bluuebunny/crossref_metadata_2025 huggingface dataset:
A pulmonary ligament approach for portal robotic segmentectomy of the lateral and posterior basal segments: a case report
Authors: Mitsuboshi Shota , Shidei Hiroaki , Koen Akihiro , Maeda Hideyuki , Aoshima Hiroe , Isaka Tamami , Kanzaki Masato
Published: April 2021

Background

Thoracoscopic segmentectomy of the lateral and posterior basal segments is extremely technically challenging. Appropriate segmentectomy requires exposure and recognition of the branches of the bronchi and pulmonary vessels deep in the lung parenchyma. Although various approaches for these segmentectomies have been reported, the use of a pulmonary ligament approach is rational because it does not require any interlobar separation. Here, we report a successful case of portal robotic segmentectomy of the lateral and posterior basal segments through the pulmonary ligament approach.

Case presentation

A 60-year-old Japanese man with a history of low anterior resection for rectal cancer was referred to our department because of a lung nodule. His chest computed tomography revealed a 15-mm tumor in the left posterior basal bronchus. Robotic left S9–10 segmentectomy through the pulmonary ligament was performed with five-port incisions.

Conclusions

An extremely technically challenging thoracoscopic segmentectomy of the lateral and posterior basal segments was performed through the pulmonary ligament using a robotic surgical system.
Abdominal fat ratio estimation equation by abdominal type in elderly women
Authors: Lee Jooyeon , Park Jinhee
Published: April 2021

This study was conducted to define the abdomen types of Korean elderly women and to develop an abdominal fat ratio (AFR) estimation equation using key body measurements and indexes that well represented the body type characteristics of elderly women. An analysis was performed of the correlations between the individual obesity-related measurements and index items to explain the body shape characteristics and obesity trends in elderly women. To derive the equation for estimating the AFR of elderly women, the abdominal types of elderly women were classified, and then, the distribution of each type was investigated. Then, a simple regression analysis was performed in which the dependent variable is predicted by using a single predictor. The AFR and WHtR (Waist-Height Ratio) showed a higher correlation with the obesity-related measurement items and indexes; thus, an equation was derived that enables the estimation of the AFR using simple body measurements. Additionally, the morphological differences of the various abdomen types were analyzed to provide the trends of the abdomen types depending on the AFR in the elderly. This new model for estimating abdominal fat percentage developed in the present study is significant in that it uses relatively easy-to-obtain anthropometric measures like height and waist circumference. The results of the present study demonstrated the relationship between WHtR, which not only well reflects elderly obesity but is also closely related to the prevalence of obesity in the elderly. This finding suggests that the shape of the abdomen will serve as a potential health indicator in the future.
Effect of prophylactic administration of antipyretics on the immune response to pneumococcal conjugate vaccines in children: a systematic review
Authors: Koufoglou Eleni , Kourlaba Georgia , Michos Athanasios
Published: April 2021

Background

Prophylactic administration of antipyretics at the time of immunization seems to decrease some side effects, however reduced immune responses have been reported in some studies. This systematic review aimed to investigate the effect of prophylactic use of antipyretics on the immune response following administration of pneumococcal conjugate vaccines (PCVs).

Methods

A systematic review of randomized controlled trials and observational studies concerning the immune response to PCVs after antipyretic administration was performed up to November 2020 in the electronic databases of Pubmed and Scopus.

Results

Of the 3956 citations retrieved, a total of 5 randomized control trials including 2775 children were included in the review. Included studies were referred to PCV10 (3 studies), PCV7 and PCV13 (one study each). The prophylactic administration of paracetamol decreased the immune response to certain pneumococcal serotypes in all included studies. The effect was more evident following primary vaccination and with immediate administration of paracetamol. Despite the reductions in antibody geometric mean concentrations, a robust memory response was observed following the booster dose. Besides, antibody titers remained above protective levels in 88–100% of participants. The use of ibuprofen, that was evaluated in two studies, did not seem to affect the immunogenicity of PCVs .

