bluuebunny/crossref_metadata_2025 huggingface dataset:
Mating refusal in Musca domestica: Effects of repeated mating and decerebration upon frequency and duration of copulation
Authors: Leopold R. A. , Terranova A. C. , Swilley E. M.
Published: June 2005

The loss of sexual receptivity displayed by once‐mated female house flies, Musca domestica L., was investigated by repeatedly mating males to deplete the accessory secretion responsible for inducing this behavior. With each successive mating, there was a step‐wise increase in the amount of time spent in copulo and in the number of females remating that were first crossed with previously mated males. Mating pairs containing males that had copulated three times before remained in copulo about twice as long as pairs containing virgin males. The remating of females initially crossed with virgin males was 3% as compared to 21% for those females crossed with males that had mated three times previously. These phenomena are apparently related to the titer of male accessory secretion reaching the receptor site(s) in the female that induce mating refusal behavior. The brain of the female apears to have some control over the loss of mating receptivity since mating inhibition was not displayed by females that had been decapitated or had their brains destroyed.
Studies on hydroid differentiation. VI. Regulation of hydranth formation in Podocoryne carnea
Authors: Braverman Max
Published: June 2005

Removing the sole hydranth from young slide grown colonies of the marine hydroid Podocoryne carnea stimulates an increase in the number of hydranths subsequently formed, compared to fed controls. If controls and experimentals are both starved, both show increased hydranth formation but the colonies without hydranths increase hydranth numbers sooner than do the starved controls. Hydranth formation is discontinuous under these experimental conditions as it is in unoperated growing colonies during the first 20 days of growth.

When hydranths are removed from one half of each of a number of two week old colonies, stolon growth continues on the operated side at the same rate as on the unoperated side, indicating that nutriment is equitably distributed in the stolon system of the colony. Twice as many new hydranths are formed, however, on the operated side as on the control side. This experiment appears satisfactorily to control for the immediate starvation attendant upon hydranth removal, thus indicating that the location and therefore number of new hydranths in growing colonies of Podocoryne carnea is regulated by hydranths mediated feedback.

Comparison of the age of stolon on which hydranths form with what would be expected were this distribution random, indicates a strong skew to stolon three and four days old. Whether this is an additional developmental stricture or a consequence of hydranth feedback can not now be determined.
Cytogenetic analysis of pig oocytes matured in vitro
Authors: McGaughey R. W. , Polge C.
Published: June 2005

Primary oocytes from the ovaries of prepubertal pigs were stimulated to undergo maturation by removing them from small follicles and incubating them in a defined culture medium for various periods of time. The cultured oocytes were air‐dried and their chromosomes examined for the stage of meiosis and for the presence of abnormalities. Of 107 oocytes recovered after 26–27.5 hours of culture 41% were at diakinesis‐metaphase I and 2% were at telophase I. Of 96 oocytes recovered after 36–37 hours of culture 46% were at diakinesis‐metaphase I while only 14% were at metaphase II. These observations suggest that the oocytes were delayed at diakinesis‐metaphase I, since it has been shown previously that at 36–37.25 hours after HCG injection only 23% of oocytes are at metaphase I and 45% are at metaphase II in vivo. When recovered after 42.5–55 hours of culture 128 of 232 oocytes (55%) had reached metaphase II.

Of 56 cultured oocytes whose chromosomes were analysed at metaphase I, only one exhibited a chromosomal aberration (19 bivalents plus three fragments) and one oocyte contained 18 bivalents plus two monovalents.

Of 123 oocytes analysed at anaphase I, telophase I and metaphase II, 33 (27%) exhibited such chromosomal abnormalities as heteroploidy, fragments, chromosomal bridges, tripolar spindles and lagging chromosomes. In addition 31% of 128 oocytes at metaphase II displayed degenerate chromosomes. Therefore, of 232 immature oocytes cultured for 42.5–55 hours only about 20% could be regarded as chromosomally normal, mature secondary oocytes.

The delay at diakinesis‐metaphase I may be related to a failure of the supporting granulosa cells to supply some substance, possibly an energy source, required by the oocytes. It is suggested that during a delay at diakinesis‐metaphase I, the chromosomes of pig oocytes which failed to divide, may have become “sticky,” leading to the chromosomal aberrations observed at subsequent stages of meiosis.
Chromosome abnormalities of early rabbit embryos
Authors: Hofsaess F. R. , Meacham T. N.
Published: June 2005

Blastocysts recovered six days after fertilization from five California and four Dutch‐Belted does were used to study the chromosome aberrations of early rabbit embryos. The nine does had a mean ovulation rate of 8.8 ± 0.7 (range 7 to 14). On the basis of corpora lutea counts, 95% of the embryos were recovered. Anomalies were found in nine of the 75 embryos recovered; there being two cases of hypoploidy (2n = 43), four cases of double hypoploidy (2n = 42), and three cases of mosaicism. In addition to the chromosomally abnormal embryos, three embryos could not be cultured successfully and appeared to be degenerating.
Neurosecretory activity and protease synthesis in relation to feeding in Melanoplus sanguinipes (Fab.)
Authors: Dogra G. S. , Gillott C.
Published: June 2005

Virgin females of Melanoplus sanguinipes were starved for three days from emergence and then provided with food for various periods of time, ranging from five minutes to 72 hours. The temporal sequence of changes in neurosecretory activity, blood protein level and gut protease activity was investigated.

