bluuebunny/crossref_metadata_2025_split huggingface dataset:
A premature acrosome reaction is programmed by mouse t haplotypes during sperm differentiation and could play a role in transmission ratio distortion
Authors: Brown Judith , Cebra-Thomas Judith A. , Bleil Jeffrey D. , Wassarman Paul M. , Silver Lee M. 
Published: April 2021

ABSTRACT
Mouse t haplotypes are variant forms of chromosome 17 that can be transmitted at non-Mendelian ratios by heterozygous +/t males. The accumulated genetic data indicate that ’ +-sperm’ and ‘t-sperm’ are produced in equal numbers but that most ‘+-sperm’ are rendered dysfunctional, so that ‘t-sperm’ have a relative advan-tage at fertilization. To date, the basis for this t-induced sperm dysfunction has remained unknown. Here we demonstrate that a high proportion of sperm obtained from certain strains of +/t mice undergo a premature acrosome reaction under in vitro capacitation conditions.
The simplest interpretation of these data, in conjunction with previous results, is that developing ‘+-spermatids’ are preprogrammed by ‘i-spermatids’ to undergo this premature reaction. Since acrosome-reacted sperm are unable to participate in the process of fertilization, this defect could account for the extreme distortion of transmission ratio observed from mice heterozygous for a class of complete t haplotypes.
Mitotic domains reveal early commitment of cells in Drosophila embryos
Authors: Foe Victoria E. 
Published: April 2021

ABSTRACT
In embryos of Drosophila melanogaster all the nuclei in the syncytial egg divide with global synchrony during the first 13 mitotic cycles. But with cellularization in the 14th cycle, global mitotic synchrony ceases. Starting about one hour into the 14th interphase, at least 25 ‘mitotic domains’, which are clusters of cells united by locally synchronous mitosis, partition the embryo blastoderm surface into a complex fine-scale pattern. These mitotic domains, which are constant from one embryo to the next, fire in the same temporal sequence in every embryo. Some domains consist of a single cell cluster straddling the ventral or dorsal midline. Most consist of two separate cell clusters that occupy mirror-image positions on the bilaterally symmetric embryo. Others comprise a series of members present not only as bilateral pairs but also as metameric repeats. Thus a domain can consist of either one, two, or many (if metamerically reiterated) clusters of contiguous cells. Within each cluster, mitosis starts in a single cell or in a small number of interior cells then spreads wave-like, in all directions, until it stops at the domain boundary. Each domain occupies a specific position along the anteroposterior axis - as determined by the expression pattern of the engrailed protein, and along the dorsoven-tral axis - as determined by cell count from the ventral midline.
The primordia of certain larval structures appear to consist solely of the cells of one specific mitotic domain. Moreover, cells in at least some mitotic domains share specific morphogenetic traits, distinct from those of cells in adjacent domains. These traits include cell shape, spindle orientation, and participation by all the cells of a domain in an invagination. The specialized behaviors of the various mitotic domains transform the monolayer cell sheet of the blastoderm into the multilayered gastrula. I conclude that the fine-scale partitioning of the newly cellularized embryo into mitotic domains is an early manifestation of the commitment of cells to specific developmental fates.
Control of peripheral glial cell proliferation: enteric neurons exert an inhibitory influence on Schwann cell and enteric glial cell DNA synthesis in culture
Authors: Eccleston P. A. , Bannerman P. G. C. , Pleasure D. E. , Winter J. , Mirsky R. , Jessen K. R. 
Published: April 2021

