bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biological and molecular correlates between induced dedifferentiation and spore germination in Dictyostelium
Authors: Chandrasekhar Anand , Ennis Herbert L. , Soll David R. 
Published: April 2021

ABSTRACT
When developing cultures of Dictyostelium discoideum are disaggregated at any time prior to cell wall formation and challenged to reinitiate development, amoebae will progress through the original sequence of morpho-genetic stages, but the second time through they will do so in roughly one-tenth the original time, a process known as ‘rapid recapitulation’. However, if disaggre-gated cells are suspended in nutrient medium, they enter a program of dedifferentiation during which they lose the capacity to rapidly recapitulate after an 80 minute lag period in a process known as ‘erasure’. Here we show that cells that have completed the morphogenetic program and emerge from spore coats in the process of germination have also erased. In addition, the germi-nation-specific 270 gene family is expressed during induced dedifferentiation in a unique fashion, and a germination-defective mutant exhibits a dramatic delay in erasure without concomitant defects in the program of gene regulation accompanying induced dedifferentia-tion. These results suggest for the first time that induced dedifferentiation and spore germination share some common processes in converting cells from a develop-mental to vegetative state.
CNS control of a critical period for peripheral induction of central neurons in the leech
Authors: Becker Tom , Macagno Eduardo R. 
Published: April 2021

ABSTRACT
Most midbody ganglia in the central nervous system (CNS) of the leech Hirudo medicinalis contain about 400 neurons. However, those in the fifth and sixth midbody segments (ganglia M5 and M6) are specialized for reproductive functions, and each contain several hundred additional small neurons. These neurons arise late in embryogenesis as a result of an innervation-dependent inductive interaction between the male genitalia and M5 and M6 and are therefore known as peripherally induced central (PIC) neurons. The results of a series of ablation and transplantation experiments show that the PIC neurons are induced during a 1 to 2 day period about midway in embryogenesis (E15). The male genitalia are not necessary for induction before or after this period, and their presence for only one day may be sufficient for the induction to take place. Heterochronic transplantation of male genitalia shows that the critical period of interaction is independent of the age of the inducing tissues. Since the inductive signal is available from E10 to postembryonic stages, both the beginning and the end of the inductive period are determined by the CNS, not the periphery.
Cell signals allow the expression of a pre-existent neural pattern in C. elegans
Authors: Waring David A. , Wrischnik Lisa , Kenyon Cynthia 
Published: April 2021

ABSTRACT
In C. elegans, a simple pattern develops within a row of epidermal precursor cells, V1-V6. One cell, V5, gives rise to a neuroblast called the postdeirid neuroblast, while the other V cells produce epidermal cells instead. Here we describe experiments suggesting that in order for V5 to produce the postdeirid it must be in close or direct contact with neighboring V cells. Signaling between V cells is required for the formation of the neuroblast; however, which of the V cells can make a postdeirid is not determined by these signals but rather by the action of the homeotic lin-22 and pal-1 genes. These genes prevent V cells in specific body regions from responding to intercellular signals and producing post-deirids. This is a clear example of cell signals playing a permissive rather than an instructive role in neuroblast induction.
Sequence and embryonic expression of the murine Hox-3.5 gene
Authors: Geada António M. C. , Gaunt Stephen J. , Azzawi May , Shimeld Sebastian M. , Pearce Jonathan , Sharpe Paul T. 
Published: April 2021

ABSTRACT
The murine Hox-3.5 gene has been mapped and linked genomically to a position 18 kb 3 of its most 5 locus neighbour, Hox-3.4, on chromosome 15. The sequence of the Hox-3.5 cDNA, together with the position of the gene within the locus, show it to be a paralogue of Hox-2.6, Hox-1.4 and Hox-4.2. The patterns of embryonic expression for the Hox-3.5 gene are examined in terms of three rules, proposed to relate a Hox gene’s expression pattern to its position within the locus. The anterior boundaries of Hox-3.5 expression in the hind-brain and prevertebral column lie anterior to those of Hox-3.4 and all other, more 5-located Hox-3 genes. Within the hindbrain, the Hox-3.5 boundary is seen to lie posterior to that of its paralogue, Hox-2.6, by a distance equal to about the length of one rhombomere. Patterns of Hox-3.5 expression within the oesophagus and spinal cord, but not the testis, are similar to those of other Hox-3 genes, Hox-3.3 and Hox-3.4.
Sensory mother cells are selected from among mitotically quiescent cluster of cells in the wing disc of Drosophila
Authors: Usui Kazuya , Kimura Ken-Ichi 
Published: April 2021

