bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of genetic and environmental effects using GEE and APM methods
Authors: Bull S. B. , Chapman N. H. , Greenwood C. M. T. , Darlington G. A.
Published: June 2005

Two analytic methods were used in the Problem 2 data set. First, generalized estimating equations (GEE) modelling was developed to adjust for familial correlation in regressions evaluating candidate genes and an environmental factor. Second, the affected‐pedigree‐member (APM) method was used to identify chromosomal regions of interest and linkage of candidate genes with disease affection status. The GEE method identified C5 (MG1) as important for the quantitative trait Q1 and the corresponding affection status DIS, but the APM method was only suggestive. The GEE method identified C2 (MG2) as important for Q2 but only marginally important for Q1 and not important for DIS. © 1995 Wiley‐Liss, Inc.
Statistical genetics of normal variation in family data for oligogenic diseases
Authors: Mahaney Michael C. , Jaquish Cashell E. , Comuzzie Anthony G.
Published: June 2005

A quadrivariate quantitative genetic analysis detected significant heritabilities for four simulated quantitative traits (Q1‐Q4) with additive genetic pleiotropy between traits Q1, Q2, and Q3. Using univariate segregation analysis, we tentatively detected five major loci: one each for Q2, Q3, and Q4 and two, at different maxima, for Q1. Bivariate one‐locus segregation analysis identified significant major locus pleiotropy for Q1, Q2, and Q3 only; and suggested identity between one of Q1's major genes and that for Q2, and between the second Q1 major gene and that for Q3. Patterns of linkage, supportive of inferences from the bivariate segregation analyses, were detected between three candidate genes and the major genes for Q1, Q2 and Q4. © 1995 Wiley‐Liss, Inc.
The influence of response bias on segregation and linkage analysis
Authors: Mitchell Braxton D. , Atwood Larry D. , Reinhart Laurie
Published: June 2005

Response bias in epidemiologic studies can occur if affected individuals are more (or less) likely to participate in a survey than their unaffected counterparts. To examine the effect of response bias in the context of a family study, we conducted segregation and linkage analysis in all 1,000 individuals in the Problem 2 data set, and in two different 65% samples: one sample consisting of 648 randomly selected individuals, and the other sample nonrandomly constructed so that individuals with high levels of Q1 were oversampled. In this simulation the ability to detect major genes for Q1‐Q4 in segregation analysis and to link these putative major genes to genetic markers in linkage analysis was not markedly different between the 65% random and the 65% enriched samples. © 1995 Wiley‐Liss, Inc.
Statistical properties of the allelic and genotypic transmission/disequilibrium test for multiallelic markers
Authors: Bickeböller Heike , Clerget‐Darpoux FrançOise
Published: June 2005

The transmission/disequilibrium test (TDT) is extended in two ways for a multiallelic marker: (1) to compare transmitted and nontransmitted alleles from a single heterozygous parent and (2) to compare genotypes formed by the two transmitted alleles and genotypes formed by the two nontransmitted alleles using the information on both parents, heterozygous or not, simultaneously. © 1995 Wiley‐Liss, Inc.
Computing conditional recombination probabilities given marker information
Authors: Miller Michael B.
Published: June 2005

When a parent is homozygous, it is not possible to determine directly whether offspring share an allele identical by descent (IBD) from that parent. However, an IBD probability can be computed using information from linked loci where the parent is heterozygous. To solve this problem for the phase‐known case, probability equations and a computer program were developed for efficient computation of conditional probabilities under a Sturt model of chiasma interference. Data are analyzed and contrasted with and without taking interference into account. The effect of failing to account for interference is very small, but the computational cost is also small. © 1995 Wiley‐Liss, Inc.
Studies on the development of mouse embryos in vitro. I. The effect of osmolarity and hydrogen ion concentration
Authors: Brinster Ralph L.
Published: June 2005

Several thousand two‐cell mouse ova were cultivated in vitro, and the effect on development of changing the osmolarity and hydrogen ion concentration of the medium was examined. Statistical experimental design techniques were employed throughout the experiments in order to make the most efficient use of the material available. The two‐cell ova were cultivated for three days, and the percentage which developed into normal blastocysts was used as a measure of the treatment effect.

Changing the osmolarity of the medium had a marked effect on the number of blastocysts developing from two‐cell mouse ova. Blastocysts developed in media with osmolarities ranging between 0.2002 and 0.3542 osmols. The optimum osmolarity for the development of two‐cell mouse ova into blastocysts was 0.2760 osmols.

The hydrogen ion concentration of the culture medium also had an effect on the development of two‐cell mouse ova into blastocysts. Although blastocysts developed in media with pH's ranging from 5.87 to 7.78, the optimum pH appeared to be near 6.82.
Sperm penetration through the zona pellucida of the sheep egg
Authors: Dziuk P. J. , Dickmann Z.
Published: June 2005

Sheep eggs were obtained at appointed times from 4 to 16 hours after ovulation and examined for evidence of penetration by spermatozoa. The following observations were made: (1) The fertilizing spermatozoon makes a curved slit in the zona as a result of traversing it. The slit seems to be an open passage. (2) The sperm head of the ram has ventral‐dorsal asymmetry. The flat side of the sperm head always faces the vitellus as it passes through the zona. (3) A fine filament‐like structure was observed extending from the anterior tip of sperm heads embedded in the zona. (4) The site on the zona at which spermatozoa penetrate into the egg is random.
The duodenal progenitor population. I. Age related increase in the duration of the cryptal progenitor cycle
Authors: Thrasher J. D. , Greulich R. C.
Published: June 2005

The duodenal progenitor population has been investigated in four age groups of male Swiss albino mice, utilizing tritiated thymidine and autoradiography following sequential sacrifice of the experimental animals. Parameters evaluated in the different age groups included: (1) duration of the progenitor cycle and its component phases; (2) DNA‐synthetic index; and (3) mitotic index.