Conclusion

Although the reviewed studies had significant heterogeneity in design, paracetamol administration seems to affect the immune response for certain serotypes. The clinical significance of reduced immunogenicity especially before booster dose needs further investigation.
Brief cytochalasin-induced disruption of microfilaments during a critical interval in 1-cell C. elegans embryos alters the partitioning of developmental instructions to the 2-cell embryo
Authors: Hill David P. , Strome Susan
Published: April 2021

We are investigating the involvement of the microfilament cytoskeleton in the development of early Caenor-habditis elegans embryos. We previously reported that several cytoplasmic movements in the zygote require that the microfilament cytoskeleton remain intact during a narrow time interval approximately three-quarters of the way through the first cell cycle. In this study, we analyze the developmental consequences of brief, cytochalasin D-induced microfilament disruption during the 1-cell stage. Our results indicate that during the first cell cycle microfilaments are important only during the critical time interval for the 2-cell embryo to undergo the correct pattern of subsequent divisions and to initiate the differentiation of at least 4 tissue types. Disruption of microfilaments during the critical interval results in aberrant division and P-granule segregation patterns, generating some embryos that we classify as ‘reverse polarity’, ‘anterior duplication’, and ‘posterior duplication’ embryos. These altered patterns suggest that microfilament disruption during the critical interval leads to the incorrect distribution of developmental instructions responsible for early pattern formation. The strict correlation between unequal division, unequal germ-granule partitioning, and the generation of daughter cells with different cell cycle periods observed in these embryos suggests that the three processes are coupled. We hypothesize that (1) an ‘asymmetry determinant’, normally located at the posterior end of the zygote, governs asymmetric cell division, germ-granule segregation, and the segregation of cell cycle timing elements during the first cell cycle, and (2) the integrity or placement of this asymmetry determinant is sensitive to microfilament disruption during the critical time interval.
Visualization of the endoplasmic reticulum in living buds and branches of the moss Funaria hygrometrica by confocal laser scanning microscopy
Authors: Mccauley M. Michele , Hepler Peter K.
Published: April 2021

Caulonemata of the moss Funaria hygrometrica were vitally stained with the fluorescent, lipophilic carbocyanine dye DiOC6(3) and examined via confocal laser scanning microscopy. Although DiOC6 (3) stained nearly all of the organelles, cortical endoplasmic reticulum (ER) could be resolved under favorable conditions and appeared as a network of irregular polygons, interspersed with lamellar cisternae in some cell types. The pattern of cortical ER was examined first during side initial formation and then in young branches and buds. The ER network extends into the outgrowth of a developing side initial, keeping pace with elongation of the outgrowth. Prior to the cell division that cuts off the outgrowth from the underlying cell, the network in the outgrowth becomes tighter, i.e. the polygons become smaller. If the side initial develops as a branch, this somewhat tighter ER network is maintained in the tip-growing side branch. If the side initial develops as a bud, dramatic changes in both the configuration and the quantity of the ER network occur. Coincident with the apical swelling that marks the first visible sign of bud formation, the network becomes increasingly tighter until eventually the polygonal configuration is barely discernible. The increased coverage of the bud cortex by the ER network demonstrates that a significant increase in the quantity of membranes also takes place during bud formation in Funaria.
Hox-2.3 upstream sequences mediate lacZ expression in intermediate mesoderm derivatives of transgenic mice
Authors: Kress Chantal , Vogels Ronald , Graaff Wim De , Bonnerot Claire , Meijlink Frits , Nicolas Jean-François , Deschamps Jacqueline
Published: April 2021

The mouse Hox-2.3 gene contains an Antp-like homeobox sequence and is expressed in a spatially restricted anteroposterior domain during development. To study the molecular basis of this differential gene regulation, we set out to characterize the cis-regulatory elements mediating Hox-2.3 expression during embryogenesis. We show that a fragment extending 1316 base pairs (bp) upstream of the transcription start site, thus corresponding to the Hox-2.4/Hox-2.3 intergenic sequences is capable of mediating luciferase gene transcription in transfected cells in vitro and lacZ expression in transgenic mice. The β-galactosidase-staining pattern in embryos was found to be strikingly similar to the Hox-2.3 in situ hybridization pattern in intermediate mesoderm derivatives: high levels of both Hox-2.3 transcripts and β-galactosidase activity were found in the mesonephric duct-derived epithelium of the meso- and metanephric kidney and associated ducts, from the time these structures first appeared on throughout development. The transgene apparently lacks sequences needed for correct Hox-2.3 expression in somitic and lateral plate mesoderm and in neurectoderm. These results document the involvement of distinct regulatory elements in Hox gene expression in subsets of cells with distinct developmental fate, situated at similar positions along the anteroposterior axis of the embryo.
Organogenesis and pattern formation in the mouse: RNA distribution patterns suggest a role for Bone Morphogenetic Protein-2A (BMP-2A)
Authors: Lyons Karen M. , Pelton Ron W. , Hogan Brigid L. M.
Published: April 2021