ABSTRACT
The large sensory bristles on the head and thorax of Drosophila are arranged in a precise pattern. Each bristle is formed by the progeny of a sensory mother cell (SMC) which is generated in the imaginal wing disc. The proneural genes ac and sc play an important role in the correct positioning of these SMCs by conferring to reproducibly located clusters of cells the competence to become SMCs. Indirect evidence suggested that the mitotic state of a cell could also play an important role in SMC positioning. In order to analyze the relation between the formation of SMC and the mitotic activity in the developing wing disc, we used BrdU immunolabeling to monitor the mitotic activity in an enhancertrap transformant line, A101, where the SMCs can be visualized. Our results indicate that SMCs arise from clusters of mitotically quiescent cells (MQC), and that the cell that becomes a SMC was itself arrested at the G2 stage of the cell cycle. The emergence of MQCs follows a precise temporal and spatial pattern which is not affected by the absence of the ac and/or sc genes. We propose that the reproducible emergence of MQCs could be an important factor in the formation of SMCs.
PAX8, a human paired box gene: isolation and expression in developing thyroid, kidney and Wilms’ tumors
Authors: Poleev Andrej , Fickenscher Helmut , Mundlos Stefan , Winterpacht Andreas , Zabel Bernhard , Fidler Andrew , Gruss Peter , Plachov Dimitrij 
Published: April 2021

ABSTRACT
Recent evidence indicates a crucial role for paired box genes in mouse and human embryogenesis. The murine Pax8 gene encodes a sequence-specific transcription factor and is expressed in the developing secretory system as well as in the developing and adult thyroid. This restricted expression pattern suggested involvement of the Pax8 gene in the morphogenesis of the above organs and prompted us to investigate the PAX8 gene in humans. In this report, we describe the isolation and characterization of PAX8 cDNAs from a human adult kidney cDNA library. An open reading frame of 450 amino acids contains the 128 amino acid paired domain at its amino-terminal end. The predicted human and mouse Pax8 proteins show 97.8% conservation and are identical in their paired domains. Two independent cDNA clones reveal differential splicing of the PAX8 transcripts resulting in the removal of a 63 amino acid serine-rich region from the carboxy end of the predicted Pax8 protein. The truncated Pax8 protein becomes more similar to the predicted murine Pax2 protein, that is also expressed during kidney development and lacks the serine rich region. RNAase protection analysis shows the presence of both PAX8 transcripts in human thyroid, kidney and five Wilms’ tumors. No truncated Pax8 transcripts could be detected in mouse kidney. In situ hybridization to sections of human embryonic and fetal kidney showed expression of PAX8 in condensed mesenchyme, comma-shaped and S-shaped bodies. In contrast, PAX2 expression was present mainly in the very early stages of differentiation, in the induced, condensing mesenchyme. This restricted expression pattern suggests a specific role for both genes during glomeruli maturation. Using somatic cell hybrids, we assigned the PAX8 gene to human chromosome 2. Comparative mapping data suggest a localization on distal 2q.
The expression of tissue and urokinase-type plasminogen activators in neural development suggests different modes of proteolytic involvement in neuronal growth
Authors: Sumi Y. , Dent M. A. R. , Owen D. E. , Seeley P. J. , Morris R. J. 
Published: April 2021