Analysis of the kinetics of metaphase labeling revealed that the mean duration of the entire cycle lengthens with age, whereas the mean duration of the DNA‐synthetic phase is constant (ca. 7.4 hours) irrespective of age. Estimates of the cycle duration based upon calculations from the DNA‐synthetic index also demonstrate an increase with age, although the absolute values derived in this manner do not agree with those based on metaphase labeling.

Determination of the cryptal DNA‐synthetic and mitotic indices disclosed a decrease in the percentage of labeled and/or mitotic cells with increasing age. Thus, the prolongation with age in mean progenitor cycle duration involves an increase in the average time which a duodenal progenitor cell spends in the interphase (G1) portion of the cycle.
The homolog of the pituitary‐adrenocortical axis in the teleost fish Tilapia mossambica
Authors: Basu Juthika , Nandi Jean , Bern Howard A.
Published: June 2005

The effects of hypophysectomy and of hormone treatments on the interrenal of Tilapia mossambica were studied, utilizing measurements of mean interrenal nuclear diameter as an index of interrenal function.

Hypophysectomy of Tilapia maintained in isotonic Ringer's solution resulted in a significant decrease in interrenal nuclear diameter after 21 days. This decrease was prevented by treatment of hypophysectomized fish with mammalian ACTH. Mammalian ACTH significantly increased the interrenal nuclear diameters of intact fish maintained in fresh water, but failed to do so in intact Tilapia kept in isotonic Ringer's solution.

Administration of cortisol acetate to intact Tilapia reduced the mean nuclear diameter of interrenal cells. The degree of response was both dose and time dependent. Administration of 0.04 mg/day of deoxycorticosterone acetate for 21 days also significantly reduced the mean interrenal nuclear diameter. Treatment with the same dose of DCA for only 14 days, or with a smaller dose for 21 days, failed to induce interrenal atrophy.

These results suggest that a pituitary‐interrenal axis, resembling the pituitary‐adrenocortical axis of mammals, exists in Tilapia mossambica.
The duodenal progenitor population. II. Age related changes in size and distribution
Authors: Thrasher J. D. , Greulich R. C.
Published: June 2005

Tritiated thymidine (H3‐T) autoradiography has been applied to the duodenal progenitor population (crypts of Lieberkühn) in four age groups of male Swiss albino mice to determine: (1) the size and distribution of the progenitor cell pool; and (2) to characterize the role of individual progenitor cells in previously reported age‐related alterations in the proliferative activity of the population.

The progenitor cells which incorporated H3‐T extended from the first cell below the crypto‐villal junction to the last cell (Paneth) at the cryptal base in each age group. However, the majority of labeled progenitor cells were restricted to the central region of the crypt, while a smaller number was found in both the upper and basal portions. Thus, the crypt wall was divided into three zones according to the incidence of labeled cells; (1) zone of minimum cell proliferation (upper region), (2) zone of maximum cell proliferation (central region), and (3) zone of Paneth cells (basal region). The labeling incidence of the maximum zone was 3–5 times that of the minimum or Paneth regions.

Comparison of the labeling incidence at the different ages revealed an age‐related decrease in the overall frequency of labeled cells throughout the crypt, and particularly in the maximum zone. Estimations of the progenitor cycle duration from the ratio of S‐phase duration to the DNA synthetic index revealed an increase in the progenitor cycle duration with age. It appears that the cycle duration increase, rather than a decrease in the size of the functional progenitor pool, may be the reason for theage‐related change in the proliferative activity.

The labeling frequency of progenitor cells was least (about 1%) at the cryptovillal junction and highest (about 50%) in the central region of the crypt. It is concluded that factors in the microenvironment of the duodenal epithelial cell population may be regulating the proliferative activity of the progenitorcells.
Comparative responses of regulative and determinate embryos to metabolic inhibitors
Authors: Markert Clement L. , Cowden Ronald R.
Published: June 2005

The developmental responses of embryos of the tunicate, Ascidia nigra, and the sea urchin, Lytechinus variegatus, to an assortment of antimetabolites was determined by microscopical observation of gross and cellular morphology and by cytochemical tests on sectioned embryos for DNA, RNA, and protein. Actinomycin D, puromycin, and analogs of amino acids and nucleic acid constitutents were all tested in sea water cultures of the two types of embryos, one determinate and the other regulative in developmental behavior. The response of these embryos suggests that the principal synthesis of ribosomes and proteins occurs abruptly at the onset of metamorphosis in Ascidia nigra embryos and more gradually and at earlier stages in Lytechinus embryos. RNA synthesized prior to gastrulation may be messenger RNA, but this RNA is probably not responsible for the determinate properties of ascidian blastomeres since these properties appear earlier, by the 4 to 8 cell stage. The regulative sea urchin embryos were somewhat more sensitive to the antimetabolites used but their responses were similar to those of ascidian embryos.
A comparative study of the responses of mammary tissues from several mammalian species to hormones in vitro
Authors: Barnawell Earl B.
Published: June 2005

