bluuebunny/crossref_metadata_2025 huggingface dataset:
hsp23 and hsp26 exhibit distinct spatial and temporal patterns of constitutive expression in Drosophila adults
Authors: Marin Raquel , Valet Jean Paul , Tanguay Robert M.
Published: May 2005

To determine differences in the patterns of expression of Drosophila small heat shock proteins (shsp) during normal development in the absence of stress, proteins obtained from head, thorax and gonads of young (0–12 h, 3 days), middle‐aged (3–6 days) and 15‐ to 20‐day‐old adult flies were separated on SDS‐PAGE gels and blotted with monoclonal antibodies against hsp23 and hsp26. hsp23 was found in the heads and gonads of young males and females. In contrast, the maximum expression of hsp26 was seen in gonads of young flies, and it was only lightly detected in the brain. The expression of both proteins decreased as flies aged. This age‐related decrease was particularly striking for hsp23 in females. The immunoblot results obtained were complemented by immunostaining of thin parasagittal sections of whole fly bodies Hsp23 was found to be expressed in the brain, thoracic ganglion, fat body and gonads of young (0‐12 h) males and females. On the other hand, hsp26 was essentially detected in ovaries and testes of these young flies. The analysis of the tissue expression of both proteins demonstrate that each shsp has a distinct cellular localization. In the central nervous system, hsp23 and hsp26 were present in the neurocytes of the brain and the thoracic ganglion. In addition, hsp23 (but not hsp26) was also detected in the central neuropile of these two organs. In testis, hsp26 was localized in the cytoplasm of spermatocytes and, probably, in the spermatid bundles. In contrast, hsp23 was detected at the periphery of cells (membranes). In ovorioles of newborn females the expression of hsp26 was stronger, and the maximum expression of hsp23 was only reached in older (2 days and more) flies. These results demonstrate that each shsp possesses a specific spatial and temporal pattern of expression in adults of Drosophila. The distinct tissue‐specific and age‐dependent expression of hsp23 and hsp26 suggests that these two proteins may have different functions in crucial organs of Drosophila. © 1993Wiley‐Liss, Inc.
Tissue‐specific expression of heat shock proteins of the mouse in the absence of stress
Authors: Tanguay Robert M. , Wu Y. , Khandjian E. W.
Published: May 2005

The steady‐state levels of four members of the heat shock proteins families (HSP84, HSC73, HSP71, and HSP25) were examined by immunoblot analysis of several different tissues of young and adult mice in the absence of stress. These hsps were detected in all tissues but their level was variable. The levels of HSC73 and HSP84 varied only slightly between different tissues in either young or adult mice, with the exception of skin where these hsps were found in reduced amounts. In contrast, the stress‐inducible member of the HSP70 family, HSP71, was found to be expressed in all tissues but in amounts which differed by as much as two orders of magnitude between tissues. In general, the levels of both HSP71 and HSP25 were found to be tissue dependent, with higher levels found in tissues such as stomach, intestine, colon and bladder, tissues which are exposed to toxic environmental or metabolic products, and which may concentrate these substances by water resorption and/or be exposed to them for longer periods. The levels of HSP71 and HSP25 were generally positively correlated both in young and adult mice although this correlation was not found in certain tissues such as kidney, testes, and bone. Tissues of young mice contained lower amounts of HSP25 and HSP71 than were found in the same tissues from adults. We conclude that hsps are expressed in all tissues of the mouse in the absence of stress and that some organs, particularly those exposed to potentially toxic metabolites, show a higher level of expression of HSP71 and HSP25. © 1993Wiley‐Liss, Inc.
HSP86 and HSP84 exhibit cellular specificity of expression and co‐precipitate with an HSP70 family member in the murine testis
Authors: Gruppi Carol M. , Wolgemuth Debra J.
Published: May 2005

This study extends to the protein level our previous observations, which had established the stage and cellular specificity of expression of hsp86 and hsp84 in the murine testis in the absence of exogenous stress. Immunoblot analysis was used to demonstrate that HSP86 protein was present throughout testicular development and that its levels increased with the appearance of differentiating germ cells. HSP86 was most abundant in the germ cell population and was present at significantly lower levels in the somatic cells. By contrast, the HSP84 protein was detected in the somatic cells of the testis rather than in germ cells. The steady‐state levels of HSP86 and HSP84 paralleled the pattern of the expression of their respective mRNAs, suggesting that regulation at the level of translation was not a major mechanism controlling hsp90 gene expression in testicular cells. Immunoprecipitation analysis revealed that a 70‐kDa protein coprecipitated with the HSP86/HSP84 proteins in testicular homogenates. This protein was identified as an HSP70 family member by immunoblot analysis, suggesting that HSP70 and HSP90 family members interact in testicular cells. © 1993Wiley‐Liss, Inc.
Heat‐shock gene expression and cell cycle changes during mammalian embryonic development
Authors: Walsh David , Li Karen , Wass Jane , Dolnikov Alla , Zeng Frank , Zhe Li , Edwards Marshall
Published: May 2005