ABSTRACT
Tissue and urokinase-type plasminogen activators are serine proteases with highly restricted specificity, their best characterised role being to release the broad specificity protease plasmin from inactive plasminogen. It has frequently been suggested that these, and similar proteases, are involved in axonal growth and tissue remodelling associated with neural development. To help define what this role might be, we have studied the expression of the plasminogen activators in developing rat nervous tissue. Urokinase-type plasminogen activator mRNA is strongly expressed by many classes of neurons in peripheral and central nervous system. We have analysed its appearance in spinal cord and sensory ganglia, and found the mRNA is detectable by in situ hybridisation very early in neuronal development (by embryonic day 12.5), at a stage compatible with it playing a role in axonal or dendritic growth. Tissue plasminogen activator mRNA, on the other hand, is expressed only by cells of the floor plate in the developing nervous system, from embryonic day 10.5 and thereafter. Immunohistochemical and enzymatic analysis showed that active tissue plasminogen activator is produced by, and retained within, the floor plate. A mechanism is suggested by which high levels of tissue plasminogen activator produced by the stationary cells of the floor plate could influence the direction of growth of commissural axons as they pass through this midline structure.
Multiple gap junction genes are utilized during rat skin and hair development
Authors: Risek Boris , Klier F. George , Gilula Norton B. 
Published: April 2021

ABSTRACT
The expression of four different gap junction gene products ( α1, β1, β2, andβ 3) has been analysed during rat skin development and the hair growth cycle. Both α1 (C×43) and β2 (C×26) connexins were coexpressed in the undifferentiated epidermis. A specific, developmentally regulated elimination of β2 expression was observed in the periderm at E16. Coinciding with the differentiation of the epidermis, differential expression of α1 and β2 connexins was observed in the newly formed epidermal layers. α1 connexin was expressed in the basal and spinous layers, while β2 was confined to the differentiated spinous and granular layers. Large gap junctions were present in the basal layer, while small gap junctions, associated with many desmosomes, were typical for the differentiated layers. Although the distribution pattern for α1 and β2 expression remained the same in the neonatal and postnatal epidermis, the RNA and protein levels decreased markedly following birth. Hair follicle development was marked by expression of α1 connexin in hair germs at E16. Following 2 detection at E20, the expression increased for both α1 and β2 in developing follicles. A cell-type-specific expression was detected in the outer root sheath, in the matrix, in the matrixderived cells (inner root sheath, cortex and medulla) and in the dermal papilla. In addition, α1 was specifically expressed in the arrector pili muscle, while sebocytes expressed both α1 and β3 (C×31) connexin. β1 connexin (C×32) was not detected at any stage analysed. The results indicate that multiple gap junction genes contribute to epidermal and follicular morphogenesis. Moreover, based on the utilization of gap junctions in all living cells of the surface epidermis, it appears that the epidermis may behave as a large communication compartment that may be coupled functionally to epidermal appendages (hair follicles and sebaceous glands) via gap junctional pathways.
Lox2, a putative leech segment identity gene, is expressed in the same segmental domain in different stem cell lineages
Authors: Nardelli-Haefliger Denise , Shankland Marty 
Published: April 2021

ABSTRACT
The segmented tissues of the adult leech arise from a set of five, bilaterally paired embryonic stem cells via a stereotyped sequence of cell lineage. Individual segments exhibit unique patterns of cell differentiation, and pre-vious studies have suggested that each stem cell lineage establishes at least some aspects of its own segmental specificity autonomously. In this paper, we describe a putative leech segment identity gene, Lox2, and exam-ine its expression in the various stem cell lineages. Both sequence analysis and the segmental pattern of Lox2 expression suggest a specific homology to the fruitfly segment identity genes Ubx and abdA. In situ hybridization reveals a cellular accumulation of Lox2 RNA over a contiguous domain of 16 midbody segments (M6-M21), including postmitotic neurons, muscles and the differentiating genitalia. Lox2 transcripts were not detected at the stage when segment identities are first established, suggesting that Lox2 gene products may not be part of the initial specification process. Individual stem cell lineages were labeled by intracellular injection of fluorescent tracers, and single cell colocalization of lineage tracer and hybridization reaction product revealed expression of Lox2 RNA in the progeny of four different stem cells. The segmental domain of Lox2 RNA was very similar in the various stem cell lineages, despite the fact that some stem cells generate one founder cell/segment, whereas other stem cells generate two founder cells/segment.
Multiple cholinergic differentiation factors are present in footpad extracts: comparison with known cholinergic factors
Authors: Rao M. S. , Patterson Paul H. , Landis S. C. 
Published: April 2021