The starved insect has a neurosecretory system loaded with stainable product. Feeding, however, promotes a massive release of this material within 20 to 40 minutes. A significant increase in the synthetic activity of the neurosecretory cells (measured as 3H‐L‐cystine incorporation) does not begin until about two hours after food intake. Five or six blood protein bands can be separated electrophoretically, of which 2 and 3 are always present in relatively high concentrations. They are also the most variable, the changes in total blood protein level being almost entirely a reflection of the changes in these two. the blood protein level being almost entirely a reflection of the changes in these two. The blood protein level decreases during the first 12 hours of feeding (from 1.94 to 1.07 g/100 ml) but increases rapidly over the next 60 hours to reach a value of almost 4 g/100 ml. Total protease activity (crop + midgut lumen + caeca) increases shortly after feeding has begun and after four hours is significantly greater than in the three‐day starved female. The activity continues to rise until it is about 2.5 × the starvation level after 72 hours.

It is suggested that feeding stimulates the synthesis and release of neurosecretory material. The correlation between the rapid release of neurosecretion and early increase in protease activity is consistent with the hypothesis that the hormone acts directly upon the midgut epithelium stimulating protease synthesis. Furthermore the decrease in the level of blood protein for the first 12 hours after feeding could mean that it is being utilised in the production of digestive enzyme.
Ethanol induced notochord and spinal cord duplications in the embryo of the zebrafish, Brachydanio rerio
Authors: Laale Hans W.
Published: June 2005

Embryos of Brachydanio rerio, stage 10 (Hisaoka and Battle, '58) were exposed for 24 hours to graded concentrations of ethanol from 1 to 3%. Developmental abnormalities included defects of the eye, i.e., approximation, confluence and fusion of the optic cups mid‐ventrally; as well as duplications of notochord and spinal cord. Duplication of the spinal cord in the hind brain region has not been reported previously. The duplicatory effects are discussed and a mechanism of duplication by infolding roof plate material is proposed.
The stress response in the abundance of circulating leucocytes in the killifish, Fundulus heteroclitus III. The role of the adrenal cortex and a concluding discussion of the leucocyte‐stress syndrome
Authors: Pickford Grace E. , Srivastava Anil K. , Slicher Anna M. , Pang Peter K. T.
Published: June 2005

The response of intact Fundulus heteroclitus to intraperitoneal injections of ACTH at two hours post‐injection depends on the dose: leucopenia at low doses, leucocytosis at high doses. The two hour response to cortisol, at 5 μg/g, depends on the condition of the fish: leucocytosis in sexually mature or hypophysectomized fish, leucopenia in sexually regressed intact fish. At a physiological dose (0.025 μg/g) cortisol elicits a time sequence response in hypophysectomized recipients that is, initially, the reverse of that observed after coldshock: three minute leucocytosis, 15 minute leucopenia, and return to normal at 45 minutes. Leucocytosis emerges at two hours. Pretreatment with Metopirone for five to six days in the aquarium water is not well tolerated. Such treatment effectively blocks all phases of the cold‐shock response. Pretreatment for two days was tolerated and, in such fish, injection of epinephrine (1 μg/g) elicits both three minute and 30–60 minute leucopenia, but the leucocytic phases are blocked.

A tentative interpretation of the cold‐shock sequence is proposed on the assumption that catecholamines (presumably epinephrine) are leucopenic and that cortisol is leucocytic.
Multiple forms of tyrosinase in rodents and lagomorphs with special reference to their genetic control in mice
Authors: Holstein Thomas J. , Quevedo Walter C. , Burnett Jean B.
Published: June 2005

Polyacrylamide gel electropherograms of extracts of pigmented hair bulbs from rodents and lagomorphs indicate that tyrosinase exists in multiple molecular forms. Allelic substitutions at the a, b, c, d, and p color loci in mice reveal that the multiple forms of tyrosinase are subject to complex genetic influences. Depending upon genic constitution, a maximum of three electrophoretically‐separable forms of tyrosinase (T1 = 80,000 m. w.; T2 = 62,000 m. w.; T3 = 66,000 m. w.) can be visualized by incubation of the polyacrylamide gels in L‐DOPA. In certain genotypes of mice, T1, T2, and T3 are either greatly reduced in activity or absent. Urea, SDS, and EDTA fail to dissociate tyrosinase suggesting that the multiple molecular forms of tyrosinase are not simple aggregates of monomeric subunits stabilized by non‐covalent bonds.