ABSTRACT
Neuronal membranes from rat dorsal root ganglia provide a mitogenic signal to cultured Schwann cells and it has been suggested this is an important factor in regulating Schwann cell numbers during development. In this study, the influence of enteric neurons on the DNA synthesis of both Schwann cells and enteric glia has been investigated as well as the effect of axonal membrane fractions (axolemma) on enteric glia.
The proliferation rate of rat Schwann cells and enteric glia was assessed in culture using [3H]thymidine uptake and autoradiography in combination with immunolabelling to identify cell types. When purified rat Schwann cells were co-cultured with guinea pig enteric neurons, their DNA synthesis rate was reduced compared with control cultures of pure Schwann cells or Schwann cells not close to neurites or neuronal cell bodies. Nevertheless, in accordance with previous findings that sensory neurons stimulate Schwann cell division, these Schwann cells increased their DNA synthesis rate when in contact with neurites from purified guinea pig or adult rat dorsal root ganglion neurons and on exposure to bovine axolemmal fractions. The enteric neurons also suppressed the DNA synthesis of enteric glia in co-cultures of purified enteric neurons and enteric glia, while bovine axolemma stimulated their DNA synthesis.
These results indicate that a mitotic inhibitory signal is associated with enteric neurons and can exert its effect on both Schwann cells and enteric glia, and that enteric glia, like Schwann cells, are stimulated to divide by axolemmal fractions. It thus seems possible that during development glial cell numbers in the peripheral nervous system may be controlled by both positive and negative regulators of cell growth.
Epigenetic and genetic factors affect transgene methylation imprinting
Authors: Sapienza Carmen , Paquette Jean , Tran Thu Hang , Peterson Alan 
Published: April 2021

ABSTRACT
In some lines of transgenic mice, the methylation of Mspl sites within or adjacent to the transgene locus is affected by the sex of the parent from which the transgene is inherited. These differences are consistent with a role for DNA methylation in genome imprinting. In a previous report, we noted that in one such line, all offspring of females exhibited hypermethylation of the transgene while only some offspring of males carried a hypometh-ylated transgene. In this report, we provide evidence that this phenomenon is controlled by at least two factors, one of which acts in cis and is dependent on the transgene locus, and one of which acts in trans and is supplied by the maternal genome. We also provide evidence that there are genetic differences between inbred mouse strains in the trans-acting factor.
Development and fertility of ovaries in the B6.YDOM sex-reversed female mouse
Authors: Taketo-Hosotani Teruko , Nishioka Yutaka , Nagamine Claude M. , Villalpando Irma , Merchant-Larios Horacio 
Published: April 2021

ABSTRACT
When the Y chromosome of Mus musculus domesticas (YDOM) was introduced onto the C57BL/6 (B6) mouse background, half of the XY progeny (B6.YDOM) developed bilateral ovaries and female internal and external genitalia. We examined the fertility of the B6.YDOM sex-reversed female mouse. The chromosomal sex of the individual mouse was identified by dot hybridization with mouse Y chromosome-specific DNA probes. The results indicated that all XY females lacked regular estrous cyclicity although most were able to mate and ovulate after treatment with gonadotropins. When they had been ovariectomized and grafted with ovaries from the XX female litter mate, they initiated estrous cycli-city. Reciprocally, the XX female that had received XY ovarian grafts did not resume estrous cyclicity.
Development of the XY ovary was morphologically comparable to the XX ovary until 16 day of gestation (d.g.), when most germ cells had reached the zygotene or pachytene stage of meiotic prophase. However, by the day of delivery (19 or 20 d.g.), no oocyte remained in the medullary cords of the XY ovary. In the control XX ovary, the first generation of follicles developed in the medullary region, and 5Δ-3β-hydroxysteroid dehydrogenase (3β-HSDH) activity appeared first in the stromal cells around growing follicles by 10 days after birth. In contrast, in the XY ovary, follicles were not formed in the medullary region, and 3β-HSDH activity appeared in epithelial cells of the oocyte-free medullary cords. Primordial follicles in the cortex region continued development in both the XX and XY ovaries.
These results suggest that the XY female is infertile due to a defect inside the XY ovary. The prenatal loss of oocytes in the medullary cords may be a key event leading to abnormal endocrine function, and thereby, the absence of estrous cyclicity.
Autonomous expression of tissue-specific genes in dissociated sea urchin embryos
Authors: Stephens Laurie , Kitajima Takashi , Wilt Fred 
Published: April 2021

ABSTRACT
The effects of disrupting cell interactions in early development were investigated by examining the accumulation of a primary mesenchyme specific transcript (SM50) and an aboral ectoderm-specific transcript (Spec 1) in cultures of sea urchin embryos that were dissociated at early stages and then cultured in CFSW. The expression of both SM50 and Spec 1 is temporally correct and remains restricted to the appropriate cell types, even if the embryo is dissociated as early as the 2-cell stage and maintained as a suspension of single cells. This result is consistent with the idea that the specificity of expression of these two genes, each characteristic of different lineages, is strongly regulated by information in the egg. Average SM50 expression is half that of intact embryos, but Spec 1 expression is very low, only 10–20 % of intact controls, suggesting some differences in the response of the two genes to lack of close cell interactions.
Retarded gastrulation and altered subsequent development of neural tissues in heparin-injected Xenopus embryos
Authors: Mitani Shohei 
Published: April 2021