Synchronized regulation of cell division during gastrulation is essential for the regional proliferation of cells and pattern formation of the early CNS. The neural plate and neuroectoderm cells are a rapidly dividing and differentiating population of cells with a unique and rapid heat‐shock response. Heat shock and the heat‐shock genes were studied during neural plate development in a whole rat embryo culture system at 9.5‐11.5 days. A lethal heat shock can cause cell death and severe developmental defects to the forebrain and eye during organogenesis. Heat shock can also result in acquired thermotolerance whereby cell progression is delayed at the G1/S and S/G2 boundaries of the cell cycle. This delay in cell cycle progression caused an overall lengthening of the cell cycle time of at least 2 hr. The heat shock genes may therefore function as cell cycle regulators in neuroectoderm induction and differentiation. The kinetics and expression of the hsp genes were examined in neuroectodermal cells by flow cytometry and Northern analysis. The levels of hsp mRNA 27, 71, 73, and 88 were identified following exposure at 42°C (nonlethal), 43deg;C (lethal) and 42deg;/43deg;C (thermotolerant) heat shock. Examination of hsp gene expression in the neural plate showed tight regulation in the cell cycle phases. Hsp 88 expression was enhanced at Go and hsp71 induction at G2 + M of the cell cycle. Cells exposed to a thermotolerant heat shock of 42deg;C induced hsp71 mRNA expression in all phases of the cell cycle with the mRNA levels of hsp27, 73, and 88 increased but relatively constant. Following a lethal heat shock, dramatic changes in hsp expression were seen especially enhanced hsp71 induction in late S phase. The regulated expression of hsps during the cell cycle at various phases could play a unique and important role in the fate and recovery of neuroectoderm cells during early mammalian embryo development. © 1993Wiley‐Liss, Inc.
The Xenopus platelet‐derived growth factor α receptor: cDNA Cloning and demonstration that mesoderm induction establishes the lineage‐specific pattern of ligand and receptor gene expression
Authors: Jones Susan Dana , Ho Lap , Smith James C. , Yordan Cristina , Stiles Charles D. , Mercola Mark
Published: May 2005

We have cloned the Xenopus PDGF α receptor cDNA and have used this clone, along with cDNA encoding PDGF A, to examine their expression pattern in Xenopus embryos and to determine the factors responsible for lineage specificity. Recombinant Xenopus α receptor expressed in COS cells exhibits PDGF‐A‐dependent tyrosine kinase activity. We find that receptor mRNA is present in cultured marginal zone tissue explants and in animal cap tissue induced to form mesoderm either by grafting to vegetal tissue or by treatment with recombinant activin A. In contrast, PDGF A mRNA is expressed in cultured, untreated animal cap tissue and is suppressed by mesoderm induction. These results suggest that ectodermally produced PDGF A may act on the mesoderm during gastrulation and that mesoderm induction establishes the tissue pattern of ligand and receptor expression. © 1993Wiley‐Liss, Inc.
Site of action of imprinted genes revealed by phenotypic analysis of parthenogenetic embryos
Authors: Varmuza Susannah , Mann Mellissa , Rogers Ian
Published: May 2005

The phenotypes of early postimplantation parthenogenetic embryos were examined. The spectrum of phenotypes suggested that three stages are adversely affected by imprinting—implantation, pregastrulation, and postgastrulation. Survival of parthenogenetic embryos past these developmental blocks can be improved but not completely overcome by experimental asynchrony. These results suggest that imprinting may be “leaky” at early stages. © 1993Wiley‐Liss, Inc.
Giα2 mediates the inhibitory regulation of adenylylcyclase in vivo: Analysis in transgenic mice with Giα2 suppressed by inducible antisense RNA
Authors: Moxham Christopher M. , Hod Yaacov , Malbon Craig C.
Published: May 2005

The role of the GTP‐binding regulatory protein (G‐protein) Giα2 in vivo was explored using transgenic mice in which the α‐subunit of Giα2 was suppressed by antisense RNA. Rat hepatoma FTO‐2B cells provide an ideal test system for constructs employing the expression vector pPCK‐AS, designed to express antisense RNA at birth under the control of the phosphoenolpyruvate carboxykinase (PEPCK) promoter. Cells transfected with the expression vector containing a sequence antisense to Giα2 (pPCK‐ASGiα2) displayed expression of RNA antisense to Giα2 that, like transcription of the PEPCK gene, was inducible by cyclic AMP. Expression of RNA antisense to Giα2 and suppression of the expression of Giα2, but not Gsa and Giα3, was observed in the transfected FTO‐2B cells. BDF1 mice carrying the transgene displayed suppression of Giα2 in liver and fat, two targets for tissue‐specific expression of the PEPCK gene. The loss of Giα2 in white adipocytes of transgenic mice resulted in 3.1‐fold elevation of basal cyclic AMP accumulation. Cyclic AMP accumulation in response to stimulation by epinephrine (10μM) was normal in adipocytes of transgenic mice, demonstrating no alteration in the stimulatory adenylylcyclase capacity in the Giα2‐deficient cells. The inhibitory adenylylcyclase pathway, in sharp contrast, was severely blunted in response to challenge by the inhibitory A1‐purinergic agonist, (−)R‐N6‐phenylisopropyladenosine. These studies illuminate a critical role of Giα2 in the inhibitory adenylylcyclase signaling pathway in vivo. © 1993Wiley‐Liss, Inc.
Creating a conditional mutation of Wnt‐1 by antisense transgenesis provides evidence that Wnt‐1 is not essential for spermatogenesis
Authors: Erickson Robert P. , Lai Li‐Wen , Grimes Judy
Published: May 2005