Tyrosinase corresponding in mobility to the T1 of mice is also found in hair bulb extracts from black rats, black rabbits, gerbils and golden Syrian hamsters. The T2 and T3 components are distinct in the black rat but are represented by a single “T2‐T3” band in the gerbil, hamster and rabbit. An additional T0 band is found in the black rat. Available evidence suggests that T1 of comparable electrophoretic mobility is widely distributed in mammals and may be an additional indication of an underlying broad homology of pigmentary genes. At present, it is not certain whether the multiple forms of tyrosinase are “true” isozymes or a single enzymic moiety bound to structural components of the melanosomal matrix.
Distribution and development of glutamine synthetase in the embryonic cerebral hemisphere
Authors: Piddington R.
Published: June 2005

Glutamine synthetase (GS) activity is preferentially localized in a distinct cell mass, the ectostriatum, in cerebral hemispheres of late chick embryos. GS activities rise in the ectostriatum coincident with the growth of this prominent nucleus. GS development in the ectostriatum may be controlled by normal increases of 11β‐hydroxyl corticosteroids in late embryonic serum. It is clear in any case that GS activities in this area of the hemisphere are susceptible to precocious induction by these steroids in vitro. The significance of GS localization in the ectostriatum is discussed in terms of the possible normal roles for this enzyme in nervous tissue.
The fine structure of the retina in the newt, Triturus viridescens
Authors: Keefe J. Richard
Published: June 2005

The normal adult retina of the North American Urodele, Triturus viridescens, has been studied with the electron microscope. Three basic types of photoreceptors are observed: rods, possibly distinguishable as either red or green rods, single cones, and double cones. The photoreceptors differ from those reported in other amphibia in that: (1) none of photoreceptors contain an oil droplet; (2) all photoreceptors possess an enlarged paraboloid, and, (3) the double cones consist of two complete photoreceptors, a principal cone member and an accessory cone member. The two members are closely related to one another along the length of the inner segment through a clasping of the principal member within cytoplasmic expansions of the accessory member. The principal member inner segment bears strong resemblance to the single cone while the accessory member inner segment is rod‐like in nature.

The sustentacular elements of this avascular retina display a diversity of scleral processes. The presence of specific collar‐like glial ensheathments of the photoreceptors at the external limiting membrane contrasts with the extensive interreceptor contacts between all photoreceptor elements throughout the outer nuclear layer. The synaptic bases are characterized by the presence of three types of specific contact sites: (1) interreceptor contacts among all receptor bases; (2) clusters of fine horizontal cell dendrites penetrate the receptor base and terminate in a superficial spray of typical axodendritic synapses; (3) prominent bipolar dendrites enter within the horizontal cell processes terminating in the typical retinal ribbon synapse.

The significance of these observations are discussed with respect to the origin of the amphibian double cone, the metabolic support of the retinal, and the potential integration among the receptor cells.
Hormonal regulation of RNA synthesis by mouse mammary gland in vitro
Authors: El‐Darwish I. , Rivera E. M.
Published: June 2005

Explants of mouse mammary glands were cultured for one to five days in chemically‐defined medium containing various combinations of insulin, corticosterone, and prolactin. The changes in RNA content and synthesis effected by the several hormone combinations were assessed after one, two, three, and five days of culture. Histological examination was also made to determine explant viability and secretory development.

Insulin was responsible for the initial stimulation of RNA synthesis, but its activity fell after the first day. Prolactin and insulin effected maximal accumulation of RNA on the second day, but the influence of these two hormones also declined by the third day unless corticosterone was also present. The hormones in the sequential order in which they manifest their activity on mammary RNA thus appear to be: insulin, prolactin, corticosterone.

The non‐parallel patterns of uridine incorporation and RNA accumulation suggest that the major fraction of hormone‐stimulated RNA is synthesized during the first two days and can be maintained by the appropriate hormonal milieu. The histological responses show that although insulin alone has an early effect on RNA synthesis, the subsequent secretory differentiation of the explants requires the further presence of prolactin and corticosterone.
In vitro culture of eggs and embryos of the viviparous paedogenetic gallmidge Heteropeza pygmaea
Authors: Went Dirk F.
Published: June 2005

Eggs and embryos of the viviparous paedogenetic gallmidge Heteropeza pygmaea can be cultivated in vitro throughout the entire period of egg follicle growth and embryonic development. During this process they increase in volume more than 100 times. The culture medium, consisting of hemolymph and fat body cells, is obtained from Z‐ray sterilized, full grown larvae of the same species. Embryonic development in this medium is essentially the same as it is in vivo.

If the fat body cells of the culture medium have been damaged during their explanation, the embryos on the culture show vacuoles in their yolk syncytium after some time and do no develop further. If all fat body cells in a preparation stay intact, some of the embryos develop completely, whereas the others dissolve. Intact fat body lobes can not be used for in vitro culture, because they generally show degeneration which prevents embryonic development.

The suitability of the culture method is discussed.
The relationship between corpuscles of Stannius and serum electrolyte regulation in killifish, Fundulus heteroclitus
Authors: Pang Peter K. T.
Published: June 2005

Corpuscles of Stannius were surgically removed from male killifish, Fundulus heteroclitus, acclimated to one third Long Island Sound sea water. Asthenia and kidney stone formation were observed. An increase in serum total and dialytic calcium, chloride and potassium and a decrease in serum sodium and inorganic phosphate were evident. No change in serum magnesium was observed. Injections of homogenates of codfish corpuscles of Stannius into intact male killifish adapted to fresh or sea water produced a significant decrease in serum total calcium in sea water fish only.
Function of the parathyroid gland of the snake, Thamnophis sirtalis
Authors: Clark Nancy B.
Published: June 2005

Garter snakes, Thamnophis sirtalis, have four parathyroid glands that are similar histologically to those of other reptiles. A high percentage of the animals also possess accessory parathyroid tissue. Complete parathyroidectomy of the snakes produced severe depression of serum calcium values, tetanic convulsions, and significant elevation of serum phosphate within several weeks of the operation. Administration of mammalian parathyroid extract to normal snakes had the opposite effects, elevating serum calcium and depressing serum phosphate concentrations. In contrast, mammalian calcitonin preparations did not significantly affect serum calcium or phosphate values.

