet tissue histology and serum glucose concentrations were examined in salt‐water‐adapted killifish, Fundulus heteroclitus, acclimated to 20°C and to − 1.5°C for one and ten days. Exposure to subzero temperatures produced a hyperglycemia accompanied by hypertrophy and degranulation of alpha cells in the islets and by atrophy of the islet beta cells with no changes in granulation. The cold‐induced hyperglycemia presumably resulted from an increase in circulating levels of glucagon and from a failure of the beta cells to release insulin.
Photoperiod and crowding effects on testicular serotonin metabolism and lack of effects on melatonin synthesis in Uinta ground squirrels (Spermophilus armatus)
Authors: Frehn John L. , Urry Ronald L. , Balph David F. , Ellis Legrande C.
Published: June 2005

The photoperiod (i.e., constant light vs a 14/10 hour light/dark cycle) and “physical” crowding (group caging) on Uinta ground squirrels (Spermophilus armatus) was investigated to ascertain what effects these two environmental parameters would have on testicular metabolism of serotonin (MAO activity) and melatonin synthesis by pineal glands in organ culture. Testicular MAO activity was decreased by both constant light and crowding. Melatonin synthesis was not significantly affected by either treatment. These data are consistent with the normal reproductive activity of unconfined ground squirrels where the testes normally develop while the animals are in their burrows under constant darkness. Failure of the pineal gland to respond to constant darkness appears to be an adaptation of the animal to eliminate this source of antigonadal activity that would serve to retard gonadal development while the animal is in constant darkness. Failure of the testes to respond to a 14/10 hour Light/Dark cycle indicates that the hypothalamus is insensitive to lighting as a triggering mechanism for initiating testicular development.
Use of chimeras to transmit lethal genes in the mouse and to demonstrate allelism of the two X‐linked male lethal genes jp and msd
Authors: Eicher Eva M. , Hoppe Peter C.
Published: June 2005

The uses of experimental chimeras to transmit lethal genes are discussed. As an example, the X‐linked lethal mutation jp was genetically transmitted by a chimeric male. This male produced abnormal offspring when bred to jpl + and msd/ + females. Thus, allelism of the mutations jp and msd is proven and the symbol for msd should be changed to jpmsd.
Lymphoid changes during antibody synthesis in larval Rana catesbeiana
Authors: Baculi Buena S. , Cooper Edwin L.
Published: June 2005

Thymectomy, splenectomy and/or lymphadenctomy affect antibody synthesis to a soluble antigen, hemocyanin, in bullfrog larvae. Tadpoles were divided into seven groups and these into three subgroups: Experimentals— A: operated and immunized by hemocyanin or allografts; Controls—B: operated but non‐immunized; Controls—C: one group unoperated and immunized. With regard to the spleen, good correlation between antibody titer and degree of splenic regeneration was observed. Structurally, the white pulp contained numerous small lymphocytes but in the red pulp, the number of blast cells and lymphocytes increased. The spleen may be the main organ involved in larval antibody synthesis. The lymph glands seem secondary; lymphadenectomized larvae showed no regeneration of lymph glands and antibody titers were lower than in sham‐operated controls. Compensatory hypertrophy of the remaining gland in unilaterally lymphadenectomized larvae was absent. With regard to cell types, lymph glands showed a picture similar to active nodules, i.e., the core of the cords consisted of blast cells and larger lymphocytes surrounded by layers of small lymphocytes. Thymic regeneration occurred in all tadpoles and, of much interest, titers were always highest in this previously thymectomized group. Observations on thymectomized tadpoles suggest a thymus stimulating effect on certain peripheral lymphoid organs, notably the spleen. The thymus in frog larvae may be important in antibody synthesis during later stages when the capacity to develop cellular immunity has already matured.
Experimental studies on a new lethal trait in Mexican axolotls of the Wistar Institute white strain
Authors: Humphrey R. R.
Published: June 2005

An additional lethal gene (y) in white Mexican axolotls of the Wistar Institute stock, first discovered in 1965, is believed to have arisen by mutation only two generations earlier. Larvae homozygous for y develop normally for about two weeks after hatching, and become recognizable at that time by the cessation of growth in the forelimbs. Death occurs at the age of five to seven weeks.