We have used mice transgenic for an antisense construct for Wnt‐1 to study the role of this gene in post‐meiotic sperm development. The human PGK‐2 promoter provided levels of Wnt‐1 antisense mRNA in testes in 5 transgenic lines greatly in excess of Wnt‐1 mRNA concentrations, and Wnt‐1 mRNA levels were greatly decreased in the lines, by 98% in three of them. There was a general correlation between copy number of the insert, levels of antisense RNA, and decreases in mRNA. There was little effect of the antisense transgene on fertility or testicular histology suggesting that normal levels of Wnt‐ 1 transcript are not essential for spermatogenesis. © 1993Wiley‐Liss, Inc.
Embryonic and fetal rat myoblasts express different phenotypes following differentiation in vitro
Authors: Pin Christopher L. , Merrifield Peter A.
Published: May 2005

Myosin heavy chain (MHC) is encoded by a multigene family containing members which are expressed in developmental and fiber type‐specific patterns. In developing rats, primary (1°) and secondary (2°) myotjbes can be disfinguished by differences in MHC expression: 1° myotubes coexpress embryonic and slow MHC, while 2° myotubes initially express only embryonic MHC. We have used monoclonal antibodies which recognize the embryonic, slow, neonatal, and adult fast IIB/IIX MHCs to examine MHC accumulation in myoblasts obtained from hindlimbs of embryonic day (ED) 14 and ED 20 Sprague‐Dawley rats during differentiation in vitro. Embryonic myoblasts (ED 14), which develop into 1° myotubes in vivo, differentiate as myocytes or small myotubes (i.e., 1–4 nuclei) which express both embryonic and slow MHC. They do not accumulate detectable levels of neonatal or adult fast IIB/IIX MHC. Fetal myoblasts, which develop into secondary myotubes in vivo, fuse to form large myotubes (i.e., 10–50 nuclei) and express predominantly embryonic MHC at 3 days in culture. These myotubes accumulate neonatal and adult fast IIB/IIX isoforms of MHC and eventually contract spontaneously. In contrast to embryonic myotubes, they do not accumulate slow MHC. Our results demonstrate that embryonic and fetal rat myoblasts express different phenotypes in vitro and suggest that they represent distinct myoblast lineages similar to those previously described in chickens and mice. These two lineages may be responsible for the generation of distinct populations of 1° and 2° myotubes in vivo. © 1993Wiley‐Liss, Inc.
Pleiotropic effects of the Cardiac‐lethal gene in the axolotl (Ambystoma mexicanum)
Authors: Smith Steven C. , Armstrong John B.
Published: May 2005

Embryos of the axolotl affected with the cardiac‐lethal mutation form hearts that never begin to beat. A number of other traits characteristic of the mutant phenotype, including edema, underdeveloped gills, shorter stature, and aphagia (the inability to feed), were believed to be secondary effects of the absence of circulation. We have recently demonstrated that the pre‐cardiac mesoderm is directly affected by the c gene, making it unresponsive to normal inductive signals. In this study, we replaced part or all of the mutant pre‐cardiac mesoderm with wild‐type tissue, to produce embryos with normally beating hearts and circulation. As expected, most of the other mutant characteristics were also corrected. However, otherwise normal individuals remained aphagic. All embryos with beating hearts containing mutant tissue also suffered from an unexpected circulatory arrest some time after the onset of circulation. This apparently indicates that there are at least two tissues other than the myocardium which appear to be directly affected by the c gene. These previously unsuspected pleiotropic effects of the mutation may involve poorly‐characterized mesodermal‐neural crest inductive interactions and may also lead to a greater understanding of the link between congenital heart defects and feeding difficulties in humans. © 1993Wiley‐Liss, Inc.
Mechanism of action of developmentally regulated sea urchin inhibitor of eIF‐4
Authors: Jagus Rosemary , Huang Wun‐Ing , Hiremath Leena S. , Stern Brian D. , Rhoads Robert E.
Published: May 2005

The developmentally regulated inhibitor of eIF‐4 function found in unfertilized sea urchin eggs has been partially purified and its mechanism of action studied in vitro using purified recombinant eIF‐4α and cell‐free translation systems. The results demonstrate that although the phosphorylation of eIF‐4α is necessary to promote protein synthesis, it is not sufficient to maintain all aspects of eIF‐4 function. The egg inhibitor does not change eIF‐4α phosphorylation state. During the blockage of initiation caused by the egg inhibitor, eIF‐4α remains phosphorylated but accumulates in a 48S initiation intermediate. This suggests that the egg inhibitor functions by preventing the release of eIF‐4α from the small ribosomal subunit. The characteristics of the inhibitor in a reticulocyte translation system demonstrate that eIF‐4 activity is inhibited within 3–6 min. However, the inhibitor's characteristics in a mRNA‐dependent translation system contrast with this. Preincubation with the inhibitor for 5–25 min prior to the addition of mRNA does not prevent endogenous eIF‐4 from participating in translation but diminishes its ability to be reutilized, consistent with the accumulation of eIF‐4α on the small ribosomal subunit. The ribosomal localization of the inhibitor suggests that it could prevent eIF‐4α release by direct binding. The gradual inactivation of the inhibitor following fertilization indicates that it represents a component of a novel regulatory cascade that modulates eIF‐4 activity. © 1993 Wiley‐Liss, Inc.
Maturation hormone induced an increase in the translational activity of starfish oocytes coincident with the phosphorylation of the mRNA cap binding protein, eIF‐4E, and the activation of several kinases
Authors: Xu Zhe , Dholakia Jaydev N. , Hille Merrill B.
Published: May 2005