The parathyroid glands of snakes thus function to maintain normal neuromuscular coordination by regulating blood calcium and phosphate concentrations.
Growth and metabolic effects of prolactin and growth hormone in the red‐spotted newt, Notophthalmus viridescens
Authors: Brown Patricia S. , Brown Stephen C.
Published: June 2005

Growth hormone, administered in doses of 4 and 20 μg every other day for five weeks, caused a significant increase in length and weight in the newt Notophthalmus (Triturus) viridescens. Prolactin, similarly administered in the same amounts, likewise increased body length, but failed to elicit a significant body weight increase. Prolactin also caused increased liver weight and liver carbohydrate while growth hormone was without significant effect on the liver. Four weeks of treatment with 4 μg GH/day or 4 μg prolactin/day was without effect on gonad size.
Effect of mammalian insulin on plasma glucose in the mud puppy (Necturus maculosus)
Authors: Copeland Danny L. , DeRoos Roger
Published: June 2005

The effect of mammalian insulin on plasma glucose levels was studied in the paedogenic urodele amphibian, Necturus maculosus. Blood was collected from a cannula implanted in the dorsal aorta via the gastric artery and plasma glucose was estimated by the glucose oxidase method. Plasma glucose levels of untreated animals were 31.6 ± 1.6 mg% at the completion of the operation and then declined to 14.1 ± 2.5 mg% on the third post‐operative day; the levels remained relatively stable from the third through the fifth day when sampling was terminated. Subsequent experiments began on the third post‐operative day. “Normal” plasma glucose levels were judged to be too low to demonstrate a statistically significant insulin effect and a glucose tolerance study was performed to elevate plasma glucose. Plasma glucose levels were 9.3 ± 1.6 mg% before glucose administration and were 68.8 ± 4.2 mg% at 30 minutes after the infusion via the cannula of 25 mg glucose per 100 gm body weight. Plasma glucose levels declined 52% at 3 hours, 75% at 6 hours, and to approximately the pre‐treatment levels at 24 hours after the infusion. The effect of insulin on the decay curve of infused glucose was determined. Control animals received glucose and the hormone‐free carrier; experimental animals received glucose and 10 IU insulin per 100 gm body weight. Plasma glucose levels were not significantly lower than those of the controls at 30 minutes after the infusion, but were significantly lower at all subsequent sampling times (3, 6, 9, 12, 24, 48 hours) and were less than 3 mg% from 12 through 48 hours; no hypoglycemic symptoms were noted even in animals without detectable plasma glucose. The data indicate that plasma glucose is not a required source of energy in the mud puppy.
The role of the lizard thyroid gland in tail regeneration
Authors: Turner James E. , Tipton Samuel R.
Published: June 2005

Hypothyroidism in Anolis carolinensis caused almost a two week delay in blastema formation and tail elongation was completely inhibited. Hormonal replacement therapy (L‐thyroxine) in hypothyroid lizards allowed for normal blastema formation as well as subsequent tail elongation.

Hyperthyroidism in Anolis initiated the early development and subsequently the early completion of blastema formation but had no significant effect on tail elongation.

Histological observations in the hypothyroid regenerates when compared with those receiving thyroxine replacement revealed that: (a) the inhibition of tail elongation was due to an inhibition of the outgrowth of the ependyma into the developing blastema; (b) although tail elongation was inhibited in hypothyroid lizards, many tissues within the blastema did differentiate along the same time course as those found in hormonal replacement regenerates and controls; thus, thyroxine apparently had little to do with tissue differentiation in these animals.

Hypophysectomy was found to delay blastema formation by one and one‐half weeks and to inhibit tail elongation in the same manner as was found in hypothyroid lizards. A dose response relationship was found to exist between certain levels of thyroxine (0.04 to 0.2 μg) and tail regeneration in hypophysectomized lizards. The intermediate dose of thyroxine (0.2 μg) produced a maximum response with respect to lizard tail elongation. A greater dose of thyroxine (1.0 μg) did not further augment the regeneration process and any greater dose would likely produce an inhibitory effect.
Cytochrome oxidase activity during amphibian development
Authors: Boell Edgar J. , D'Anna Tommaso , Greenfield Phyllis , Petrucci Delio
Published: June 2005