Experimental studies (transplantation, parabiosis) suggest that gene y deter‐
mines metabolic deficiencies in all cells of the embryo. Forelimb transplants
produce limbs which cease growth and differentiation and persist as short
stumps which, even though partially replaced by host tissues, lack capacity
for normal differentiation or for regeneration after amputation. Transplants
including Wolffian duct and the primordia of gonad and mesonephros produce
non‐functional mesonephric tubules and gonads in which the germ cells
degenerate and disappear. In parabiosis with a normal cotwin a mutant larva
may be kept alive for several months but shows extensive degeneration and
disappearance of muscle fibers, and eventual loss of gastrointestinal epithelium
and glands, gonads, and mesonephros. The growth of the normal cotwin is
greatly inhibited, probably because its vital organs are overburdened as those
of its lethal partner cease to function. Only one pair reached the age of six
months, with the normal member attaining a length of only 25 mm, one‐fourth
or less the length of normal larvae of that age.
Relationship between pattern of cell migration from the germinal layer and changing patterns of differentiation in the lizard epidermis
Authors: Flaxman B. A. , Maderson P. F. A.
Published: June 2005

During renewal of the lizard epidermis, the rate of new cell production varies cyclically from a low level (resting stage) to a high level (renewal stage). Renewal involves the formation and shedding of an “epidermal generation” in which cells of the outermost layers synthesize beta keratin whereas cells of the inner layers synthesize alpha keratin. The cells are derived sequentially from a morphologically homogeneous basal layer. Tokay geckos were injected with a single pulse of tritiated thymidine at the end of the resting stage, 24 hours prior to the onset of epidermal renewal. Sequential biopsies were taken and analyzed by radioautography. Twenty‐four hours after the pulse, labeled nuclei were found only in the basal layer. During the subsequent four to five days, both labeled and unlabeled mitoses were present in the basal layer. Although at least seven new layers of cells were added above the basal layer during this same four to five day period, none of their nuclei were labeled. Most of these cells would normally subsequently synthesize beta keratin. The first cells with labeled nuclei emerged from the basal layer after this four to five day delay. These cells would normally go on to synthesize alpha keratin. The labeling index in the basal layer, which was less than 10% at 24 hours after injection, rose to about 50% and fell coincident with emergence of cells destined to form alpha keratin. Thus, these cells must have divided more than once before leaving the basal layer. The studies indicate that the pattern of migration of cells from the basal layer plays an important role in the emergence of a new pattern of differentiation.
Regeneration of sialic acid‐containing components of embryonic cell surfaces
Authors: Collins Michael F. , Holland Karen D. , Sanchez Reynaldo
Published: June 2005

Sialic acids such as N‐acetylneuraminic acid have been found at the surfaces of various cells. They may play an important role in intercellular adhesion and hence in animal morphogenesis. This work demonstrates sialic acid at the surfaces of seven‐day chick embryo neural retinal cells and its regeneration after enzymatic removal.

Neural retinas were excised and dissociated with trypsin. The cells were
incubated in a solution of Vibrio cholerae neuraminidase. The enzymatic treat
ment released sialic acid which was assayed by thg thiobarbituric acid method
of Warren. The enzymatic treatment also reduced the cellular electrophoretic
mobility from 1.1 to 0.4 × 10−4 cm/sec/volt/cm measured in 0.067 molar phos
phate buffer at pH 7.5.

Cells which had been treated with neuraminidase were cultured in a modified
Eagle's minimum essential medium for up to 24 hours. During the period of
culture, the replacement of surface material was observed in two ways. First
was the progressive return of electrophoretic mobility to the pre‐neuraminidase
level. Second was the progressive return of sialic acid at the cell surface to the
original level. The latter was shown by second neuraminidase treatments and
determinations of sialic acid released.