The stimulation of translation in starfish oocytes by the maturation hormone, 1‐methyladenine (1‐MA), requires the activation or mobilization of both initiation factors and mRNAs [Xu and Hille, Cell Regul. 1:1057, 1990]. We identify here the translational initiation complex, eIF‐4F, and the guanine nucleotide exchange factor for eIF‐2, eIF‐2B, as the rate controlling components of protein synthesis in immature oocytes of the starfish, Pisaster orchraceus. Increased phosphorylation of eIF‐4E, the cap binding subunit of the eIF‐4F complex, is coincident with the initial increase in translational activity during maturation of these oocytes. Significantly, protein kinase C activity increased during oocyte maturation in parallel with the increase in eIF‐4E phosphorylation and protein synthesis. An increase in the activities of cdc2 kinase and mitogen‐activated myelin basic protein kinase (MBP kinase) similarly coincide with the increase in eIF‐4E phosphorylation. However, neither cdc2 kinase nor MBP kinase phosphorylates eIF‐4E in vitro. Casein kinase II activity does not change during oocyte maturation, and therefore, cannot be responsible for the activation of translation. Treatment of oocytes with phorbol 12‐myristate 13‐acetate, an activator of protein kinase C, for 30 min prior to the addition of 1‐MA resulted in the inhibition of 1‐MA‐induced phosphorylation of eIF‐4E, translational activation, and germinal vesicle breakdown. Therefore, protein kinase C may phosphorylate eIF‐4E, after very early events of maturation. Another possibility is that eIF‐4E is phosphorylated by an unknown kinase that is activated by the cascade of reactions stimulated by 1‐MA. In conclusion, our results suggest a role for the phosphorylation of eIF‐4E in the activation of translation during maturation, similar to translational regulation during the stimulation of growth in mammalian cells. © 1993 Wiley‐Liss, Inc.
Expression of elongation factor 1α (EF‐1α) and 1βγ (EF‐1βγ) are uncoupled in early Xenopus embryos
Authors: Morales Julia , Bassez Thérèse , Cormier Patrick , Mulner‐Lorillon Odile , Bellé Robert , Osborne H. Beverley
Published: May 2005

In the amphibian Xenopus laevis, the elongation factor 1α proteins (EF‐1α) synthesised in oocytes and somatic cells correspond to distinct gene products. Furthermore, the somatic EF‐1α gene (EF‐1αS) produces one of the most highly expressed early zygotic transcripts in the embryo. The functional recycling of EF‐1α (conversion of EF‐1α‐GDP to EF‐1α‐GTP) is assured by the EF‐1βγ complex. We show here that in Xenopus laevis embryos, contrary to the situation for EF‐1α, EF‐1β, and EF‐1γ mRNAs are transcribed from the same genes in oocytes and somatic cells. In addition, the onset of transcription of the EF‐1β and EF‐1γ genes from the zygotic gencme occurs several hours after that of the somatic EF‐1αS gene. Therefore, during early Xenopus development the expression of these three elongation factors is not co‐ordinated at the transcriptional level. The consequences of this uncoupling on the efficiency of translational elongation in the early Xenopus embryo are discussed. © 1993 Wiley‐Liss, Inc.
Tubulin mRNA instability and stabilization by protein synthesis inhibitors are reproducible in nontranslating extracts from Chlamydomonas
Authors: Baker Ellen J.
Published: May 2005

In Chlamydomonas rein‐hardtii, flagellar amputation stimulates an induction in the synthesis of flagellar proteins which allows the cells to rapidly regenerate their flagella. The induction involves the coordinate accumulation and rapid degradation of a large number mRNAs, including those encoding the tubulins. The post‐induction degradation of induced tubulin mRNAs has been shown to differ from the consti‐tutive turnover pathway in two ways: (1) the rate of degradation is accelerated, and (2) degradation is prevented by inhibition of protein synthesis. In this report, it is shown that the post‐induction degradation of all deflagellation‐induced mRNAs examined is prevented by cycloheximide (CX), suggesting they all may be degraded via the same pathway. A cell‐free decay system has been developed to investigate the degradation pathway. At least two characteristics of tubulir mRNA degradation are reproducible in these extracts: (1) endogenous α‐tubulin mRNA is less stable than constitutive mRNAs in the same extract and (2) α‐tubulin mRNA in extracts prepared from CX‐treated cells (CX ex‐tracts) is significantly more stable than it is in extracts from untreated cells (control extracts). This indicates that the mechanism by which CX blocks rapid degradation of tubulin mRNA in vivo is not simply by preventing its translation and suggests the involvement of an altered trans‐factor. The difference in tubulin mRNA stability in the two extracts is maintained when the extracts are prepared under conditions that dissociate ribosomes from mRNPs, indicating intact polysome structure is not necessary. Tubulin mRNA‐containing polysomes isolated from control and CX extracts are equally stable when assayed alone. However, the poly‐somes from control extracts are more sensitive to exogenous RNAse treatment than are those from CX extracts, indicating a structural difference. There are no detectable differences in soluble factors that influence tubulin mRNA degradation rate between control and CX extracts; addition of excess soluble factors to either control or CX extracts does not alter the tubulin mRNA degradation in the extract, nor does a simple one‐to‐one combination of the two extracts result in stabilization or destabilization of the whole population of tubulin mRNAs in the mixture. The deflagellation‐induced mRNAs, as a group, are shown to be particularly susceptible to a nuclease activity in extracts, inhibitable by vanadyl ribonucleoside complexes, which does not appear to attack constitutive mRNAs. It is proposed that a structural difference in the tubulin mRNPs produced in the presence and absence of CX underlies their differences in stabilities, and that a common nuclease targets the induced flagellar protein mRNAs. © 1993 Wiley‐Liss, Inc.
More mog genes that influence the switch from spermatogenesis to oogenesis in the hermaphrodite germ line of Caenorhabditis elegans
Authors: Graham Patricia L. , Schedl Tim , Kimble Judith
Published: May 2005