Changes in cytochrome oxidase (COX) activity during development have been determined in homogenates of embryos of five species of amphibia: Rana esculenta, Rana pipiens, Amblystoma punctatum, Bufo americanus, and Xenopus laevis. When inhibitory substances produced by skin are removed or compensated for by bovine serum albumin, COX increases several fold throughout the period of prefeeding development in all species studied. The increase is interpreted as synthesis of COX accompanying production of new mitochondria. The rate of increase is considerably greater after the tail bud stage has been reached and appears to be associated with a period of general protein synthesis reported by others. DPNH‐cytochrome‐c reductase activity and respiration of intact embryos have been determined in Rana pipiens for comparison with COX. The developmental changes in general parallel those of COX but at quantitatively different levels.
Relationship of genotype and degree of chimerism in coat color to sex ratios and gametogenesis in chimeric mice
Authors: Mullen R. J. , Whitten W. K.
Published: June 2005

Genotype and the degree of chimerism expressed in the coat color of chimeric (allophenic) mice were found to be related to the frequency of multicolored chimeras, the sex ratio, and the production of gametes. The sex ratios of 310 chimeric mice of various combinations of genotypes were studied. The male: female ratios varied from 1:1 to ratios approaching 3:1. Multicolored chimeras in which one genotype predominated (“unbalanced” genotypes) had normal sex ratios of 1:1 (19 ♂ ♂, 21 ♀ ♀ ) suggesting that sex was determined by the predominating component. Multicolored chimeras in which neither component predominated (“balanced” genotypes) had sex ratios approaching 3:1 (70 ♂ ♂, 31 ♀ ♀ ) suggesting that most sex chimeras (XX ⟷ XY) develop as phenotypic males. Regardless of genotype, solid colored chimeras had normal sex ratios. Only two hermaphrodites (0.65%) were observed.

A high incidence of gonadal mosaics which produced progeny with both parental genotypes and a relatively low incidence of possible sex chimeras which produced progeny with only one genotype occurred among multicolored females. A very low incidence of gonadal mosaics and a very high incidence of possible sex chimeras was found among males. These observations would be expected if most sex chimeras developed as phenotypic males.
Instability of the epithelial‐mesenchymal interaction in the eight‐day embryonic chick thyroid
Authors: Hilfer S. Robert , Stern Mark
Published: June 2005

By using cells from the eight‐day chick embryo to study epithelial‐mesodermal interaction in the thyroid we have confirmed the results previously reported for the mature cells of the 16‐day gland. The cells, which do not yet possess a canaliculate endoplasmic reticulum, fail to develop these channels in monolayer culture. After seven days of spreading, the membranes are as sparse as they were in the eight‐day embryo and closely resemble those in cells of the 16‐day gland after a week of spreading. This lack of organization is in sharp contrast to the elaborate system of interconnecting channels of the 16‐day gland or the eight‐day gland which has been in organ culture for seven to eight days.

Reaggregation of the eight‐day monolayers has revealed the necessity of cells from the thyroid capsule for normal differentiation. Young and mature epithelial cells give basically the same responses to fibroblasts from heterologous organs. In both cases, histogenesis is abnormal. Aggregates prepared with capsule of the young gland result in necrosis of spread eight‐day epithelial cells and cord formation by spread 16‐day epithelial cells. Cells from the capsule of the 16‐day thyroid, on the other hand, produce normal thyroid when combined with either the 8‐ or 16‐day epithelium.

The results are compared with those from investigations of the epithelial‐mesenchymal interaction in other organs.
Expression of paternal genes during embryogenesis in the viable interspecific hybrid amphibian embryo Rana pipiens ♀ × Rana palustris ♂. Electrophoretic analysis of five enzyme systems
Authors: Johnson Kurt E. , Chapman Verne M.
Published: June 2005

Genetic differences in enzyme electrophoretic mobility have been used to determine the time of expression of paternal genes during embryogenesis in the viable interspecific hybrid amphibian embryo Rana pipiens ♀ × R. palustris ♂. Maternal isozymes for lactate dehydrogenase (LDH), 6‐phosphogluconate dehydrogenase (6‐PGD), glutamate‐oxaloacetate transaminase (GOT), glucose phosphate isomerase (GPI), and malate dehydrogenase (MDH) persist in unfertilized eggs and one, two, and three day embryos. Paternal type bands for 6‐PGD, GOT, and GPI appear at four days of development, when embryos are late Stage 19 and early Stage 20. Paternal bands for LDH and MDH appear at five days of development, when embryos are late Stage 20. These results are discussed in terms of paternal gene expression and the genomic control of early amphibian development.
Development of the rat salivary glands. I. Accumulation of parotid gland DNase activity
Authors: Ball William D.
Published: June 2005

The parotid gland of the rat contains high levels of a secretory DNase with a substrate preference for native DNA, requirement for divalent cations (Mg+ +) and pH optimum at 7. 5. This enzyme appears not to be found in the submaxillary‐sublingual gland complex, which has only a low level of DNase activity with a contrasting substrate preference for denatured DNA. Neonatal submaxillary and parotid glands both contain a constant, low level of activity which is similar in magnitude to that of the adult submaxillary gland. DNase activity in the neonatal parotid begins to increase between 10‐ and 15‐days post‐partum and rises 10,000‐fold by 30‐days. The substrate preference of the low DNase activity present in the parotid gland prior to ten days was determined for newborn rats, and was found similar to the adult submaxillary rather than to the adult parotid enzyme, since the newborn extract preferentially hydrolyzed denatured DNA. These results support the working hypotheses; that the parotid gland DNase is not found in the other salivary glands and is thus a specific marker of parotid differentiation, and that the synthesis of this enzyme in the parotid gland does not begin until after ten days post‐partum.