Effects of neuraminidase upon the reaggregation of cells cultured on a
gyratory shaker in Eagle's medium were investigated. Neuraminidase was not
effective for dissociation of neural retina.
Host‐transplant relationship of cultured mouse embryos
Authors: Fisher D. L. , Smithberg M.
Published: June 2005

The host‐transplant relationship of cultured mouse embryos was studied in mice of strain 129/SvSl. Immature females were superovulated and embryos obtained at the four cell stage were cultured in vitro for 48 hours using Brinster's technic. At the conclusion of the culture period, 80.9% had developed to blastocysts. These were transplanted by direct uterine insertion into one to four day pseudopregnant nulliparous hosts three to seven months of age.

Transplants to a one day host are lost 24 hours after transplant. The trans
planted four day old embryos implant and develop into fetuses most success
fully in two day pseudopregnant hosts. The blastocysts are retained in the
uterine lumen for up to 72 hours before implantation. Transplantation to three
day hosts allowed fetal development but at a much lower percentage than with
two day hosts. Blastocysts were found to be retained in the uterine lumen
for up to 48 hours. A very low percentage of transplants to four day hosts did
implant, but no fetal development occurred. It is apparent that a critical
period of adjustment and interdependence between embryonic development
and uterine receptivity is required before implantation of the cultured embryo
can proceed. Embryos which implant develop according to post implantation
age, not embryonic age, and are delivered according to the normal uterine
gestation time.
Sarcomere length increases in developing crustacean muscle
Authors: Govind C. K. , Atwood H. L. , Lang Fred
Published: June 2005

Measurements of sarcomere length in the tonic claw opener muscle and in the tonic (superficial) and phasic (deep) abdominal extensor muscles in crayfish and lobster revealed a two‐fold increase from the time of hatching to the adult stage. Initially sarcomere length is longer in tonic than in phasic muscles and the tonic muscles have a faster rate of increase than the phasic muscles.
Phosphatase active antigens in sea urchin eggs and embryos. II. A comparison between the activities in unfertilized eggs and plutei
Authors: Westin Monica
Published: June 2005

Phosphatase activities in sea urchin eggs and plutei were investigated by means of histochemical staining of immunoprecipitates. Two protein fractions were obtained by extraction in a hypotonic medium and by detergent treatment of the residual pellet. Three distinctly different phosphatase activities were discerned, nucleoside diphosphatase (EC 3.6.1.6.), acid phosphatase (EC 3.1.3.2.) and alkaline phosphatase (EC 3.1.3.1.).

The nucleoside diphosphatase activity, which was confined to one antigen, was present in both water soluble and detergent extracts and at roughly the same concentration in eggs and plutei. By means of a monospecific antiserum the immunological identity of this antigen was established in all instances.

The acid phosphatase activity, which was displayed by ten detergent extracted antigens in eggs, was only found in five detergent extracted antigens in plutei. This decrease in number of enzyme active antigens was also reflected by a general decrease in activity as assessed by quantitative determinations. Furthermore, by means of absorbed antisera it was established that two or three of the acid phosphatase active antigens were “egg specific.” Another acid phosphatase active antigen, which was common to both developmental stages, was investigated by a monospecific antiserum. While this antigen was found in both soluble fractions, it was only enzymatically active when extracted with detergent.

Alkaline phosphatase active antigens were only found in the detergent extract of plutei. However, immunoprecipitates with this activity appeared both with antiserum against unfertilized eggs and with antiserum against plutei. This suggests that the egg contained the antigens in an enzymatically inactive form.
Reproductive performance of male and female phenotypes in three sex chromosomal genotypes (XX, XY, YY) in the killifish, Oryzias latipes
Authors: Fineman Robert , Hamilton James , Chase Gary
Published: June 2005