Bone morphogenetic protein-2A (BMP-2A) is a member of the transforming growth factor β (TGF β) gene family that has been implicated in cartilage and bone formation. Here we use in situ hybridization to show that BMP-2A RNA is expressed in a variety of embryonic epithelial and mesenchymal tissues outside of the developing skeletal system, including cell populations known to play important roles in morphogenesis. Thus, high levels of transcripts are found in developing limb buds (ventral ectoderm and apical ectodermal ridge), heart (myocardium of the atrioventricular canal), whisker follicles (ectodermal placodes, hair matrix and precortex cells), tooth buds (epithelial buds, dental papilla and odontoblasts), and craniofacial mesenchyme, as well as a number of other sites. The expression patterns of BMP-2A are different from those of TGF β-1, -2 and -3, and this is illustrated in detail in the developing whisker follicles. These results suggest that BMP-2A plays multiple roles in morphogenesis and pattern formation in the vertebrate embryo.
Identification of a novel growth factor with transforming activity secreted by individual chick embryos
Authors: Smith Janet , McLachlan John C.
Published: April 2021

Previously we have developed a microassay for anchorage independent growth (AIG) of fibroblasts in soft agar, which can detect very small quantities of transforming growth factors (TGFs). Using this assay, we have shown that small pieces of dissected chick embryo tissue will stimulate AIG of both NR6 and NRK 49f cells, and that this property can be used to map production of growth factors with transforming activity in individual early embryos. We now show that this activity can be transferred to conditioned medium (CM) prepared using chick embryo tissue. Using two cell lines with differential responsiveness to TGFs, and by coincubating normal and heat-treated CM with trypsin, Con-A and neutralising antibodies, we show that CM contains at least two different growth factors with transforming activity. One of these is heat-stable, and stimulates colony formation in NRK 49f cells in the presence of EGF, but not in its absence. This activity corresponds to a TGFβ-like molecule. The other component is a heat-labile glycoprotein, which has TGFα-like properties, but does not appear to behave like known TGFs with these properties. It therefore appears to be a novel growth factor. Both activities are present from the intermediate primitive streak stage of development.
The effects of embryonic retinal neurons on neural crest cell differentiation into Schwann cells
Authors: Smith-Thomas L. C. , Johnson A. R. , Fawcett J. W.
Published: April 2021

Amongst the many cell types that differentiate from migratory neural crest cells are the Schwann cells of the peripheral nervous system. While it has been demonstrated that Schwann cells will not fully differentiate unless in contact with neurons, the factors that cause neural crest cells to enter the differentiative pathway that leads to Schwann cells are unknown. In a previous paper (Development 105: 251, 1989), we have demonstrated that a proportion of morphologically undifferentiated neural crest cells express the Schwann cell markers 217c and NGF receptor, and later, as they acquire the bipolar morphology typical of Schwann cells in culture, express S-100 and laminin. In the present study, we have grown axons from embryonic retina on neural crest cultures to see whether this has an effect on the differentiation of neural crest cells into Schwann cells. After 4 to 6 days of co-culture, many more cells had acquired bipolar morphology and S-100 staining than in controls with no retinal explant, and most of these cells were within 200 μm of an axon, though not necessarily in contact with axons. However, the number of cells expressing the earliest Schwann cell markers 217c and NGF receptor was not affected by the presence of axons. We conclude that axons produce a factor, which is probably diffusible, and which makes immature Schwann cells differentiate. The factor does not, however, influence the entry of neural crest cells into the earliest stages of the Schwann cell differentiative pathway.
Differentiation of tropomyosin-containing myofibrils in cleavage-arrested ascidian zygotes expressing acetylcholinesterase
Authors: Crowther Robert J. , Meedel Thomas H. , Whittaker J. R.
Published: April 2021