The results obtained here are discussed in terms of the possible relationships between early tissue interactions in the embryonic gland rudiments and their later assumption of a cell‐specific pattern of protein synthesis, and these relationships are compared to those found in previous analyses of the embryonic pancreas (Rutter et al., '67a). It is suggested that the regulation of specific cytodifferentiation in the salivary glands may be basically different in mechanism than that of the pancreas.
In vitro induction of ovulation and oocyte maturation in Rana pipiens ovarian follicles: Effects of steroidal and nonsteroidal hormones
Authors: Schuetz Allen W.
Published: June 2005

Individual ovarian follicles of Rana pipiens respond to hormonal stimuli in vitro. The relative effectiveness of progesterone and gonadotrophic hormones in initiating ovulation and oocyte maturation were compared. Maturation of oocytes (>99%) with limited concomitant ovulation resulted following treatment of follicles with progesterone. Frog pituitary tissue was less effective than progesterone in stimulating maturation, but was more effective in producing ovulation. Neither ovulation nor maturation was stimulated in response to the mammalian gonadotrophic hormones (FSH, LTH, PMS, HCG) or mammalian growth hormone. Mammalian LH produced both ovulation and maturation; furthermore, no synergistic interaction with FSH was observed. Maturation did not occur in response to the gonadotrophic hormones without a concomitant, but not necessarily equivalent, induction of ovulation. Follicular responsiveness, particularly to gonadotrophic hormones, was affected by animal and seasonal variations. Structural changes (follicular membrane detachment from the oocyte) were observed in unovulated follicles treated with hormones. The structural alterations were closely correlated with the induction of oocyte maturation. These observations suggest that (1) the intrafollicular events leading to ovulation and maturation are not equally sensitive to pituitary and progesterone stimulation, (2) maturation and ovulation activities of gonadotrophins are probably inseparable, (3) responsiveness of follicles to specific gonadotrophins is not related to only their FSH or LH activity. These data are consistent with the hypothesis that gonadotrophins act indirectly via the follicular tissues to initiate the processes of ovulation and maturation.
Temporal effects of ovine luteinizing hormone and desoxycorticosterone acetate on maturation and ovulation of oocytes of the catfish, Heteropneustes fossils (Bloch): An In vivo and In vitro study
Authors: Goswami Shashi V. , Sundararaj Bangalore I.
Published: June 2005

Intramuscular administration of ovine luteinizing hormone (LH) or desoxycorticosterone acetate (DOCA) into gravid catfish, Heteropneustes fossilis, shows that LH is a much less efficient maturation‐inducing agent than DOCA. Maturational changes occur two hours earlier following DOCA injection than with LH. In the second experiment, ovarian pieces obtained from catfish one to eight hours following LH or DOCA injection were cultured in Wolf and Quimby medium without hormones for 11 to 4 hours respectively; the total duration between hormone injection and termination of culture was 12 hours in every case. Oocytes sampled from catfish two hours after DOCA injection or four hours after LH injection completed the process of maturation in vitro in the absence of hormones. Further, oocytes obtained from DOCA‐injected catfish three, four and five hours after treatment and cultured for nine, eight and seven hours respectively, exhibited maturational changes far more advanced than in the oocytes of the corresponding LH‐injected groups. In LH‐injected catfish maturational changes were observed two hours later than those in DOCA‐injected group. It is suggested that this two‐hour time lag, noticed in both the experiments, represents the duration necessary for LH to act on the catfish interrenal to build up the circulating titers of corticosteroids required for maturation and ovulation of oocytes. It is tentatively concluded that the terminal hormones which act on the catfish oocytes to induce maturation and ovulation are the corticosteroids.
Factors directing the expression of sympathetic nerve traits in cells of neural crest origin
Authors: Cohen Alan M.
Published: June 2005

It has been assumed that the phenotype expressed by a particular cell of neural crest origin is determined by the tissues comprising the final site of that crest cell. To test this premise as it applies to differentiation of sympathetic ganglioblasts, the future site of the primary sympathetic ganglia was ablated from embryonic axial trunks and the remaining tissues including the migrating crest cells were grown on chorioallantoic membranes of host chicks. Despite removal of the ultimate site of the primary sympathetic chains, catecholamine‐containing cells, identified by a fluorescent test, differentiated ectopically.