ABSTRACT
Sweat glands in rat footpads contain a neuronal differentiation activity that switches the phenotype of sym-pathetic neurons from noradrenergic to cholinergic during normal development in vivo. Extracts of developing and adult sweat glands induce changes in neuro-transmitter properties in cultured sympathetic neurons that mimic those observed in vivo. We have characterized further the factors present in the extract and com-pared their properties to those of known cholinergic fac-tors. When assayed on cultured rat sympathetic neurons, the major activities in footpad extracts from postnatal day 21 rat pups that induce choline acetyl-transferase (ChAT) and vasoactive intestinal peptide (VIP) and reduce catecholamines and neuropeptide Y (NPY) are associated with a soluble protein of 22 –26 ×103Mr and a pI of 5.0. These properties are similar to those of ciliary neurotrophic factor (CNTF). Moreover, the purified fraction from footpads has ciliary neurotrophic activity. Antibodies to CNTF that immunoprecipitate all differentiation activity from sciatic nerve extracts, a rich source of CNTF, immunoprecipitate 80% of the cholinergic activity in the footpad extracts, 50% of the VIP and 20% of the NPY activities. Neither CNTF protein nor CNTF mRNA, however, can be detected in immunoblot and northern analysis of footpads even though both CNTF protein and mRNA are evident in sciatic nerve. CNTF-immunoreactivity is associated with a sparse plexus of sensory fibers in the footpad but not with sweat glands or the Schwann cells associated with them. In addition, in situ hybridization studies with oligonucleotide probes failed to reveal CNTF mRNA in sweat glands. Comparison of the sweat gland differentiation activity with the cholinergic differentiation factor from heart cells (CDF; also known as leukemia inhibitory factor or LIF) suggests that most of the cholinergic activity in foot pads is biochemically distinct from CDF/LIF. Further, antibodies that block the activity of CDF/LIF purified from heart-cell-conditioned medium do not block the ChAT-inducing activity present in footpad extracts of postnatal day 8 animals. A differentiation factor isolated from skeletal muscle did not induce cholinergic properties in sympathetic neuron cultures and therefore is unlikely to be the cholinergic differentiation factor produced by sweat glands. Taken together, our data suggest that there are at least two differentiation molecules present in the extracts and that the major cholinergic activity obtained from footpads is related to, but distinct from, CNTF. The second factor remains to be characterized. In addition, CNTF associated with sensory fibers may make a minor contribution to the cholinergic inducing activity present in the extract.
The wingless product is required for cell proliferation in the Malpighian tubule anlage of Drosophila melanogaster
Authors: Skaer Helen , Arias Alfonso Martinez 
Published: April 2021

ABSTRACT
Cell division in the Malpighian tubules of Drosophila melanogaster depends on the presence of a specialised cell at the tip of each tubule (Skaer, H. le B (1989) Nature 342, 566 –569). Here we show that cell division also depends on the normal expression of the segment polarity gene, wingless. The pattern of wingless RNA and protein in developing tubules is consistent with a requirement for wingless for cell division. Analysis of the temporal requirement for wingless using a temperature-sensitive allele confirms that the normal expression of wingless is necessary during cell proliferation in the Malpighian tubules. Over-expression of the gene, induced in a stock containing the wg gene under the control of a heat-shock promoter, results in super-numerary cells in the tubules. We discuss the role of wingless in the cell interactions that govern cell division in the Malpighian tubules.
Expression patterns of vHNF1 and HNF1 homeoproteins in early postimplantation embryos suggest distinct and sequential developmental roles
Authors: Cereghini Silvia , Ott Marie-Odile , Power Susan , Maury Martine 
Published: April 2021