ABSTRACT
Gastrulation was examined in Xenopus embryos injected with various polysaccharides into the blastocoel cavity. The progression of gastrulation was assessed by observing pigmentation and yolk plug size in vegetative view embryos. In heparin-or dextran-sulphate-injected embryos, gastrulation was significantly retarded. This was further confirmed in tissue sections of embryos. In contrast, no such retardation was found in embryos injected with hyaluronic acid or chondroitin sulphate. A quantitative analysis showed that the extent of retardation in heparin-or dextran-sulphate-injected embryos was dose-dependent and that, after the initial retardation of up to 2–3 h, gastrulation progressed at a similar rate to controls.
At the time when untreated sibling embryos hatched, embryos injected with heparin or dextran sulphate showed abnormalities in their external appearance and swimming behavior in a dose-dependent manner. When these embryos were examined histologically or immuno-histochemically using tissue-specific monoclonal antibodies, it was found that central nervous system (CNS), especially the brain and eye structures, were most severely damaged. The extent of damage was again dosedependent. In contrast, neural-crest-derived melano-phores were abundant even in aneural larvae. No such change was found in embryos injected with hyaluronic acid or chondroitin sulphate.
Nucleotide sequence, chromosomal localization and developmental expression of the mouseint-1-related gene
Authors: McMahon Jill A. , McMahon Andrew P. 
Published: April 2021

ABSTRACTcDNA clones encoding the murine int-1 -related protein (m-irp) were isolated from an 8.5-day mouse embryo library, m-irp and its human counterpart, h-irp, share extensive nucleotide homology in coding (92 %) and 3’ untranslated (69 %) regions. At the amino acid level, m-irp and h-irp share 97 % of amino acids including all 24 cysteine residues, which are highly conserved among members of the int-1 family. However, in contrast to h-irp and int-1, the predicted m-irp protein sequence did not contain a signal peptide sequence. Analysis of polymerase chain reaction, amplified cDNA, and genomic sequences strongly suggests that a single-base substitution has created a new S’ splice site 17 bp 5’ of a highly conserved splice site. Splicing at this new site generates a mRNA-encoding an amino-terminal truncated protein. Splicing at the conserved splice site generates a mRNA species encoding a protein with a signal peptide sequence similar to h-irp. Close linkage between m-irp and the met oncogene maps m-irp sequences to proximal mouse chromosome 6. Adult and fetal expression of m-irp was examined by RNA blot analysis. Adult expression of m-irp is restricted to lungs and heart, and fetal expression, to placental tissue and to all stages of fetal development examined. In situ hybridization localized early fetal m-irp expression to the pericardium of the heart, to the umbilicus and associated allantoic mesoderm, and to the ventral lateral mesenchyme tissue surrounding the umbilical vein in the fetus. These results suggest a role for m-irp in the development of fetal allantoic communication.
Analysis of maternal effect mutant combinations elucidates regulation and function of the overlap of hunchback and Krüppel gene expression in the Drosophila blastoderm embryo
Authors: Gaul Ulrike , Jäckle Herbert 
Published: April 2021

ABSTRACT
The metameric organisation of the Drosophila embryo is generated early during development, due to the action of maternal effect and zygotic segmentation and homeotic genes. The gap genes participate in the complex process of pattern formation by providing a link between the maternal and the zygotic gene activities. Under the, influence of maternal gene products they become expressed in distinct domains along the anteroposterior axis of the embryo; negative interactions between neighboring gap genes are thought to be involved in establishing the expression domains. The gap gene activities in turn are required for the correct patterning of the pairrule genes; little is known, however, about the underlying mechanisms.
We have monitored the distribution of gap and pairrule genes in wild-type embryos and in embryos in which the anteroposterior body pattern is greatly simplified due to combinations of maternal effect mutations (staufen exuperantia, rusa exuperantia, bicoid oskar, bicoid oskar torsolike, vasa torso exuperantia). We show that the domains of protein distribution of the gap genes hunchback and Krüppel overlap in wild-type embryos. Based on the analysis of the maternal mutant combinations, we suggest an explanation of how this overlap is generated. Furthermore, our data show that different constellations of gap gene activities provide different input for the pair-rule genes, and thus strongly suggest that the overlap of hunchback and Krüppel in wild-type is functional in the formation of the patterns of pair-rule genes.
Imaginal discs can be recovered from cultured embryos mutant for the segment-polarity genes engrailed, naked and patched but not from wingless
Authors: Simcox Amanda A. , Roberts Ian J. H. , Hersperger Evelyn , Gribbin M. Clare , Shearn Allen , Whittle J. Robert S. 
Published: April 2021