These results suggest that tissues along the migratory route rather than the tissues comprising the definitive site direct catecholamine synthesis in crest cells. To test this possibility, segments of neural tubes containing neural crest were grown alone or combined with somites on the chorioallantoic membrane. It was found that sympathoblast differentiation requires the presence of somitic mesoderm. In addition, ablation of the ventral neural tube drastically reduces the quantity of sympathetic nervous tissue formed in the presence of somites. Whether the ventral neural tube affects the crest cells directly or affects the capacity of the somites to influence crest cell differentiation is as yet undetermined. Control experiments indicate that mesoderm from other sources will not substitute for the somites in eliciting differentiation of sympathoblasts. These experiments support the hypothesis that neural crest cells give rise to sympathetic neurons in response to conditions imposed while the cells migrate ventrally.
Physiological responses of larval and postmetamorphic Rana pipiens to growth hormone and prolactin
Authors: Snyder Benjamin W. , Frye B. E.
Published: June 2005

Bovine prolactin stimulates growth of tadpoles, whereas bovine growth hormone stimulates growth of postmetamorphic frogs. The biochemical composition of liver, muscle, and fat body were examined to determine whether there were any changes in carbohydrate, protein, fat, or nucleic acids which might correlate significantly with the growth effects of the hormones in the two stages of development. In the frog, the major effect of growth hormone was to depress carbohydrate and lipid stores, with little or no effect on protein and nucleic acids in most experiments. Prolactin had similar but smaller effects on carbohydrate, and no effect on fat body lipid in the frog. In tadpoles prolactin suppressed muscle glycogen, but otherwise did not affect tissue composition. Growth hormone had no effects in the tadpole. Ways in which the interrelated developmental and metabolic effects of growth hormone and prolactin could increase the adaptive significance of distinct larval and postmetamorphic growth‐regulating hormones in the amphibians are discussed.
Histological observations on allografts and reciprocal xenografts in newts (Notophthalmus viridescens) and axolotls (Ambystoma mexicanum)
Authors: Taban Charles H. , Connelly Thomas G.
Published: June 2005

A histological study, involving autoradiography of tritiated thymidine labelled host: and graft, was performed in reciprocal skin grafts between Notophthalmus viridescens and Ambystoma mexicanum. The histoanatomical differences in the two types of skin appear to interfere in the rejection processes. The adepidermal membrane and dermal collagen, as well as the activity of the host epithelial cells, are stressed as factors playing a role in the rejection rate of the graft.
The effect of prolactin on the seasonal cyclicity of newt forelimb regeneration
Authors: Schauble Muriel K. , Tyler David B.
Published: June 2005

A cyclic seasonal variation in forelimb regeneration in the newt, Notophthalmus viridescens, was noted under controlled environmental conditions at 20°C in previous experiments. Regeneration was enhanced in the summer months and reached its maximum linear growth rate in late spring‐early summer. It was suggested that this variation might be due to hormonal influences.

The pituitary hormone prolactin was selected for study because it has been shown to support regeneration in hypophysectomized newts and to enhance regeneration in the intact newt, in the intact newt more effectively than growth hormone. Experiments in winter and summeri were performed to determine whether prolactin alone enhanced regeneration and what effect it might have on the seasonal variation in regeneration.

The results clearly show enhancement of regeneration by intraperitoneal injections of prolactin in both summer and winter. The hormone increases the rate of linear growth and initiates early finger differentiation. The increase in linear growth rate persists throughout the 90‐day observation period. Prolactin does not enhance regeneration beyond the spontaneous optimum regenerative period in late spring‐early summer noted in previous experiments. Prolactin eliminates the seasonal variation in regeneration, and it is possible that the seasonal cycles are due to changes in output of this hormone.
Trout intestinal alkaline phosphatases I. Some physical‐chemical characteristics
Authors: Whitmore Donald H. , Goldberg Erwin
Published: June 2005

Four electrophoretic zones of trout intestinal alkaline phosphatase are described on the basis of charge and molecular weight heterogeneity. Qualitative and quantitative differences in the intestinal phosphatase complement suggest three basic phenotypes, which are exemplified by the isozyme patterns of wild brook trout, hatchery brook trout, and lake trout.

The partially purified and separated trout phosphatase zones have been characterized physically and chemically. The data presented clearly place these enzymes in the category of the non‐specific alkaline phosphomonoesterases. In common with this group of enzymes, trout phosphatases catalyze the hydrolysis of a wide variety of phosphomonoesters and pyrophosphates, as well as transphosphorylation reactions.
Trout intestinal alkaline phosphatases. II. The effect of temperature upon enzymatic activity in vitro and in vivo
Authors: Whitmore Donald H. , Goldberg Erwin
Published: June 2005

Two fundamental physical properties of partially purified trout intestinal alkaline phosphatases which have been examined in detail are thermostability and activation energy. It has been clearly demonstrated that differences in thermostability exist between the trout isozymes, and that as a group they are more thermolabile than mammalian phosphatases. The activation energies of the two main trout phosphatase zones, however, are comparable to mammalian phosphatases.

Experiments on cold‐acclimation of hatchery brook trout suggest that a fundamental reorganization of the intestinal alkaline phosphatase complement occurs. There are drastic quantitative differences in the isozyme patterns of 4° C‐acclimated fish and those acclimated to 10° C or 15° C. The 4° isozyme complement has a lower activation energy in the range of 2° C−10° C than does the 10° C isozyme complement. This finding strongly suggests that there is a reconstruction of the phosphatase isozyme complement with cold‐acclimation. This is functionally significant in that it results in the production of enzymes better suited to the new thermal regime. Three mechanisms are discussed as possible regulators of this process.
Experimental demonstration of holokinetic chromosomes, and of differential “radiosensitivity” during oogenesis, in the grass mite, Siteroptes graminum (Reuter)
Authors: Cooper Ruth S.
Published: June 2005

Early cleavage stages, mature eggs and developing oocytes of the grass mite Siteroptes graminum (Reuter), formerly Pediculopsis graminum (Reuter), (2n = 6; males haploid), were irradiated to: (a) test the hypothesis that the chromosomes are not monokinetic, (b) determine whether the chromosomes respond differently to irradiation during oogenesis and cleavage, and (c) find out whether a special region on the chromosome is required for elaboration of its chromosomoid (Feulgen‐negative body otherwise resembling the chromosome) which is left on the equator during both the meiotic and early cleavage mitoses. Fixation occurred 1–27 hours after irradiation.