The present study investigates the juvenile and adult reproductive performance of Japanese killifish, Oryzias latipes, which were successfully sex‐reversed by feeding them male or female sex hormones during the fry stage. Sexual maturation of these laboratory grown fish of three known genotypes (XX, XY, YY) occurred earliest in untreated genotypes, next in genotypes treated with male hormone (methyl testosterone) and female hormone (estrone), respectively. The delay in sexual maturation caused by early exogenous, sex‐hormone treatment may represent a disturbance in the delicate neural‐gonadal axis. However, the degree of response was also strongly influenced by the animal's sex chromosomal genotype. XX fish, normally phenotypic females, were affected more by the male hormone than by the female hormone. XY and YY fish, normally phenotypic males, were delayed more by the female hormone than by the male hormone. This specific sex hormonesex genotype interaction also influenced adult reproductive performance (sperm or egg production). Differences in the metabolism of male and female sex hormones by the XX, XY and YY fish are probably responsible for these interesting findings.
Regeneration of the retina in the adult newt, Triturus cristatus, following surgical division of the eye by a limbal incision
Authors: Levine Robert
Published: June 2005

The regeneration of a retina in adult Triturus cristatus, following surgical division of the eye by a limbal incision, was studied. In agreement with recent reports, it was found that the regenerating retina is derived from two sources; the retinal pigment epithelium and the pars ciliaris retinae. However, following a limbal incision, most of the retina appears to be derived from the retinal pigment epithelium in the posterior part of the eye.

An unexpected finding of this study was that large cyst‐like spaces form in the fundal region of the eye, between the regenerating retina and the retinal pigment epithelium. These spaces appear between five and eight days postoperative and persist long enough (until 25 to 30 days post‐operative) to disrupt the fundal portion of the regenerating retina and to cause it to lag behind the rest of the regenerate, in its development.

The relationship of these observations to the genesis of positional markers in the regenerating retina is discussed.
Morphology and kinetics of spermatogenesis in Xenopus laevis
Authors: Kalt Marvin R.
Published: June 2005

The light microscopic characteristics of spermatogenic stages of the germ cell line in the anuran, Xenopus laevis, have been described as they appear in both nuclear squash preparations and plastic embedded thick sections of intact testes. Tritiated thymidine autoradiography was employed to unequivocally identify stages. Using this methodology, it was determined that the premeiotic DNA synthetic period occurs in a cell which is morphologically indistinguishable from a late secondary spermatogonial cell. In addition, kinetic studies with tritiated thymidine were employed to determine the duration of meiotic prophase and spermiogenesis in Xenopus. Results indicate that at 18°C, the most rapidly maturing cells in the testis spend four days in leptotene, six days in zygotene, twelve days in pachytene, one day in diplotene, one day in meiotic division, and twelve days in spermiogenesis. An estimate for the duration of the premeiotic S stage was indirectly calculated from combined data to yield a value of six to seven days. Pooled spermatocyte counts measuring the frequency of occurrence of individual stages produced results which correlated closely with estimates obtained by tritiated thymidine labelling. Individual counts, however, show wide variations between testes from single animals and between testes from different animals, whether sacrificed together or at different times of the year. Nevertheless, in all cases, both morphology and labelling patterns indicate that spermatogenesis is continuously active. The variation observed in individual testes appears to be the result of waves of non‐random entry of spermatogonial stem cells into the population of cells irreversibly committed to differentiation.
In vivo and in vitro fertilization of hamster, rat and mouse eggs after treatment with anti‐hamster ovary antiserum
Authors: Tsunoda Y. , Chang M. C.
Published: June 2005

Rabbit antiserum against hamster ovary was examined on agargel diffusion plates against several hamster tissues, and also against rat and mouse ovarian extracts. Unabsorbed anti‐hamster ovary antiserum showed eight to nine precipitin bands for hamster ovary and four to eight bands for other tissue extracts, but no bands against sperm antigens. Anti‐hamster ovary antiserum also showed three to four bands for rat and one to two bands for mouse ovarian extracts.

The present experiments confirmed previous reports for the hamster and mouse that treatment of eggs with anti‐ovary antiserum blocked in vitro fertilization and that the extent of the inhibition was related to the formation of a precipitate on the zona pellucida.