Prelactating mammary tissues from five mammalian species (laboratory rat, guinea pig, hamster, rabbit, dog) were maintained in organ culture in the presence of insulin, corticoids and ovine prolactin (mammotropin — MH) and/or bovine growth hormone (somatotropin — STH). MH stimulated secretion in all but one species; however, any apparent secretory effect of STH could be accounted for by contamination with MH. Accordingly, these mammals did not demonstrate the interchangeability of MH and STH established for some mouse strains. There are species differences in mammary sensitivity to MH: dog and rabbit are most sensitive, hamster and rat are less sensitive, and guinea pig was unresponsive. No difference in response between Long‐Evans and Sprague‐Dawley rats was detected.

Mammary tissues from the dog, guinea pig and rabbit showed some ability to survive in the unsupplemented synthetic medium “199” whereas tissues from the other two species showed little or no viability. Supplementation of the medium with insulin results in improvement in survival of mammary tissues from all species. The further addition of corticosteroid (aldosterone, cortisol or corticosterone) leads to greater augmentation of survival in tissues from all five species, with some indication that the gluco‐corticoid principally characteristic of the species concerned was more effective than the others.
Growth and differentiation in hydra. I. The effect of temperature on sexual differentiation in hydra littoralis
Authors: Park Helen D. , Sharpless Norman E. , Ortmeyer Anne B.
Published: June 2005

Hydras cultured for long periods at constant temperature (23°, 21°, 18°, 15°, 10°, or 5°C) were exposed to a new, higher or lower temperature for four weeks.

It was found that at constant temperature, the percentage of hydras entering sexuality and the duration of the sexual periods decreased with decreasing temperature. There was no sexual differentiation at 5°.

No hydras became sexual within four weeks after a decrease in temperature.

The results of the temperature rise experiments show that, in general, the percentage of hydras entering sexuality depended on the absolute temperature change. The results indicate that this percentage also depended on the initial and final temperatures.

An hypothesis is presented, accounting for sexual differentiation in terms of a temperature effect on an initiator and an inhibitor.
The localization of α‐hydroxy acid oxidase in renal microbodies
Authors: Allen John M. , Beard Margaret E. , Kleinbergs Skaidrite
Published: June 2005

The enzymatic properties and cellular localization of α‐hydroxy acid oxidase have been studied in renal tissue of the rat. The enzyme was most active in the presence of D, L‐ α‐hydroxy valeric acid and D, L‐ α‐hydroxy butyric acid and was inactive in the presence of glycolic acid and D‐alanine. It appeared to have no co‐factor requirement. When subjected to electrophoresis in acrylamide gels, followed by cytochemical development, the enzyme was visualized as a major form accompanied by a minor component. The properties of the major electrophoretic form as determined by cytochemical reaction and densitometric scanning were similar to those determined by quantitative biochemical assay. When subjected to differential centrifugation and density equilibrium centrifugation, particles containing α‐hydroxy acid oxidase sedimented with particles containing D‐amino acid oxidase; α‐hydroxy acid oxidase, therefore, is associated with renal microbodies. The fact that α‐hydroxy acid oxidase transfers electrons to Nitro blue tetrazolium or to Tetra nitro blue tetrazolium made it possible to localize the enzyme by a light microscopic cytochemical procedure. The enzyme was found by this method to be localized predominantly in cells of the proximal tubule. It was present in particles approximately 0.5 μ to 1.0 μ in diameter mainly situated in the basal portions of these cells. These cytochemical preparations probably accurately reflect the cellular distribution of α‐hydroxy acid oxidase and, hence, of those microbodies which contain the enzyme.
Oxidative phosphorylation in the minute mutants of Drosophila
Authors: Farnsworth M. W.
Published: June 2005

Oxidative phosphorylation was studied in mitochondria isolated from whole 72‐hour larvae heterozygous for nine different Minute mutants with loci on the second and third chromosomes, i.e: M(2)12, M(2)1, M(2)173, M(2)z, M(3)w, M(3)124, M(3)B2, M(3)y and M(3)1. In all Minutes, oxidative phosphorylation was found to be abnormal in that phosphorylation was uncoupled from oxygen uptake to a greater extent as compared to controls. Differences with respect to respiration and/or phosphorylation were also evident between the Minutes themselves. The results strengthen the hypothesis that lesions in oxidative phosphorylation are associated with the Minute phenotype and demonstrate genetic control over this basic cellular process. In addition, if it is assumed that the Minutes are heterochromatic, as believed by many investigators, then the present study indicates a physiological function for heterochromatin.
Development, polarization and regeneration of the ventral iris cleft (Remnant of choroid fissure) and protractor lentis muscle in urodele eyes
Authors: Stone L. S.
Published: June 2005

Development of the protractor lentis muscle and the vestige of the choroid fissure, the ventral iris cleft, was studied in Amblystoma punctatum embryos, larvae and young adults. One hundred twenty‐three embryonic eyes in various stages of development were excised, rotated 180° and reimplanted to determine when in development the cleft and muscle become ventrally polarized. In Amblystoma, as the optic cup forms and the ventral region closes, the choroid fissure becomes a deep notch at the mid‐ventral rim of the cup. It remains as a cleft in the iris near the retina as the outgrowing iris obliterates the rest of the fissure. In Triturus v. viridescens the cleft becomes located in the middle of the ventral iris membrane some distance from the ora serrata. The protractor lentis muscle arises from mesenchyme cells at the inner surface of the cornea near the cleft which it enters. In A. punctatum, the polarity of the cleft and muscle is not yet established up to stage 29. From stages 29+ to 33, when the early optic cup is forming, their polarity is labile. Polarity is permanently established soon after at stage 34.