ABSTRACT
Drosophila embryos homozygous for strong mutations in each of the segment-polarity genes wingless (wg), engrailed (en), naked (nkd) and patched (ptc) form a larval cuticle in which there is a deletion in every segment. The mutant embryos normally fail to hatch but by in vivo culture we were able to show which could produce adult structures. Cultured wg− embryos did not produce any adult structures. Cultured en− embryos produced eye-antennal derivatives and rarely produced partial thoracic structures. nkd− and ptc− embryos produced eye-antennal and thoracic derivatives. The nkd− and ptc− thoracic imaginal discs developed with an abnormal morphology and abnormal pattern of en-expression. Our findings are consistent with the idea that the thoracic imaginal discs derive from two adjacent groups of cells that express wg and en respectively in the embryo.
Retinoic acid induces a pattern of digits in anterior half wing buds that lack the zone of polarizing activity
Authors: Eichele Gregor 
Published: April 2021

ABSTRACT
Wing buds whose posterior half is excised, develop into wings lacking distal structures. However, such experimentally generated preaxial half wing buds can be rescued by implanting a retinoic-acid-releasing bead at their anterior margin. The polarity of the pattern that originates from preaxial half wing buds is reversed. For example, instead of a 234 digit pattern typical for normal wings, the order of digits is 432. This result implies that retinoic acid has the capacity to reprogram anterior limb bud tissue, and that the resulting change in cell fate does not depend on the presence of posterior tissue regions such as the zone of polarizing activity (ZPA).
Expression of a Drosophila mRNA is under circadian clock control during pupation
Authors: Lorenz Lori J. , Hall Jeffrey C. , Rosbash Michael 
Published: April 2021

Abstract
Rhythmic eclosion of Drosophila adults requires per gene function. We have found that a previously identified 0.9 kb RNA transcribed from DNA adjacent to per becomes abundantly expressed during pupation, just prior to eclosion. The daily synchronized emergence of young adults, coupled with a subsequent rapid decay of the transcript, is responsible for what previously appeared to be cycling of the 0.9 kb RNA in adults. In situ hybridization analyses localize the 0.9 kb transcript to the epidermis of newly eclosed adults. Conceptual translation of genomic DNA and cDNA sequences predicts that the 0.9 kb transcript produces a 261 amino acid protein containing a putative signal sequence for membrane transport at its amino terminus. Pupae that reach the same stage of development at slightly different times of day show a subsequent synchronized rise in 0.9 kb RNA levels, indicating that the expression of this transcript is under circadian clock control.
Patterns of expression of a 15K β-D-galactoside-specific lectin during early development of the avian embryo
Authors: Levi Giovanni , Teichberg Vivian I. 
Published: April 2021