Two muscle differentiation programs, acetylcholinesterase and tropomyosin-containing filaments and fibrils, occur together in the same cleavage-arrested zygotes (1-celled) of the ascidian Ciona intestinalis. Coexpression in such undivided but developing ‘embryos’ is consistent with the idea that separate elements of muscle differentiation are related at some regulatory level, perhaps through a single multi-gene regulatory factor. Fertilized Ciona eggs were exposed to cytochalasin B for 20 h and then briefly reacted histochemically for acetylcholinesterase activity. Strongly reacting specimens were selected and processed for transmission electron microscopy to reveal regions of muscle ultrastructure. Every acetylcholinesterase-reactive zygote tested contained muscle contractile elements; no example lacking acetylcholinesterase was found with myofilaments and myofibrils. As demonstrated by immunogold labelling, a polyclonal antibody to tropomyosin from Ciona adult body wall reacted differentially with the presumed ultrastructural muscle elements in cleavage-arrested zygotes. Site-specific reactions were also observed in larval tail muscle and the siphon muscles of postmetamorphic zooids.
Engrailed homeoprotein secretion is a regulated process
Authors: Maizel Alexis , Tassetto Michel , Filhol Odile , Cochet Claude , Prochiantz Alain , Joliot Alain
Published: April 2021

Chicken Engrailed 2 homeoprotein is transported between cells in culture. This intercellular transfer is based on unconventional secretion and internalisation mechanisms: Engrailed 2 has access to vesicles but lacks a signal sequence for secretion and is internalised by a non-endocytic process. We show that phosphorylation of a serine-rich domain within Engrailed 2 by the protein kinase CK2 specifically inhibits Engrailed 2 secretion. The availability of the serine-rich domain to CK2 is highly increased when it is displaced from its normal position to the C terminus of Engrailed 2, leading to a constitutive blockage of Engrailed 2 intercellular transfer. This indicates that intercellular transfer of Engrailed 2 is a highly regulated process.
The role of TGFβ signaling in the formation of the dorsal nervous system is conserved betweenDrosophilaand chordates
Authors: Rusten Tor Erik , Cantera Rafael , Kafatos Fotis C. , Barrio Rosa
Published: April 2021

Transforming growth factor β signaling mediated by Decapentaplegic and Screw is known to be involved in defining the border of the ventral neurogenic region in the fruitfly. A second phase of Decapentaplegic signaling occurs in a broad dorsal ectodermal region. Here, we show that the dorsolateral peripheral nervous system forms within the region where this second phase of signaling occurs. Decapentaplegic activity is required for development of many of the dorsal and lateral peripheral nervous system neurons. Double mutant analysis of the Decapentaplegic signaling mediator Schnurri and the inhibitor Brinker indicates that formation of these neurons requires Decapentaplegic signaling, and their absence in the mutant is mediated by a counteracting repression by Brinker. Interestingly, the ventral peripheral neurons that form outside the Decapentaplegic signaling domain depend on Brinker to develop. The role of Decapentaplegic signaling on dorsal and lateral peripheral neurons is strikingly similar to the known role of Transforming growth factor β signaling in specifying dorsal cell fates of the lateral (later dorsal) nervous system in chordates (Halocythia, zebrafish, Xenopus, chicken and mouse). It points to an evolutionarily conserved mechanism specifying dorsal cell fates in the nervous system of both protostomes and deuterostomes.
Elbow and Noc define a family of zinc finger proteins controlling morphogenesis of specific tracheal branches
Authors: Dorfman Ruslan , Glazer Lillian , Weihe Ulrich , Wernet Mathias F. , Shilo Ben-Zion
Published: April 2021