After complete ventral iridectomy the cleft reappeared in the regenerated iris. The muscle reappeared in some cases also. Retinal pigment cells locally regenerate the ventral iris and restore to it the capacity to replace a cleft which is similar to the vestigeal structure derived from the choroid fissure.

This is another example where dedifferentiated retinal pigment cells restore locally to regenerating tissue the ability to form special structures normal to that region.
Analysis of the vegetalizing action of tyrosine on the sea urchin embryo
Authors: Mastrangelo Molly Fudge
Published: June 2005

Vegetalization was produced in sea urchin embryos by treatment with D‐ and L‐p‐tyrosine, o‐tyrosine, and m‐tyrosine, for 2 to 6 hours during cleavage. Glycine was without effect on development; phenylalanine produced general effects represented by reduction of both animal and vegetal structures. The vegetalizing action of tyrosine was synergistic with that of lithium or dinitrophenol. However, unlike the latter compounds, tyrosine had no effect on respiratory rate of the embryos.

The uptake and the incorporation of algal hydrolysate‐C‐14 and leucine‐C‐14, added to the sea water medium, were lower in sea urchin embryos in the presence of tyrosine or phenylalanine than in untreated control embryos. Inhibition of incorporation caused by phenylalanine was about twice that by tyrosine, and it was postulated that the different effects of these substances on development are related to the degree of inhibition. Neither glycine nor lithium inhibited amino acid uptake.

When embryos were treated with tyrosine in the presence of a full complement of those free amino acids normally found in the egg, the vegetalizing effect of tyrosine was annulled. Since the sea urchin depends upon endogenous amino acids for protein synthesis during cleavage, it is suggested that in some way tyrosine limits the endogenous supply of amino acids available for synthesis of the proteins associated with animal structures by inhibiting their release from storage protein.
Origin of the hypoblast in Salmo. I. Does the blastodisc edge turn inward?
Authors: Ballard William W.
Published: June 2005

Nile blue sulfate stain spots printed upon the teleost blastodisc may penetrate to deep cells. Spots printed upon the periblast just outside the rim of the early blastodisc remain stationary, and when overridden by the spreading disc may transmit their stain to cells of its floor that come progressively in contact with them. Such spots do not give reliable evidence of invagination movements, or of a wheeling‐in of cells that lie inside the cellular envelope though close to the surface. Small spots printed upon the surface at the margin of the blastodisc do not necessarily disappear from the margin, and if they do they cannot subsequently be discovered in the interior. Patterns of chalk particles injected into the blastodisc for the purpose of demonstrating the origin of the hypoblast by a wheeling‐in movement of cells at the rim have produced no such evidence, but show a direct migration of originally internal cells toward the definitive somites. Conclusions drawn from the Salmo fate map and scheme of morphogenetic movements (Pasteels, '36) are not substantiated insofar as they pertain to the origin of the hypoblast and the behavior of cells at the blastodisc rim. There is no inturning of cells to produce the hypoblast, either at the axis or along the germ ring.
Histochemical localization of enzymes in the embryonic chick liver
Authors: Conklin James L.
Published: June 2005

Oxidative and hydrolytic enzymes were localized histochemically in the developing chick liver and in liver grown as chorioallantoic (CAM) transplants or as explants in organ culture.

In the in situ liver, parenchymal cells exhibited an increase in succinate (SDH) and a glycerophosphate (GDH) dehydrogenase activity and a decrease in NADP diaphorase (TPND) during development. NAD diaphorase (DPND) and nonspecific esterase (NSE) activity remained constantly high throughout the period studied. Within the stromal cells, DPND and NSE activity decreased and SDH, GDH and alkaline phosphatase (ALP) increased. The ALP activity of the sinusoidal cells appeared to increase coincident with a redistribution of TPND within the cytoplasm of the parenchymal cells.

In CAM transplants, the enzyme activity of all tissues was nearly the same as the five day liver even though the total age of the tissues was 15 days.

Liver explants exhibited enzyme activity similar in part to both the 5 and 15 day liver.