ABSTRACT
We have determined, by immunohistochemical and biochemical techniques, the distribution of an endogenous β-D-galactoside-blnding lectin between the early primitive streak stage and the 5th day of embryonic development of the chick. The lectin, which was purified from the pectoral muscle of 16-day-old chick embryos, migrates on SDS–PAGE as a single polypeptide of relative molecular mass 15 × 103. Antibodies to this pure lectin interact with the 15K (K=103Mr) polypeptide as well as with a 6.5K polypeptide; this second component appears to be antigenically related to the 15K lectin, as antibodies affinity purified on the 15K band recognize both polypeptides.
In early stages of development, lectin immunoreactivity was present in most cells of the epiblast and hypoblast in the region of the primitive streak, while towards the edge of the area pellucida the epiblast was stained less intensely. During gastrulation, strong immunoreactivity was present also in migrating cells and in the mesoblast, while at the margin of the area pellucida the epiblast was negative.
Up to the 10-somite stage, lectin immunoreactivity was present in the somites, neural tube and presumptive cardiac region; the non-neural ectoderm and the extra-cellular matrix were not labeled; the predominant immunoreactive component at this stage of development was the 6.5K polypeptide. Later in development, the lectin immunoreactivity gradually disappeared from the dermamyotome and nervous system to reappear conspicuously as soon as a differentiated myotome could be detected. Immunoreactivity was very high in the myotome, skeletal and cardiac muscles and transient in smooth muscles. The only region of the nervous system that continued to express the lectin throughout development was the trigeminal (semilunar) ganglion; in all other regions of the nervous system, the lectin immuno-reactivity disappeared early in development to be re-expressed only much later. The lining epithelium of the digestive tract and other endodermal derivatives expressed the lectin transiently. In the extraembryonic membranes, immunoreactivity to the lectin was observed in the yolk sac and in both layers of the amnion.
The striking regulation of the expression of this endogenous lectin suggests that its functions are linked to cell proliferation and/or to the selective expression of a developmentally-timed cell phenotype.
Multiple steps in the localization of bicoid RNA to the anterior pole of the Drosophila oocyte
Authors: Johnston Daniel St. , Driever Wolfgang , Berleth Thomas , Richstein Sibyll , Nüsslein-Volhard Christiane 
Published: April 2021

ABSTRACT
The anterior region of the Drosophila embryonic pattern is determined by a gradient of the bicoid (bed) protein. The correct formation of this gradient requires the localization of bed RNA to the anterior pole of the egg. Here we use a wholemount in situ technique to examine the process of bed RNA localization during oogenesis and embryogenesis. While bed protein becomes distributed in a gradient that extends throughout the anterior two thirds of the early embryo, bed RNA remains restricted to a much smaller region at the anterior pole. The difference between these distributions indicates that the shape of the protein gradient must depend to some extent on the posterior movement of the protein after it has been synthesized.
Four distinct phases of bed RNA localization can be distinguished during oogenesis. Between stages 6 and 9 of oogenesis, the RNA accumulates in a ring at the anterior end of the oocyte. During the second phase, in stage 9-10a follicles, the RNA also localizes to the apical regions of the nurse cells, demonstrating that the nurse cells possess an intrinsic polarity. As the nurse cells contract during stages 10b–ll, all of the bed RNA becomes localized to the cortex at the anterior end of the oocyte. During a final phase that must occur between stage 12 of oogenesis and egg deposition, the RNA becomes localized to a spherical region that occupies a slightly dorsal position at the anterior pole.
Mutations in the maternal-effect genes, exuperantia (exu) and swallow (sw), lead to an almost uniform distribution of bed RNA in the early embryo, while staufen (stau) mutations produce a gradient of RNA at the anterior pole, exu mutations disrupt the second stage of bcd RNA localization during oogenesis, su’w mutations disrupt the third, and stau mutations affect the fourth phase.
int-1 - a proto-oncogene involved in cell signalling
Authors: Mcmahon Andrew P. , Moon Randall T. 
Published: April 2021

ABSTRACT
The int-1 gene was originally identified as a locus activated by mouse mammary tumor virus insertion. Cloning and sequencing of the mouse gene indicates that int-1 encodes a 41K, 370 amino acid, cysteine-rich protein with a potential hydrophobic signal peptide sequence. Expression studies clearly indicate that int-1 enters the secretory pathway and is probably secreted, although definitive evidence is lacking.
Drosophila int-1 encodes the wingless gene, wingless, a segment-polarity gene, is required for the establishment of normal pattern in each segment. Genetic studies indicate that the wingless protein is probably secreted since it is required for the maintenance of stable gene expression in neighboring cells.
int-1 is also expressed during early neural stages of frog and mouse development. In the mouse, where expression is well characterized, int-1 RNA is restricted to the dorsal midline of the neural tube. By analogy with Drosophila, int-1 may operate to specify position within this structure. To test this idea, we have interfered with normal int-1 expression by injection of int-1 RNA into frog embryos. This results in a striking and specific aberration, bifurcation of the anterior neural tube. Thus, it seems possible that in vertebrates int-1 is able to influence patterning events.