The elbow (elB) gene encodes a conserved nuclear protein with a single zinc finger. Expression of ElB is restricted to a specific subset of tracheal cells, namely the dorsal branch and the lateral trunks. Stalled or aberrant migration of these branches is observed in elB mutant embryos. Conversely, ElB misexpression in the trachea gave rise to absence of the visceral branch and an increase in the number of cells forming the dorsal branch. These results imply that the restricted expression of ElB contributes to the specification of distinct branch fates, as reflected in their stereotypic pattern of migration. As elB loss-of-function tracheal phenotypes are reminiscent of defects in Dpp signaling, the relationship between ElB and the Dpp pathway was examined. By using pMad antibodies that detect the activation pattern of the Dpp pathway, we show that Dpp signaling in the trachea is not impaired in elB mutants. In addition, expression of the Dpp target gene kni was unaltered. The opposite is true as well, because expression of elB is independent of Dpp signaling. ElB thus defines a parallel input, which determines the identity of the lateral trunk and dorsal branch cells. No ocelli (Noc) is the Drosophila protein most similar to ElB. Mutations in noc give rise to a similar tracheal phenotype. Noc is capable of associating with ElB, suggesting that they can function as a heterodimer. ElB also associates with the Groucho protein, indicating that the complex has the capacity to repress transcription of target genes. Indeed, in elB or noc mutants, expanded expression of tracheal branch-specific genes was observed.
Mixl1is required for axial mesendoderm morphogenesis and patterning in the murine embryo
Authors: Hart Adam H. , Hartley Lynne , Sourris Koula , Stadler Elizabeth S. , Li Ruili , Stanley Edouard G. , Tam Patrick P. L. , Elefanty Andrew G. , Robb Lorraine
Published: April 2021

In Xenopus, the Mix/Bix family of homeobox genes has been implicated in mesendoderm development. Mixl1 is the only known murine member of this family. To examine the role of Mixl1 in murine embryogenesis, we used gene targeting to create mice bearing a null mutation of Mixl1. Homozygous Mixl1 mutant embryos can be distinguished from their littermates by a marked thickening of the primitive streak. By the early somite stage, embryonic development is arrested, with the formation of abnormal head folds, foreshortened body axis, absence of heart tube and gut, deficient paraxial mesoderm, and an enlarged midline tissue mass that replaces the notochord. Development of extra-embryonic structures is generally normal except that the allantois is often disproportionately large for the size of the mutant embryo. In chimeras, Mixl1–/– mutant cells can contribute to all embryonic structures, with the exception of the hindgut, suggesting that Mixl1 activity is most crucial for endodermal differentiation. Mixl1 is therefore required for the morphogenesis of axial mesoderm, the heart and the gut during embryogenesis.
Ephrin-B ligands play a dual role in the control of neural crest cell migration
Authors: Santiago Alicia , Erickson Carol A.
Published: April 2021

Little is known about the mechanisms that direct neural crest cells to the appropriate migratory pathways. Our aim was to determine how neural crest cells that are specified as neurons and glial cells only migrate ventrally and are prevented from migrating dorsolaterally into the skin, whereas neural crest cells specified as melanoblasts are directed into the dorsolateral pathway. Eph receptors and their ephrin ligands have been shown to be essential for migration of many cell types during embryonic development. Consequently, we asked if ephrin-B proteins participate in the guidance of melanoblasts along the dorsolateral pathway, and prevent early migratory neural crest cells from invading the dorsolateral pathway. Using Fc fusion proteins, we detected the expression of ephrin-B ligands in the dorsolateral pathway at the stage when neural crest cells are migrating ventrally. Furthermore, we show that ephrins block dorsolateral migration of early-migrating neural crest cells because when we disrupt the Eph-ephrin interactions by addition of soluble ephrin-B ligand to trunk explants, early neural crest cells migrate inappropriately into the dorsolateral pathway. Surprisingly, we discovered the ephrin-B ligands continue to be expressed along the dorsolateral pathway during melanoblast migration. RT-PCR analysis, in situ hybridisation, and cell surface-labelling of neural crest cell cultures demonstrate that melanoblasts express several EphB receptors. In adhesion assays, engagement of ephrin-B ligands to EphB receptors increases melanoblast attachment to fibronectin. Cell migration assays demonstrate that ephrin-B ligands stimulate the migration of melanoblasts. Furthermore, when Eph signalling is disrupted in vivo, melanoblasts are prevented from migrating dorsolaterally, suggesting ephrin-B ligands promote the dorsolateral migration of melanoblasts. Thus, transmembrane ephrins act as bifunctional guidance cues: they first repel early migratory neural crest cells from the dorsolateral path, and then later stimulate the migration of melanoblasts into this pathway. The mechanisms by which ephrins regulate repulsion or attraction in neural crest cells are unknown. One possibility is that the cellular response involves signalling to the actin cytoskeleton, potentially involving the activation of Cdc42/Rac family of GTPases. In support of this hypothesis, we show that adhesion of early migratory cells to an ephrin-B-derivatized substratum results in cell rounding and disruption of the actin cytoskeleton, whereas plating of melanoblasts on an ephrin-B substratum induces the formation of microspikes filled with F-actin.
Morphological boundary forms by a novel inductive event mediated by Lunatic fringe and Notch during somitic segmentation
Authors: Sato Yuki , Yasuda Kunio , Takahashi Yoshiko
Published: April 2021