In both explants and transplants, ALP activity was highest in areas where the parenchymal‐sinusoidal relationship was maintained and absent in areas where the parenchyma and sinusoidal cells were not in contact.
Effects of mammalian hypophysial hormones, placental gonadotrophins, gonadal hormones, and adrenal corticosteroids on ovulation and spawning in hypophysectomized catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Goswami Shashi V.
Published: June 2005

Experiments were conducted to evaluate the effects of mammalian hypophysial hormones, placental gonadotrophins, gonadal hormones, and adrenal corticosteroids on ovulation and spawning in three‐day hypophysectomized gravid catfish. Of the hypophysial hormones tested (FSH, LH, LtH, STH, TSH, ACTH, and oxytocin), at various dose levels, LH alone consistently induced ovulation and spawning of eggs; administration of 5 mg/fish evoked the best response. The weak response obtained with FSH, STH, or TSH was not due to LH contamination. HCG at a dose level of 100 IU/fish induced ovulation and spawning, whereas in the case of PMS, doses of 250 IU/fish and above were equally effective. None of the gonadal hormones tested (estradiol, testosterone, and progesterone) evoked ovulation or spawning. All the adrenal corticosteroids tested (hydrocortisone, cortisone, and DOCA) proved to be powerful ovulating agents, DOCA (5 mg/fish) being the most effective. These findings indicate that in the catfish, LH and HCG as well as adrenal corticosteroids are effective in inducing ovulation and spawning in three‐day hypophysectomized gravid catfish. The possible mechanisms involved are discussed.
Reciprocal transplantation of eggs between rabbit and ferret
Authors: Chang M. C.
Published: June 2005

Thirty‐four 2–4 celled ferret eggs were transferred into Fallopian tubes of six 1‐day pseudopregnant rabbits. Two days later ten normal 8–12 celled eggs without mucin coat of 15 transferred to three rabbits were recovered from their tubes and uteri. Four days after transfer none of 19 eggs transferred to the other three rabbits were found, indicating disintegration and disappearance of early ferret eggs in the rabbit uterus.

Fifty‐one ferret morulae or blastocysts were transferred into tubes of eight pseudopregnant rabbits. Examined two or four days later, four eggs from tubes were normal and expanded blastocysts. Of 25 eggs from uteri, nine (36%) were expanded and normal but 16 (64%) were expanded and degenerating.

Fifty‐eight ferret morulae or blastocysts were transferred into uteri of six 4‐day pseudopregnant rabbits. Examined 2–4 days later all 45 recovered eggs were degenerated, showing incompatibility of ferret blastocysts in rabbit uteri.

When 25 1‐day rabbit eggs were transferred into ovarian capsules of three ferrets one and one‐half days after an ovulation inducing injection no cleavage was observed in the eight eggs recovered from tubes and uteri. From 54 rabbit morulae or blastocysts transferred into uteri of six 6‐day pseudopregnant ferrets, all 28 recovered eggs were degenerated and shrunken. No decidual reaction was observed either in rabbit or ferret endometrium.

It is concluded that ferret eggs can survive and develop if introduced into the tubes of the rabbit but not into the uterus, whereas rabbit eggs cannot survive if introduced into either the ferret tube or uterus.
Further studies on the induction of tolerance of skin homografts in rats
Authors: Silvers Willys K. , Billingham R. E.
Published: June 2005

With the BN → Lewis rat strain combination it has been shown that the median survival time of skin homografts on three‐day‐old hosts (10.0 ± 0.5 days) does not differ significantly from that of similar grafts on adult animals. This rapid attainment of immunologic maturity has provided the basis for a sensitive test for the induction of tolerance of skin homografts. The putative tolerance‐conferring stimulus is injected intravenously at birth and the hosts are challenged with donor strain skin three days later. With this system it has been found that whereas an inoculum of 100,000 bone marrow cells elicited weak sensitization, as evidenced by a significant curtailment of graft survival, increasing the dosage to one million or more cells induced tolerance, as shown by prolongation of graft survival. The proportion of hosts displaying tolerance and its degree, increased with the cell dosage. When test‐grafting with skin was delayed until the hosts were 50–60 days old, the minimal number of cells required to confer tolerance was seven million.

With the present assay it has been shown that the tolerance induced by low dosage cellular inocula wanes fairly rapidly, though the presence of a skin homograft from the third day onwards may prolong its duration.

A previous finding that, with the present strain combination, bone marrow cells are significantly superior to either spleen or lymph node cells in conferring tolerance of skin homografts has been confirmed. It has been shown that adult thymocytes are only capable of inducing feeble degrees of tolerance over a wide dosage range (5 ‐ 50 × 106) and that thymocytes from infant donors are ineffective.

Viable suspensions of epidermal cells and x‐irradiated or frozen‐thawed suspensions of bone marrow cells failed to confer tolerance, though it was induced fitfully by means of a microsomal lipoprotein extract of BN lymphoid tissue.

Finally, it was shown that the survival of BN test grafts on three‐day‐old Lewis hosts was significantly prolonged if they were born of Lewis mothers specifically presensitized against BN antigens. This constitutes evidence of a passive transfer of the isoantibodies responsible for the phenomenon of immunological enhancement.
A biochemical study of the growth of Drosophila melanogaster
Authors: Church Robert B. , Robertson Forbes W.
Published: June 2005