A single injection of anti‐hamster ovary antiserum inhibited fertilization in mice but not in rats. In vitro fertilization of mouse eggs was also inhibited in the presence of such antiserum.
Inhibition of early postimplantation development of cultured mouse embryos by bromodeoxyuridine
Authors: Spindle Akiko I.
Published: June 2005

Mouse embryos were treated with 5‐bromodeoxyuridine (BrdUrd) for 24 hours at various preimplantation stages to determine its effect on early postimplantation development. The inhibitory effect of BrdUrd (10−7 to 10−6 M) on trophoblast outgrowth and inner cell mass (ICM) development was least severe when embryos were treated at the 2‐cell stage and was most severe when they were treated at the morula stage. When embryos were treated at the blastocyst stage, the inhibitory effect on trophoblast outgrowth decreased, but that on ICM development remained severe. The severity of inhibition, particularly that on ICM development, appeared to be related to decreased cell numbers in BrdUrd‐treated embryos. However, increasing the cell number by aggregating two ICM's isolated from BrdUrd‐treated blastocysts did not increase their chance of survival or of forming two primary germ layers. This indicates that the decrease in cell numbers alone is not the cause of the failure of BrdUrd‐treated embryos to develop.

The mechanism of BrdUrd inhibition was studied by adding thymidine or deoxycytidine during BrdUrd treatments. A 10‐fold excess of thymidine completely protected embryos from the inhibitory effect of BrdUrd. A 10‐fold excess of deoxycytidine was less effective. Autoradiography indicated that both thymidine and deoxycytidine protected embryos by interfering with the incorporation of BrdUrd into the DNA.
Phylogenic distribution of limb regeneration capacity in adult Amphibia
Authors: Scadding Steven R.
Published: June 2005

Limb regeneration was studied in 13 adult amphibian species in which regeneration had not previously been investigated. Limb regeneration was not exhibited by four anuran species: Pseudacris triseriata, Hyla squirilla, Hyla crucifer, and Bufo quercicus. Among the adult urodeles studied, normal regeneration was observed in five species: Ambystoma laterale, another Ambystoma jeffersonianum complex species, Eurycea bislineata, Plethodon cinereus, and Plethodon glutinosus. Limb regeneration was absent or heteromorphic in individuals of Siren intermedia and Ambystoma maculatum. Regeneration was not exhibited at all by adult Necturus maculosus, and Ambystoma tigrinum. The phylogenic distribution of limb regeneration capacity, in the 41 species of amphibians for which information is presently available, is reviewed and discussed.
Cell proliferation and renewal in the small intestinal epithelium of metamorphosing and adult Xenopus laevis
Authors: McAvoy J. W. , Dixon K. E.
Published: June 2005

Intestinal folds of adult Xenopus laevis are formed by the proliferation of groups of cells in the tadpole epithelium at metamorphosis. As the folds increase in number and in height, mitoses become confined to the troughs and a gradient of decreasing mitotic activity from troughs to crests is formed. This pattern of cell proliferation was confirmed in autoradiographic studies with [3H]thymidine. Migration of cells from the fold troughs to the fold crests was also demonstrated by thymidine autoradiography and the epithelium renewal time was approximately 16 days. Thus cell proliferation and cell specialisation in the small intestinal epithelium of adult X. laevis are inversely correlated.
Spermiogenesis of Nautilus pompilius. I. General survey
Authors: Arnold John M. , Williams‐Arnold Lois D.
Published: June 2005

Differentiation of the spermatids, from secondary spermatocytes to mature spermatozoa in the spermatophores, is described for Nautilus pompilius. Early in development the spermatids have large cytoplasmic bridges which connect groups of cells which remain linked even when the residual cytoplasm is shed. The nucleus undergoes considerable elongation and the nuclear envelope loses its cisterna except in the centriolar fossa and adjacent to the acrosome. Condensation of the chromatin involves formation of dense sheets which run parallel to the long axis of the nucleus and eventually fuse to make a uniformly dense structure. The mitochondria migrate to one pole of the secondary spermatocyte where they apparently fuse to make two large mitochondria which elongate and eventually lie in grooves the whole length of the cylindrical nucleus. The centrioles are composed of nine sets of doublet microtubules and both migrate into the centriolar fossa. A massive manchette is formed which has extensive cross linked microtubules. The acrosome appears to arise from part of the Golgi apparatus and is a complex conical structure at the apex of the mature spermatozoan. The residual cytoplasm is shed by fusion of vesicles apparently derived from the nuclear envelope. Massive amounts of glycogen appear around the head in late spermiogenesis. Proximally, the flagellum has a sheath outside the microtubules which distally breaks up into nine coarse accessory fibers and further distally disappears. Nautilus sperm morphology is compared with the ultrastructure of other cephalopod spermatozoa and it is speculated that the differences found are greater than might be expected if the mechanisms of sperm transfer and fertilization were the only controlling forces determining the evolution of spermatozoan ultrastructure.
Respiratory exchange and transport of oxygen in Nautilus pompilius
Authors: Johansen K. , Redmond J. R. , Bourne G. B.
Published: June 2005