Boundary formation plays a central role in differentiating the flanking regions that give rise to discrete tissues and organs during early development. We have studied mechanisms by which a morphological boundary and tissue separation are regulated by examining chicken somite segmentation as a model system. By transplanting a small group of cells taken from a presumptive border into a non-segmentation site, we have found a novel inductive event where posteriorly juxtaposed cells to the next-forming border instruct the anterior cells to become separated and epithelialized. We have further studied the molecular mechanisms underlying these interactions by focusing on Lunatic fringe, a modulator of Notch signaling, which is expressed in the region of the presumptive boundary. By combining DNA in ovo electroporation and embryonic transplantation techniques we have ectopically made a sharp boundary of Lunatic fringe activity in the unsegmented paraxial mesoderm and observed a fissure formed at the interface. In addition, a constitutive active form of Notch mimics this instructive phenomenon. These suggest that the boundary-forming signals emanating from the posterior border cells are mediated by Notch, the action of which is confined to the border region by Lunatic fringe within the area where mRNAs of Notch and its ligand are broadly expressed in the presomitic mesoderm.
Drumstick is a zinc finger protein that antagonizes Lines to control patterning and morphogenesis of theDrosophilahindgut
Authors: Green Ryan B. , Hatini Victor , Johansen Katherine A. , Liu Xue-Jun , Lengyel Judith A.
Published: April 2021

Elongation of the Drosophila embryonic hindgut epithelium occurs by a process of oriented cell rearrangement requiring the genes drumstick (drm) and lines (lin). The elongating hindgut becomes subdivided into domains – small intestine, large intestine and rectum – each characterized by a specific pattern of gene expression dependent upon normal drm and lin function. We show that drm encodes an 81 amino acid (10 kDa) zinc finger protein that is a member of the Odd-skipped family. drm expression is localized to the developing midgut-hindgut junction and is required to establish the small intestine, while lin is broadly expressed throughout the gut primordium and represses small intestine fate. lin is epistatic to drm, suggesting a model in which localized expression of drm blocks lin activity, thereby allowing small intestine fate to be established. Further supporting this model, ectopic expression of Drm throughout the hindgut produces a lin phenotype. Biochemical and genetic data indicate that the first conserved zinc finger of Drm is essential for its function. We have thus defined a pathway in which a spatially localized zinc finger protein antagonizes a globally expressed protein, thereby leading to specification of a domain (the small intestine) necessary for oriented cell rearrangement.
The different components of a multisubunit cell number-counting factor have both unique and overlapping functions
Authors: Brock Debra A. , Hatton R. Diane , Giurgiutiu Dan-Victor , Scott Brenton , Ammann Robin , Gomer Richard H.
Published: April 2021