1. The growth of a wild strain of Drosophila melanogaster has been studied from the time of hatching from the egg to the adult. Wet and dry weights, protein and protein fractions, lipids, RNA and DNA have been determined at successive intervals. 2. All estimates have been carried out on animals grown axenically on defined medium. The medium has been shown to permit growth which is as fast as on live yeast medium when the larvae can burrow freely. 3. Insoluble protein and chitin nitrogen reach a maximum of about 70% total nitrogen in the late pupa, at which time the soluble nitrogen reaches its lowest level. The amino acid fraction reaches a maximum in the early third instar. 4. The water content declines from 70–75% of the live weight at the end of the first instar, rises to a maximum during the second instar and declines sharply to about 66% at the prepupal stage. 5. Total lipids represent an increasing proportion of body weight during larval growth, increasing from about 6% in young larvae to about 15% at pupation. 6. The curve of RNA increase follows the dry weight and protein curves during larval life. The ratio of RNA to protein declines during the first two instars. 7. The increase in DNA content follows a path similar to that of RNA. The RNA/DNA ratio reaches a maximum 24 hours after hatching from the egg, declines to about half this value by 84 hours, and remains more or less constant thereafter. 8. The rates of increase of protein, RNA and DNA during successive periods of larval life show striking differences. For protein the rate is high and increasing until about 36 hours after which it declines rapidly during the rest of larval life. For both nucleic acids the rate of increase falls to a minimum in the early third instar, about the time of the critical size, then increases during proliferation of the imaginal discs and finally declines at the end of larval life. 8. The data are compared with evidence from other strains of Drosophila and from other species of insect. In the latter case, it appears that all the Diptera, so far examined, follow a similar trend in the increase of the nucleic acids during growth. 9. RNA synthesis has been followed during development from egg to adult with the aid of pulse‐labeling and sucrose gradient analysis. Developmental stages differ in the amount of rapidly labeled high molecular weight material which is most evident in newly hatched larvae and in mid‐third instar larvae, at times when the rate of synthesis of total RNA is high.
A study of DNA synthesis during the transformation of the Iris into lens in the lentectomized newt
Authors: Eisenberg Sara , Yamada Tuneo
Published: June 2005

An autoradiographic study of the pattern of DNA synthesis in Wolffian lens regeneration of adult newt Triturus viridescens was carried out. Animals were injected with thymidine‐H3 at different stages of lens regeneration, and killed after different time intervals ranging between 2 hours to 15 days. The temporal pattern of incorporation and localization of labeled cells was studied with autoradiograms.

DNA synthesis, which is not detectable in the normal iris, is activated in the dorsal as well as in the ventral iris within five days after lens removal when the cells are still heavily pigmented. When the dorsal iris cells become depigmented, all depigmented cells show a high labeling frequency. Cessation of DNA synthesis is indicated immediately before the depigmented cells start to elongate and differentiate into fibers. At later stages of regeneration, when the regenerate is composed of fibers, lens epithelium, and stalk, DNA synthesis is limited to the latter two. It has been pointed out that cells synthesizing a detectable amount of gamma crystallins never synthesize DNA.

The data suggest that all the cells which form the new lens pass through a period of DNA synthesis, which starts approximately five days following lens removal. However, not all cells which are activated to DNA synthesis participate in lens formation. Thus, DNA synthesis is a necessary but not sufficient condition for transformation of iris cells into the lens cells.
Tissue transplantation immunity in the adult newt, Diemictylus viridescens. III. The effects of X‐irradiation and temperature on the allograft reaction
Authors: Cohen Nicholas
Published: June 2005

Graded dosages of x‐irradiation from 500r to 3000r inhibited destruction of Diemictylus viridescens allografts at 23 ± 0.5°C for at least as long as the survival time of the hosts (up to 35 days). Lymphocytes were observed in 20% of the grafts whose hosts received 500r and 1000r but they were present in far weaker concentrations than seen in any control grafts at all stages of rejection. No lymphocytes were evident in any grafts on hosts irradiated with 1500r, 2000r, and 3000r.

The effects of various temperatures on allograft rejection in the newt were also examined. There was no difference in the mean survival times of grafts maintained at 30°C and 23°C. At 20°C, however, hemostasis and hemorrhaging were significantly delayed by a factor of 1.6 and 1.7 times, respectively, when compared with the findings at 23°C. At 10–15°C, no hemostasis or hemorrhaging were displayed for 191 days after transplantation. Lymphocytes, however, were apparent in very low concentrations in the tissues of some of the grafts and localized destruction of a few melanophores were noted. Two grafts maintained at 10–15°C for 155 days and then transferred to 20°C were completely destroyed within 36 days. This destruction was more rapid than for grafts initially maintained at 20°C.
Osmotic hemolysis of the camel's erythrocytes. I. A microcinematographic study
Authors: Perk K.
Published: June 2005

Gradual osmotic hemolysis of camel erythrocytes was observed by means of phase contrast microscopy and recorded by microcinematographic methods. It was found that the normal ovoid erythrocytes become spherical when the solution surrounding the erythrocytes is diluted ionically, and they swell to 240% of the initial volume. After hemolysis the erythrocyte membranes (ghosts) revert to their original oval form.

Comparative studies of osmotic fragility tests on red blood cells of growing and adult camels showed the presence of two distinct cell populations in growing camels. One corresponds to the adult blood. The second cell type is more resistant to osmotic pressure and is found only in the young camel.
An investigation recording all salamanders which can and cannot regenerate a lens from the dorsal iris
Authors: Stone L. S.
Published: June 2005

A brief description of lens regeneration is given of all the 21 salamanders which can regenerate a lens from the dorsal iris after lentectomy. Illustrations of all but one are shown, 18 of which are from eyes of species which were lentectomized by the author. Eleven species of salamanders are American, eight are European and two are Japanese. Table 1 lists all of the 21 species of salamanders representing different genera which regenerate a lens and all of the eight species, also of different genera, which fail to regenerate a lens.