Respiratory exchange of oxygen and the role of the hemocyanin‐containing blood in gas transport have been studied in the cephalopod Nautilus pompilius.

Nautilu has a blood O2 capacity of 2.30 ± 0.57 vol%. The oxygen affinity is high compared to that of other cephalopods, P50 being 16.9 mmHg at pH 7.45 and 18°C. The n‐value (Hill coefficient) is 2.7 under those conditions. The Bohr factor, Ø, is low (i.e. −0.20). The temperature sensitivity, expressed by Δ, = −9.8 Kcal·MolHCY−1.

Average values for circulating blood Po2 are 99.2 (± 31.7 mmHg SD) for arterial and 20.4 (± 12.9 mmHg) for venous blood. Arterial blood is fully O2 saturated while the average venous O2 saturation is about 65%.

Direct measurements of ventilation average 296 ml·kg−1·min−1 while breathing rates vary between 40–60 min−1 at 18–20°C. Breathing rates and ventilation increase during locomotor activity and exposure to hypoxic water.

The results are compared and analysed with available data for other cephalopods. Nautilus, one species of Octopus and the squid Loligo show ascending transport efficiency for O2 correlated with increasing metabolic rates.
The effects of lumicolchicine, colchicine and vinblastine on pigment migration in fish chromatophores
Authors: Obika Masataka , Turner William A. , Negishi Sumiko , Menter David G. , Tchen T. T. , Taylor John D.
Published: June 2005

The effects of lumicolchicine, colchicine, vinblastine and cold temperature on the pigment migration in melanophores and xanthophores of Fundulus heteroclitusand Oryzias latipeswere examined by light and electron microscopy. Xanthophores of both species which contain numerous microfila‐ments and a poorly developed microtubule system were extremely sensitive to the alkaloids. Lumicolchicine and colchicine induced irreversible dispersion while vinblastine caused permanent aggregation of the pigments. Treatment in lumicolchicine or colchicine at 5 mM for 60 minutes did not disrupt micro‐tubules of melanophores to an appreciable degree, however, melanosome aggre‐gation was partially inhibited by these drugs in Oryzias. When melanophores were kept in the cold in the presence of colchicine at 1 mM, almost all micro‐tubules were disrupted and their repolymerization at room temperature was nearly completely inhibited by colchicine. These melanophores lacking in mi‐crotubules responded to epinephrine with slow aggregation. Vinblastine at 0.1 mM induced partial aggregation of melanosomes and disruption of micro‐tubules but most melanophores were still able to respond with pigment migra‐tion. Vinblastine at 1 mM made all melanophores punctate and immobile. Large vinblastine‐induced crystals were frequently seen in the dendritic proc‐esses. The results of the present investigation suggest that cytoplasmic micro‐tubules in fish melanophores facilitate melanosome migration only in di‐rectional orientation and appear not to be responsible for the motive force.
Inositol pentaphosphate in fish red blood cells
Authors: Borgese Thomas A. , Nagel Ronald L.
Published: June 2005

Inositol pentaphosphate (IP5) has long been characteristic of avian erythrocytes. We now report that this compound is also present in the red cells of two species of elasmobranch fishes, Squalus acanthias (spiny dogfish) and Narcacion nobiliana (torpedo ray). The mean concentration of IP5 is 0.36 and 0.24 micromoles per ml of red cells respectively. ATP is the major organic phosphate in both fishes. 2,3‐diphosphoglycerate is absent and GTP levels correspond approximately to the levels of IP5.