The Caenorhobditis elegans XX animal possesses a hermaphrodite germ line, producing first sperm, then oocytes. In this paper, we report the genetic identification of five genes, mog‐2, mog‐3, mog‐4, mog‐5, and mog‐6, that influence the hermaphrodite switch from sper‐matogenesis to oogenesis. In mcg‐2‐mog‐6 mutants, spermatogenesis continues past the time at which hermaphrodites normally switch into oogenesis and no oocytes are observed. Therefore, in these mutants, germ cells are transformed from a female fate (oocyte) to a male fate (sperm). The fem‐3 gene is one of five genes that acts at the end of the germline sex determination pathway to direct spermatogenesis. Analyses of mog;fem‐3 double mutants suggest that the mog‐2‐mog‐6 genes act before fem‐3; thus these genes may be in a position to negatively regulate fem‐3 or one of the other terminal regulators of germline sex determination. Double mutants of fem‐3 and any one of the mog mutations make oocytes. Using these double mutants, we show that oocytes from any mog;fem‐3 double mutant are defective in their ability to support embryogenesis. This maternal effect lethality indicates that each of the mog genes is required for embryogenesis. The two defects in mog‐2‐mog‐6 mutants are similar to those of mog‐1: all six mog genes eliminate the sperm/oocyte switch in hermaphrodites and cause maternal effect lethality. We propose that the mog‐2‐mog‐6 mutations identify genes that act with mog‐1 to effect the sperm/oocyte switch. We further speculate that the mog‐1‐mog‐6 mutations all interfere with translational controls of fem‐3 and other maternal mRNAs. © 1993 Wiley‐Liss, Inc.
Sequence analysis of translationally controlled maternal mRNAs from Urechis caupo
Authors: Rosenthal Eric
Published: May 2005

Fertilization of Urechis coupo oocytes stimulates dramatic changes in the pattern of protein synthesis. This shift is brought about entirely through selective translation of the large pool of maternal mRNAs synthesized and stored during oogenesis. My laboratory has identified cDNA clones to more than 20 different Urechis maternal mRNAs. These have been used to determine whether the complementary mRNAs are translated in oocytes or embryos, and to analyze the polyad‐enylation status of the mRNAs at different stages. For 14 of the mRNAs, multiple, overlapping cDNA clones were isolated, and the complete sequence of the mRNA molecule was determined. Of these 14 mRNAs, half are from the subset that is translated in growing and full‐grown oocytes, but not in embryos. These 7 mRNAs have poly(A) tails before fertilization. The other 7 are from the subset that is not translated at any time before fertilization, and has very short poly(A) tails in oocytes. After fertilization these mRNAs are recruited onto polysomes and extensively polyadenylated. The sequence data from the two classes of maternal mRNAs was compared in an attempt to identify consensus sequences that could regulate translation directly, or indirectly, by controlling polyadenylation or secondary structure formation. Two features of the sequences correlate very well with the translation and polyadenylation of the different mRNAs‐the identity of the base immediately preceding the AUG start codon, and the presence of the sequences UUUUA and UUUUUA in the 3′ untranslated region. © 1993 Wiley‐Liss, Inc.
Antisense attenuation of Wnt‐1 and Wnt‐3a expression in whole embryo culture reveals roles for these genes in craniofacial, spinal cord, and cardiac morphogenesis
Authors: Augustine Karen , Liu Edison T. , Sadler T. W.
Published: May 2005

Wnt‐1 and Wnt‐3a proto‐on‐cogenes have been implicated in the development of midbrain and hindbrain structures. Evidence for such a role has been derived from in situ hybridization studies showing Wnt‐1 and ‐3a expression in developing cranial and spinal cord regions and from studies of mutant mice whose Wnt‐1 genes have undergone targeted disruption by homologous recombination. Wnt‐1 null mutants exhibit cranial defects but no spinal cord abnormalities, despite expression of the gene in these regions. The absence of spinal cord abnormalities is thought to be due to a functional compensation of the Wnt‐1 deficiency by related genes, a problem that has complicated the analysis of null mutants of other developmental genes as well. Herein, we describe the attenuation of Wnt‐1 expression using antisense oligonucleotide inhibition in mouse embryos grown in culture. We induce similar mid‐ and hindbrain abnormalities as those seen in the Wnt‐1 null mutant mice. Attentuation of Wnt‐1 expression was also associated with cardiomegaly resulting in hemostasis. These findings are consistent with the possibility that a subset of Wnt‐1 expressing cells include neural crest cells known to contribute to septation of the truncus arteriosus and to formation of the visceral arches. Antisense knockout of Wnt‐3a, a gene structurely related to Wnt‐1, targeted the forebrain and midbrain region, which were hy‐poplastic and failed to expand, and the spinal cord, which exhibited lateral outpocketings at the level of the forelimb buds. Dual antisense knockouts of Wnt‐1 and Wnt‐3a targeted all brain regions leading to incomplete closure of the cranial neural folds, and an increase in the number and severity of outpocketings along the spinal cord, suggesting that these genes complement one another to produce normal patterning of the spinal cord. The short time required to assess the mutant phenotype (2 days) and the need for limited sequence information of the target gene (20‐25 nu‐cleotides) make this antisense oligonucleotide/ whole embryo culture system ideal for testing the importance of specific genes and their interactions in murine embryonic development. © 1993 Wiley‐Liss, Inc.
Embryonic expression of the single Tribolium engrailed homolog
Authors: Brown Susan J. , Patel Nipam H. , Denell Robin E.
Published: May 2005