All members of the genus Triturus so far examined regenerate a lens and all of the Amblystomidae which have been tested do not. One species of the genus Eurycea regenerates a lens while another in the same genus does not. It is suggested that hybridization might be attempted between two similar closely related species for an examination of the ability of lens regeneration in the offspring.

Since there are more species of salamanders distributed over the American continent than in any other part of the world there is an unique opportunity to discover how widespread this phenomenon is for lens regeneration from the dorsal iris. Methods (table 1) and techniques are described for making serial sections of eyes.
Cell loss in the trochlear nucleus of the chick during normal development and after radical extirpation of the optic vesicle
Authors: Cowan W. M. , Wenger Eleanor
Published: June 2005

Counts have been made of the number of cells in the trochlear nucleus in a series of 22 normal chicks between the ninth day of incubation and the seventy‐fifth day after hatching, and in seven animals in which the optic vesicle and adjoining mesoderm were removed during the second day of incubation. Between the ninth and seventeenth days of incubation the number of cells in the normal trochlear nucleus declines from just under 1400 to a little under 700, indicating a cell loss of approximately 50% over this eight day interval. From the seventeenth day onwards there is a further slight fall to between 500 and 600 cells and this number is maintained into the third month after hatching. Following excision of the optic vesicle there is an earlier, and more severe, loss of neurons in the trochlear center, the number of cells being reduced to just under 1000 at the eleventh day of incubation and falling to just over 300 by the sixth day after hatching. Despite this marked cell loss, at no stage is there any gross evidence of neuronal disintegration or phagocytosis. The possible factors responsible for the normally occurring cell loss and for the hypoplasia in the trochlear nucleus after removal of the optic vesicle are discussed.
The eye and skeletal effects of two mutant alleles at the microphthalmia locus of Mus musculus
Authors: Packer Susan O.
Published: June 2005

The mi/mi mouse has a severe microphthalmia, its skeleton shows an almost complete absence of secondary bone resorption, and its eyes and hair have no pigment. The Miwh/Miwh mouse is white with a reduced eye size.

The mi/mi eye was first distinguished during the tenth day of embryonic development by an abnormally thick pigment layer and a weakly invaginated optic cup. These abnormalities persisted in the older embryos. Normal closure of the mutant choroid fissure was prevented by the inversion of the pigment layer in this region. An eversion of the nervous retina and derangement of the pigment layer were observed in the Miwh/Miwh eye during the eleventh day of development. These abnormalities led to the formation of a typical coloboma. Subsequent abnormalities of the mi/mi and Miwh/Miwh eyes were attributable to the colobomata and the consequent lack of intraocular pressure. Counts of mitoses in the pigment and nervous layers of the optic cups showed that there were increased numbers of mitoses in the pigment layers of both the mi/mi and Miwh/Miwh eyes.

The mi/mi osteoclasts were almost uniformly small and rounded and had significantly fewer nuclei than the large, irregular, multinucleated normal osteoclasts. Osteoclast counts indicated that the mutant parietal bone is not deficient in osteoclasts and may have higher than normal numbers. Mutant osteoclasts were not abnormal in the appearance of their nuclei, frequency of occurrence of cytoplasmic vacuoles, or amount of cytoplasmic basophilia, RNA, or foaminess. While normal osteoclasts contained essentially no glycogen, mi/mi osteoclasts contained, as a group, large amounts of glycogen.
Hypophysectomy and forelimb regeneration in Ambystoma opacum larvae
Authors: Liversage Richard A.
Published: June 2005

Larvae of Ambystoma opacum ranging in length from 25–56 mm were included in this work, which was designed to determine the effects of hypophysectomy upon the initiation and continuation of regenerative processes in forelimbs. Included in this work are 111 forelimbs from 92 larvae which comprise three experimental, one sham control and one normal control series.

Attention was drawn to a possible relationship between the hypophysis and forelimb regeneration and whether the presence of the pituitary is essential for limb regeneration in this larva. In this approach, hypophysectomy was followed by either immediate amputation or by a recuperation period (which varied in length depending upon the experimental procedure) before the forelimb was amputated. In the latter approach, a recovery period was considered necessary in order to eliminate the possibility of residual pituitary hormones (remaining in the animal for short periods following hypophysectomy) having an influence upon the various target endocrine organs and, ultimately, the regeneration of the forelimb.