Dictyostelium aggregation streams break up into groups of 103 to 2×104 cells. The cells sense the number of cells in a stream or group by the level of a secreted counting factor (CF). CF is a complex of at least 5 polypeptides. When the gene encoding countin (one of the CF polypeptides) was disrupted, the cells could not sense each other’s presence, resulting in non-breaking streams that coalesced into abnormally large groups. To understand the function of the components of CF, we have isolated cDNA sequences encoding a second component of CF, CF50. CF50 is 30% identical to lysozyme (but has very little lysozyme activity) and contains distinctive serine-glycine motifs. Transformants with a disrupted cf50 gene, like countin– cells, form abnormally large groups. Addition of recombinant CF50 protein to developing cf50– cells rescues their phenotype by decreasing group size. Abnormalities seen in aggregating countin– cells (such as high cell-cell adhesion and low motility) are also observed in the cf50– cells. Western blot analysis of conditioned medium sieve column fractions showed that the CF50 protein is present in the same fraction as the 450 kDa CF complex. In the absence of CF50, secreted countin is degraded, suggesting that one function of CF50 may be to protect countin from degradation. However, unlike countin– cells, cf50– cells differentiate into an abnormally high percentage of cells expressing SP70 (a marker expressed in a subset of prespore cells), and this difference can be rescued by exposing cells to recombinant CF50. These observations indicate that unlike other known multisubunit factors, CF contains subunits with both overlapping and unique properties.
Translational repression by MSY4 inhibits spermatid differentiation in mice
Authors: Giorgini Flaviano , Davies Holly G. , Braun Robert E.
Published: April 2021

In developing male germ cells, newly synthesized protamine mRNAs are stored for up to 7 days before translational activation. Translational repression of protamine 1 (Prm1) mRNA requires sequences present in its 3′ untranslated region (UTR) and substantial evidence suggests a role for the murine Y-box protein MSY4 in this process. To determine if MSY4 can mediate translational repression in vivo, we generated transgenic mice in which the temporal window of MSY4 expression was extended during spermatogenesis. Expression of MSY4 disrupted the normal completion of spermatogenesis and caused dominant sterility. Immunocytochemical analysis of several markers, including the protamines, indicated that MSY4 prevented normal activation of translation. mRNAs whose translation was inhibited contained at least one MSY4 RNA recognition site, suggesting sequence-dependent translational repression. Altered translational activation resulted in defective processing of protamine 2 and severe defects in sperm morphogenesis. These results suggest that MSY4 plays an active role in translational repression of several mRNAs in differentiating spermatids.
Two linkedhairy/Enhancer of split-related zebrafish genes,her1andher7, function together to refine alternating somite boundaries
Authors: Henry Clarissa A. , Urban Michael K. , Dill Kariena K. , Merlie John P. , Page Michelle F. , Kimmel Charles B. , Amacher Sharon L.
Published: April 2021

The formation of somites, reiterated structures that will give rise to vertebrae and muscles, is thought to be dependent upon a molecular oscillator that may involve the Notch pathway. hairy/Enhancer of split related [E(spl)]-related (her or hes) genes, potential targets of Notch signaling, have been implicated as an output of the molecular oscillator. We have isolated a zebrafish deficiency, b567, that deletes two linked her genes, her1 and her7. Homozygous b567 mutants have defective somites along the entire embryonic axis. Injection of a combination of her1 and her7 (her1+7) morpholino modified antisense oligonucleotides (MOs) phenocopies the b567 mutant somitic phenotype, indicating that her1 and her7 are necessary for normal somite formation and that defective somitogenesis in b567 mutant embryos is due to deletion of her1 and her7. Analysis at the cellular level indicates that somites in her1+7-deficient embryos are enlarged in the anterior-posterior dimension. Weak somite boundaries are often found within these enlarged somites which are delineated by stronger, but imperfect, boundaries. In addition, the anterior-posterior polarity of these enlarged somites is disorganized. Analysis of her1 MO-injected embryos and her7 MO-injected embryos indicates that although these genes have partially redundant functions in most of the trunk region, her1 is necessary for proper formation of the anteriormost somites and her7 is necessary for proper formation of somites posterior to somite 11. By following somite development over time, we demonstrate that her genes are necessary for the formation of alternating strong somite boundaries. Thus, even though two potential downstream components of Notch signaling are lacking in her1+7-deficient embryos, somite boundaries form, but do so with a one and a half to two segment periodicity.
Thetransformergene inCeratitis capitataprovides a genetic basis for selecting and remembering the sexual fate
Authors: Pane Attilio , Salvemini Marco , Bovi Pasquale Delli , Polito Catello , Saccone Giuseppe
Published: April 2021