We have cloned and sequenced the single Tribolium homolog of the Drosophila engrailed gene. The predicted protein contains a homeobox and several domains conserved among all engrailed genes identified to date. In addition it contains several features specific to the invected homologs of Bombyx and Drosophila, indicating that these features most likely were present in the ancestral gene in the common ancestor of holometabolous insects. We used the cross‐reacting monoclonal antibody, 4D9, to follow the expression of the Engrailed protein during segmentation in Tribolium embryos. As in other insects, Engrailed accumulates in the nuclei of cells along the posterior margin of each segment. The first Engrailed stripe appears as the embryonic rudiment condenses. Then as the rudiment elongates into a germ band, Engrailed stripes appear in an anterior to posterior progression, just prior to morphological evidence of the formation of each segment. As in Drosophila (a long germ insect), expression of engrailed in Tribolium (classified as a short germ insect) is preceeded by the expression of several homologous segmentation genes, suggesting that similar genetic regulatory mechanisms are shared by diverse developmental types. © 1994 Wiley‐Liss, Inc.
Correlated evolution of the cis‐acting regulatory elements and developmental expression of the Drosophila Gld gene in seven species from the subgroup melanogaster
Authors: Ross Jennifer L. , Fong Peter P. , Cavener Douglas R.
Published: May 2005

The tissue‐specific expression patterns of glucose dehydrogenase (GLD) exhibit a high degree of inter specific variation in the adult reproductive tract among the species in the genus Drosophila. We chose to focus on the evolution of GLD expression and the evolution of the Gld promoter in seven closely related species in the mela‐nogaster subgroup as a means of elucidating the relationship of changes in cis‐acting regulatory elements in the Gld promoter region with changes in tissue‐specific expression. Although little variation in tissue‐specific patterns of GLD was found in nonreproductive tissues during development, a surprisingly high level of variation was observed in the expression of GLD in both developing and ma‐ture reproductive organs. In some cases this variation is correlated with changes in sequence elements in the Gld promoter which were previously shown to direct tissue‐specific expression in the reproductive tract. In particular D. teissieri adult males do not express GLD in their ejaculatory ducts, atypical of the melanogaster subgroup species. The Gld promoter region of D. teissieri specifically lacks all three of the TTAGA regulatory elements present in D. melanogaster. The TTAGA elements were previously shown to direct reporter gene expression to the ejaculatory duct. Together these data suggest the absence or presence of the TTAGA elements may be responsible for variation in the absence or presence of GLD in the ejaculatory duct among species. © 1994 Wiley‐Liss, Inc.
Quantitative genetics of butterfly wing color patterns
Authors: Paulsen Susan M.
Published: May 2005

Developmental processes exert their influence on the evolution of complex morphologies through the genetic correlations they engender between traits. Butterfly wing color patterns provide a model system to examine this connection between development and evolution. In butterflies, the nymphalid groundplan is a framework used to decompose complex wing patterns into their component pattern elements. The first goal of this work has been to determine whether the components of the nymphalid groundplan are the products of independent developmental processes. To test this hypothesis, the genetic correlation matrices for two species of butterflies, Precis coenia and Precis evarete, were estimated for 27 wing pattern characters. The second purpose was to test the hypothesis that the differentiation of serial homologs lowers their genetic correlations. The “eyespots” found serially repeated across the fore‐ and hindwing and on the dorsal and ventral wing surfaces provided an opportunity to test this hypothesis. The genetic correlation matrices of both species were very similar. The pattern of genetic correlation measured between the different types of pattern elements and between the homologous repeats of a pattern element supported the first hypothesis of developmental independence among the elements of the groundplan. The correlation pattern among the differentiated serial homologs was similarly found to support the second hypothesis: pairs of eyespots that had differentiated had lower genetic correlations than pairs that were similar in morphology. The implications of this study are twofold: First, the apparent developmental independence among the distinct elements of wing pattern has facilitated the vast diversification in morphology found in butterflies. Second, the lower genetic correlations betweendifferentiated homologs demonstrates that developmental constraints can in fact be broken. The extent to which genetic correlations readily change, however, remains unknown. © 1994 Wiley‐Liss, Inc.
Developmental quantitative genetic models of evolutionary change
Authors: Atchley William R. , Xu Shizhong , Vogl Claus
Published: May 2005