Chromosomal complements of more than 160 embryos (egg through 128 cell), and a few meiotic figures, were analyzed. Clusters of cells with decipherable chromosomal complements of 8–16 elements occurred frequently, and in especially favorable embryos karyotypes of all or nearly all the blastomeres could be analyzed. Many chromosomal fragments passed through at least three to five cleavage divisions in normal or nearly normal manner. Fragments which had come through one or both meiotic divisions behaved in blastomeres in a manner similar to those induced in cleavage stages. The chromosomes, therefore, are holo‐ or polykinetic in the classical sense. The tiniest fragments and very large translocations, however, tended to missegregate or to be eliminated.

Some fragments were observed en route to or at the poles in both meiotic divisions. However, aberrancies in chromosomal behavior were more frequent during the maturation divisions, especially anaphase and telophase I, than during cleavage mitoses.

Differential radiosensitivity was detected during the course of oogenesis, and between oogenesis and cleavage stages, the first known case in the class Arachnida. As earlier stages were irradiated, there was a trend in blastomeres toward fewer fragments, and far more normal and nearly normal karyotypes. Irradiation of cleavage stages yielded most fragments. Probable causes of this differential radiosensitivity are discussed.

In the few cases with well‐preserved, discrete chromosomoids the relative size of the chromosomoid and its associated chromosomal elements (including very small fragments) were correlated, and in several cases more than the diploid number of each was present. This suggests, but does not prove, that any part of the chromosome can elaborate chromosomoidal material.

Possible causes, other than restriction of the kinetochore, for aberrancies in chromosomal behavior during both somatic and meiotic mitoses are discussed. The more recent literature on holokinetic chromosomes is analyzed, and new speculations about differences between mono‐ and holokinetic chromosomes are made. Factors of importance in design of experiments to determine the location of kinetochores are discussed.
Inhibition of imaginal differentiation in Sarcophaga bullata by juvenile hormone
Authors: Bhaskaran G.
Published: June 2005

The effects of DL‐juvenile hormone on imaginal differentiation in Sarcophaga bullata were studied with particular reference to the tissues of the abdomen. The hormone was applied topically on the pupal cuticle at the time of eversion of the head. The development of the abdomen varied considerably but a majority of the animals showed morphological abnormalities and none emerged. Histological examination of the treated animals at different periods of adult development revealed that none of them had secreted a second pupal cuticle. The most severe morphogenetic effect observed was the inhibition of the spreading of the histoblast cells. Consequently the imaginal epidermis was not formed and cuticular structures xwere completely absent. The differential sensitivity of the various cell groups derived from the histoblasts and the genital disc to JH were reflected in their developmental behaviour and are described in detail. The most conspicuous cellular effect, however, appears to be the inhibition of differentiation. Hence the JH induced abnormalities show striking similarities to those induced by x‐irradiation as well as other inhibitory agents during the metamorphosis of higher Diptera and are probably related to the highly determinate state of the cells.
Isozyme patterns of lactate dehydrogenase, creatine phosphokinase, phosphoglucomutase and aldolase of guinea pig tissues during ontogeny
Authors: Prochazka B. , Wachsmuth E. D.
Published: June 2005

Quantitative changes in the isozyme patterns of lactate dehydrogenase, creatine phosphokinase, phosphoglucomutase and aldolase during the ontogeny of guinea pig heart muscle, skeletal muscle, kidney and liver were investigated simultaneously.

In nearly all organs these changes could be attributed to the increase of that subunit which was predominant in the adult tissue. The adult isozyme patterns of PGM and CPK appeared earlier than those of ALD and LDH.

The findings that the distributions are different for different isozymes, different tissues and different stages of development are discussed.
The role of antlers in the behaviour of red deer
Authors: Lincoln G. A.
Published: June 2005

The behaviour of red deer stags following antler casting, antler breakage, antler amputation and antler stunting was studied to establish the ways in which antlers normally function. It was found that after the loss of antlers, either naturally or artificially, individuals became less effective in competition with other stags, resulting in loss of social rank in the bachelor group and failure to secure hinds in the rut.

The observations indicate that antlers normally function as a weapon and guard in conflict between stags and allow animals to lock their heads together for fighting. Of equal importance is the visual effect of the antlers denoting status of the individual, allowing for domination without physical force. While the stags are living in the bachelor herds the antlers appear to be the principal status symbol. During the rutting season, additional display symbols and characteristics come into use, and it is the significance of these in intimidation which allows stags without antlers (hummels) to be successful in the rut. There is slight evidence to support the idea that the antlers function in attracting hinds.