ABSTRACT
The homeoproteins HNF1 (LFB1/HNF1-A) and vHNF1 (LFB3/HNF1β) interact with an essential control element of a group of liver-specific genes. During development, these putative target genes are initially expressed in the visceral endoderm of the yolk sac and subsequently in fetal liver. To assess the possible involvement of HNF1 and/or vHNF1 as transcriptional regulators in the early steps of visceral endoderm differentiation, we have analyzed the expression pattern of both factors both in vitro during differentiation of murine F9 embryonal carcinoma cells and in vivo during early postim-plantation mouse development. We show here that differentiation of F9 cells into either visceral or parietal endoderm is accompanied by a sharp induction in vHNF1 mRNA and protein. By contrast, only low levels of aberrantly sized HNF1 transcripts, but not DNA-binding protein, are found in F9 cells and its differentiated derivatives. At 6 – 7.5 days of gestation, high levels of vHNF1 mRNA are present in the visceral extraem-bryonic endoderm, which co-localize with transcripts of the transthyretin gene. HNF1 transcripts are first detected in the yolk sac roughly two embryonic days later, after the developmental onset of transcription of target genes. As development proceeds, discrepancies are observed between the level of transcripts of both vHNF1 and HNF1 and their respective nuclear binding proteins, notably in the yolk sac and embryonic kidney. In addition, we show that two alternative spliced isoforms of vHNF1 mRNA, vHNF-A and vHNF1-B, are expressed in both embryonic and adult tissues. Taken together, these data suggest that vHNF1 participates as a regulatory factor in the initial transcriptional activation of the target genes in the visceral endoderm of the yolk sac, whereas the later appearance of HNF1 could be required for maintenance of their expression. Our results also provide evidence of a posttranscriptional level of control of vHNF1 and HNF1 gene expression during development, in addition to the spatial restriction in transcription.
Expression of the zinc finger gene Gli3 is affected in the morphogenetic mouse mutant extra-toes (Xt)
Authors: Schimmang Thomas , Lemaistre Marianne , Vortkamp Andrea , Rüther Ulrich 
Published: April 2021

ABSTRACT
Genetic analysis and homology between the phenotypic alterations of the human Greig Cephalopolysyndactyly Syndrome (GCPS) and the mouse mutant extra-toes (Xt) have suggested a dominant mutation in the same gene of both species. Recently, the GLI3 gene, a member of the Krüppel-related zinc finger genes, has been proposed as a candidate gene for GCPS. We examined the expression of the mouse Gli3 gene in both Xt mutant animals and during normal mouse development. Northern and RNAase protection analysis of embryos revealed that Gli3 expression was reduced about 50% in heterozygous Xt/+ mice and completely absent in homozygous Xt/Xt mice. In addition, in situ analysis of wild-type mice documented Gli3 expression in the developing limb and brain, structures affected in Xt mutant mice. This pattern suggests an important function of the Gli3 gene during morphogenesis.
Apical ridge dependent and independent mesodermal domains of GHox-7 and GHox-8 expression in chick limb buds
Authors: Ros Maria A. , Lyons Gary , Kosher Robert A. , Upholt William B. , Coelho Caroline N. D. , Fallon John F. 
Published: April 2021

ABSTRACT
The homeobox-containing genes GHox-7 and GHox-8 have been proposed to play fundamental roles in limb development. The expression of GHox-8, by the apical ridge cells, and GHox-7, in the subridge mesoderm, suggests the involvement of these two genes in limb out-growth and proximo-distal pattern formation. A straightforward way to test this is to remove the apical ridge. Here we report the relationship between the mesodermal expression of GHox-7 and GHox-8 and the apical ectodermal ridge in the chick limb bud. The data from ridge removal experiments indicate that there are at least two domains of GHox-7 expression in the apical limb bud mesoderm. The posterior subridge GHox-7 domain in the progress zone requires the influence of the apical ridge for continued expression, while the anterior GHox-7 domain continues expression after ridge removal. Posterior subridge mesoderm is exquisitely sensitive to the loss of the ridge in that GHox-7 expression by these cells is reduced in only two hours and undetectable by three hours after ridge removal. It would appear that one of the ways progress zone cells respond to the apical ridge signal is by expressing GHox-7.The loss of ridge influence whether by growth at the apex or by ridge removal is followed by an unusually rapid decline in detectable GHox-7 transcripts. Maintenance of GHox-8 expression by the anterior mesoderm appears to be independent of the presence of the apical ridge. Finally our data indicate that neither GHox-7 nor GHox-8 transcripts need be detectable in the cells that are induced to die after apical ridge removal.