The results from this investigation show that the presence of the pituitary is not prerequisite for larval forelimb regeneration nor for the survival of the animal. In addition, growth and development of the experimental larvae continued and appeared normal, compared to control animals, up to the beginning of metamorphosis. All hypophysectomized larvae died, however, as metamorphosis began indicating that various pituitary‐endocrine interrelationships are essential for metamorphosis.
In vitro differentiation of tooth rudiments of embryonic mice. I. Transfilter interaction of embryonic incisor tissues
Authors: Koch William E.
Published: June 2005

The mandibular incisor rudiment of the 16 day mouse embryo may be separated by enzymatic treatment into an epithelial covering and an inner mesenchymal papilla. Each separated tissue fails to differentiate when grown singly in vitro, but odontocytes, amelocytes, and their extracellular matrices are noted in cultures of recombined tissues. Separated tissues also fail to differentiate on collagen gels. Both the mesenchymal papilla and the internal dental epithelium differentiate when placed on opposite sides of a Millipore membrane. Cultures of 11 days growth show odontocytes with deposited alcian blue positive matrix; this matrix is found both within and on the surface of the membrane. Amelocytes deposit eosin‐positive extracellular matrix onto the filter surface. Calcification of odontocyte‐deposited matrix, similar to that of dentinal matrix of neonatal incisors, is shown by staining with von Kossa's stain. Transfilter interaction of these embryonic tissues leads, therefore, to their differentiation and deposition of characteristic extracellular matrices.
Sodium fluxes in fresh‐water turtles
Authors: Dunson William A.
Published: June 2005

Fresh‐water softshell turtles (Trionyx spinifer) showed net uptake of sodium from solutions as dilute as 5 m̈M. Chloride uptake could be accounted for by passive processes. There was no net uptake of potassium. Net sodium uptake was inhibited by low temperatures. Hibernation resulted in decreases in the sodium concentration and osmotic pressure of the plasma.

Influx and efflux of sodium in the fresh‐water turtle Pseudemys scripta varied from 0.04 to 10.1 m̈moles/(100 g hour). In hatchling turtles, the exchangeable sodium pool was 96% of the total sodium. The exchangeable pool was subdivided into at least two compartments, one rapidly and the other slowly exchanging. The latter compartment was 19 times larger than the former.

Pseudemys scripta, was found to have a system for active uptake of sodium. This involves the membranous lining of the pharynx, the cloacal bursae and the cloaca. Aside from the skin and the shell, these are the only tissues in contact with environmental water. The cloacal region accounted for 48 to 68% of the sodium influx rate.
The central nervous organization underlying control of antagonistic muscles in the crayfish. II. Coding of position by command fibers
Authors: Kennedy Donald , Evoy William H. , Dane Benjamin , Hanawalt Joanna T.
Published: June 2005

Single central interneurons that produce flexion or extension in the crayfish abdomen act in a coordinated fashion upon several ganglia. Each of several elements evoking a similar type of movement has a unique distribution of output to ganglionic centers: thus one of them may produce primarily rostral extension or flexion, another a primarily caudal movement, still another a more general one. Each motor command therefore appears to code for a specific abdominal geometry. Some units produce complex, cyclic motor outflow to postural muscles of the abdomen, or to the appendages.
Antagonism between prolactin and thyroid hormone in amphibian development
Authors: Etkin W. , Gona A. G.
Published: June 2005

Tadpoles were treated with intraperitoneal injections of mammalian prolactin and growth hormone (NIH). The growth rate of hypophysectomzied tadpoles (R. pipiens) was accelerated by both hormones, prolactin having the greater effect. Metamorphosis in the bullfrog (R. catesbeiana) was inhibited by prolactin but not by growth hormone. The results are interpreted to indicate a general antagonism between prolactin and thyroid hormone in amphibian development with respect to both growth rate and metamorphosis.
Tissue interactions in the development of ptilopody and brachydactyly in the chick embryo
Authors: Goetinck P. F.
Published: June 2005

One of the characteristics of the Brahma breed of chickens is that the scales along the fourth tarsometatarsus and digit IV are replaced by one or more rows of feathers. This triat known as ptilopody is associated with another trait, brachydactyly, a reduction in length of digit IV. The interactions between mesoderm and ectoderm in the development of the two traits were analyzed by recombining mesodermal and ectodermal components of 3‐day‐old Brahma and White Leghorn embryos. Based on the phenotypes of the composite limbs observed at a total age of 17 days, it is concluded that brachydactyly results from an effect of the Brahma genotype on the mesoderm only, while the ptilopody phenotype results from an action of this genotype on both the mesoderm and ectoderm of the limb. With respect to ptilopody, the results are interpreted to mean that the Brahma genotype acts by lowering in the ectoderm the threshold of response to mesodermal feather induction and also by reinforcing the feather inductive capacity of the mesoderm.
An autoradiographic study of the sites of protein synthesis in the epidermis of the Indigo snake (Drymarchon corais couperi)
Authors: Roth Sanford I. , Baden Howard P.
Published: June 2005

In order to delineate more clearly the sites of protein synthesis during the synchronous proliferation of reptilian epidermis, H3‐leucine was injected intradermally into the Indigo snake (Drymarchon corais couperi) at various times in the sloughing cycle. Autoradiograms were made of biopsies, taken during the early and late proliferative stages of the molting cycle. These confirmed morphologic observations (Roth and Jones, '66) that moderate numbers of spinous cells are added to the α‐layer during the resting phase. The number of cells added, and the amount of protein synthesized, reaches a maximum in the midresting phase and then decreases. No synthesis of upper α‐layer, μϵσºζ‐layer or β‐layer proteins occurs during the resting phase. Synthesis of the specialized proteins of the β‐layer, the μϵσºζ‐layer and the upper stratum of the α‐layer occurs during the proliferative phase, after the cells have left the basal layer, (while they represent inner epidermal generation), in contrast to mammalian epidermis in which the fibrous proteins are largely synthesized in the basal layer and the lower‐most spinous cells.