Discussions about evolutionary change in developmental processes or morphological structures are predicated on specific quantitative genetic models whose parameters predict whether evolutionary change can occur, its relative rate and direction, and if correlated change will occur in other related and unrelated structures. The appropriate genetic model should reflect the relevant genetical and developmental biology of the organisms, yet be simple enough in its parameters so that deductions can be made and hypotheses tested. As a consequence, the choice of the most appropriate genetic model for polygenically controlled traits is a complex tissue and the eventual choice of model is often a compromise between completeness of the model and computational expediency. Herein, we discuss several developmental quantitative genetic models for the evolution of development and morphology. The models range from the classical direct effects model to complex epigenetic models. Further, we demonstrate the algebraic equivalency of the Cowley and Atchley epigenetic model and Wagner's developmental mapping model. Finally, we propose a new multivariate model for continuous growth trajectories. The relative efficacy of these various models for understanding evolutionary change in developmental and morphological traits is discussed. © 1994 Wiley‐Liss, Inc.
Diverse programs of ascus development in pseudohomothallic species of Neurospora, Gelasinospora, and Podospora
Authors: Raju Namboori B. , Perkins David D.
Published: May 2005

Meiosis and ascospore development in the four‐spored pseudohomothallic ascomycetes Neurospora tetrasperma, Gelasinospora tetrasperma, Podospora anserina, and P. fefraspora have been reexamined, highlighting differences that reflect independent origins of the four‐spored condition in the different genera. In these species, as in the heterothallic eight‐spored N. crassa, fusion of haploid nuclei is followed directly by meiosis and a postmeiotic mitosis. These divisions take place within a single unpartitioned giant cell, the ascus, which attains a length of >0.1 mm before nuclei are enclosed by ascospore walls. Two basically different modes underlie the delivery of opposite mating type nuclei into each of the four ascospores in the different genera. In N. tefrasperma on the one hand, the mating type locus is closely centromere‐linked. Mating types therefore segregate at the first meiotic division. The second division spindles of N. tefrasperma overlap and are usually parallel to one another, in contrast to the their tandem arrangement in N. crassa. As a result, nonsister nuclei of opposite mating type are placed close together in each half‐ascus and a pair is enclosed in each ascospore. In the Podospora and Gelasinospora species on the other hand, the second‐division spindles are in tandem, with sister nuclei of opposite mating type associated as a pair in each half‐ascus. It is established for P. anserina and inferred for P. fetraspora and G. fefrasperma that a single reciprocal crossing over almost always occurs in the mating type‐centromere interval, ensuring that mating types segregate at the second meiotic division and that nuclei of opposite mating type are enclosed in each ascospore.

Other differences are also seen that are less fundamental. Neurospora tetrasperma differs from the other species in the orientation of chromosomes and spindle pole body plaques at interphase (I.) Third‐division spindles are oriented parallel to the ascus wall in Gelasinospora but across the ascus in Podospora and Neurospora. The two Podospora species differ from one another in nuclear behavior following mitosis in the young ascospores. In P. tefraspora, two of the four nuclei migrate into the tail cell, which degenerates, leaving one functional nucleus of each mating type. In P. anserina, by contrast, only one of the four nuclei moves into the tail cell, leaving the germinating ascospore with two functional nuclei of one mating type and one of the other.

The pseudohomothallic condition with its heterokaryotic vegetative phase has significant consequences for both the individual organism and the breeding system. Genetic controls of development and recombination are complex. Inbreeding is not obligatory. © 1994 WiIey‐Liss, Inc.
Ontogeny of gene expression in Pomoxis (pisces: Centrarchidae)
Authors: Epifanio John M. , Philipp David P.
Published: May 2005

The regulation of gene expression during embryogenesis was investigated in white and black crappie (Pomoxis spp.) and their reciprocal interspecific F1 hybrids. The schedule of morphological development and the timing of isozyme expression were compared among the two species and both reciprocal maternal half‐sibling F1 hybrids. Although absolute rates of morphological development differed in response to incubation temperature, relative rates of morphological development (normalized to the onset of retinal pigment deposition) were similar among all crosses. Furthermore, these relative rates were similar to those previously documented for other centrarchid species. To assess differences in ontogenetic patterns of gene expression among the crosses, we examined expression for 39 enzymeencoding loci. Expression was not detected in the embryos for 16 loci due to low or nonexistent activity. Enzymatic activity from eight other loci were continuously detected throughout embryogenesis as a result of maternal enzyme in the egg. However, 15 loci initiated expression during the early development period investigated (fertilization through yolk sac absorption). We observed temporal variability in expression of these 15 loci among the crosses, either in the form of differential expression between parental species or as disturbances in the ontogeny of expression in interspecific hybrids. Such variability in expression suggests that some of the gene regulating mechanisms have diverged since Pomoxis species shared a common ancestral genome. © 1994 Wiley‐Liss, Inc.
Zfy is transcribed in the normal mouse epididymis and in the XXSxr (“sex reversed”) testis
Authors: Mastrangelo Peter , Zwingman Theresa , Erickson Robert P. , Blecher Stan R.
Published: May 2005

The presence of the mutation Sex reversed (Sxr), a copy of a Y‐chromosomal segment that gets transferred to an X chromosome, causes the resulting XXSxr mice to develop as apparent males. However, several features of male sexual development are abnormal in these animals. The testes are small and aspermatogenic, and the epididymides lack the initial segment. Testes and epididymides show abnormalities of extracellular matrix. In this study we examined transcription of the conserved Y chromosomal gene Zfy, which has an X‐chromosomal homologue (Zfx). Northern blotting showed Zfy to be expressed in the testes of XXSxr animals, except for those that carry the coat‐marker gene Tabby (Ta), despite the lack of germ cells in XXSxr mice. Reverse transcription polymerase chain reaction (RT‐PCR) studies detected Zfy in mRNA in testes even when Ta was present. RT‐PCR also demonstrated Zfy transcription in epididymides of normal males, though not in XXSxr mice. Previous authors reported an absence of Zfy transcription in XXSxr testes; Zfy transcription in normal testes has been ascribed to germ cells. Our observation indicates that this idea requires re‐evaluation. The occurrence of Zfy transcription in the normal epididymis is similarly a novel finding that may help explain those aspects of epididymal development that occur in the absence of androgen. © 1994 Wiley‐Liss, Inc.
Developmentally regulated expression of fibroblast growth factor receptor genes and splice variants by murine embryonic stem and embryonal carcinoma cells
Authors: McDonald Fiona J. , Heath John K.
Published: May 2005

The expression of the four fibroblast growth factor receptor (FGF‐R) genes was examined in murine embryonic stem (ES) cells, embryonal carcinoma (EC) cells, and their differentiated derivatives. FGF‐R1 and FGF‐R4 were found to be expressed constitutively in all samples examined. The expression of FGF‐R2 and FGF‐R3 was, however found to increase significantly upon differentiation of both ES and EC cells. Examination of splice variants of the third immunoglobulin domain (Iglll) of the extracellular region of the FGF‐R2 revealed that whilst Iglllc transcripts were expressed upon ES cell differentiation, Iglllb transcripts (which confer specificity for the ligand FGF‐7) were expressed in both ES cells and their differentiated progeny. FGF‐R3 transcripts were also expressed in ES cells, but variont FGF‐R3 transcripts containing the Iglllb region were expressed upon differentiation. The findings suggest that the repertoire of FGF‐R expression in embryonic cell types is developmentally regulated at the level of both gene expression, and alternative splicing and different members of the FGF‐R family can exhibit distinct patterns of both gene and splice variant expression. © 1994 Wiley‐Liss, Inc.
Interactions between tassel seed genes and other sex determining genes in maize
Authors: Irish Erin E. , Langdale Jane A. , Nelson Timothy M.
Published: May 2005

The tassel seed mutations of maize cause sex reversal of the florets of the tassel, such that the normally staminate florets develop pistils. Although these mutations have been recognized for many years, little is known about how they act. We have tested the hypothesis that the tassel seed genes interact directly with each other and with other genes controlling sex determination in a single genetic pathway by the construction and analysis of double mutants. On the basis of the phenotypes of the double mutants, the tassel seed mutations were placed into two groups: ts1, ts2, Ts5 and ts4, Ts6. Both groups of tassel seed mutations were additive with the masculinizing mutation dwarf, indicating independent modes of action. Interactions of tassel seed mutations with silkless varied, allowing the ordering of the action of the various tassel seed mutations relative to silkless. Both groups of tassel seed mutations were epistatic with regard to sex expression to mutations that alter both architecture of the plant and distribution of male and female florets, Teopod 1, terminal ear, and teosinte branched. Thus, there are at least two separate genetic pathways that control the sex of florets in maize tassels. In addition, analysis of double mutants revealec that all tassel seed genes tested play a role in the regulation of flower morphogenesis as well as pistil suppression. © 1994 Wiley‐Liss, Inc.
Cell cycle mutation in Paramecium tetraurelia discriminates between sexual and vegetative functions
Authors: Adl Sina M. , Berger James D.
Published: May 2005

The temperature‐sensitive mutation cc1 blocks a number of cell cycle processes in Paramecium including macronuclear DNA synthesis, oral morphogenesis, and the later stages of micronuclear mitosis. Oral morphogenesis and micronuclear mitosis also occur in the sexual pathway. This study shows that cc1 cells can proceed through conjugation or autogamy under restrictive conditions; neither stomatogenesis nor micronuclear mitosis is blocked. Fertilization and macronuclear determination occur normally, but DNA synthesis in macronuclear anlagen is blocked. Therefore, this mutation discriminates between oral replacement during meiosis and vegetative prefission stomatogenesis, and between mitotic spindle elongation during the pregamic and postzygotic divisions and spindle elongation during the vegetative cell cycle. These results point to a fundamental regulatory difference between morphogenesis in the vegetative and sexual pathways. © 1994 Wiley‐Liss, Inc.
Action of the Tunicate locus on maize floral development
Authors: Langdale Jane A. , Irish Erin E. , Nelson Timothy M.
Published: May 2005

The co‐dominant Tunicate (Tu) mutation in maize causes nonreproductive structures in both the male and female inflorescences to be enlarged. This mutation also affects sex determination, permitting the development of pistils in the normally staminate tassel. In order to characterize the role of the normal tu gene product, we have analysed genetic interaction between Tu and other mutations that perturb specific stages of floral development. Synergistic interactions observed suggested that the tu product functions in at least three stages of floral development–determination of spikelet primordia, differentiation of non‐reproductive organs and pistil abortion in the tassel. © 1994 Wiley‐Liss, Inc.