The medfly Ceratitis capitata contains a gene (Cctra) with structural and functional homology to the Drosophila melanogaster sex-determining gene transformer (tra). Similar to tra in Drosophila, Cctra is regulated by alternative splicing such that only females can encode a full-length protein. In contrast to Drosophila, however, where tra is a subordinate target of Sex-lethal (Sxl), Cctra seems to initiate an autoregulatory mechanism in XX embryos that provides continuous tra female-specific function and act as a cellular memory maintaining the female pathway. Indeed, a transient interference with Cctra expression in XX embryos by RNAi treatment can cause complete sexual transformation of both germline and soma in adult flies, resulting in a fertile male XX phenotype. The male pathway seems to result when Cctra autoregulation is prevented and instead splice variants with truncated open reading frames are produced. We propose that this repression is achieved by the Y-linked male-determining factor (M).
Bimodal functions of Notch-mediated signaling are involved in neural crest formation during avian ectoderm development
Authors: Endo Yukinori , Osumi Noriko , Wakamatsu Yoshio
Published: April 2021

Neural crest is induced at the junction of epidermal ectoderm and neural plate by the mutual interaction of these tissues. In previous studies, BMP4 has been shown to pattern the ectodermal tissues, and BMP4 can induce neural crest cells from the neural plate. In this study, we show that epidermally expressed Delta1, which encodes a Notch ligand, is required for the activation and/or maintenance of Bmp4 expression in this tissue, and is thus indirectly required for neural crest induction by BMP4 at the epidermis-neural plate boundary. Notch activation in the epidermis additionally inhibits neural crest formation in this tissue, so that neural crest generation by BMP4 is restricted to the junction.
Using CRISPR to understand and manipulate gene regulation
Authors: Akinci Ersin , Hamilton Marisa C. , Khowpinitchai Benyapa , Sherwood Richard I.
Published: April 2021

Understanding how genes are expressed in the correct cell types and at the correct level is a key goal of developmental biology research. Gene regulation has traditionally been approached largely through observational methods, whereas perturbational approaches have lacked precision. CRISPR-Cas9 has begun to transform the study of gene regulation, allowing for precise manipulation of genomic sequences, epigenetic functionalization and gene expression. CRISPR-Cas9 technology has already led to the discovery of new paradigms in gene regulation and, as new CRISPR-based tools and methods continue to be developed, promises to transform our knowledge of the gene regulatory code and our ability to manipulate cell fate. Here, we discuss the current and future application of the emerging CRISPR toolbox toward predicting gene regulatory network behavior, improving stem cell disease modeling, dissecting the epigenetic code, reprogramming cell fate and treating diseases of gene dysregulation.
Development and maintenance of tendons and ligaments
Authors: Bobzin Lauren , Roberts Ryan R. , Chen Hung-Jhen , Crump J. Gage , Merrill Amy E.
Published: April 2021

Tendons and ligaments are fibrous connective tissues vital to the transmission of force and stabilization of the musculoskeletal system. Arising in precise regions of the embryo, tendons and ligaments share many properties and little is known about the molecular differences that differentiate them. Recent studies have revealed heterogeneity and plasticity within tendon and ligament cells, raising questions regarding the developmental mechanisms regulating tendon and ligament identity. Here, we discuss recent findings that contribute to our understanding of the mechanisms that establish and maintain tendon progenitors and their differentiated progeny in the head, trunk and limb. We also review the extent to which these findings are specific to certain anatomical regions and model organisms, and indicate which findings similarly apply to ligaments. Finally, we address current research regarding the cellular lineages that contribute to tendon and ligament repair, and to what extent their regulation is conserved within tendon and ligament development.
Direct repression of Nanog and Oct4 by OTX2 modulates the contribution of epiblast-derived cells to germline and somatic lineage
Authors: Di Giovannantonio Luca Giovanni , Acampora Dario , Omodei Daniela , Nigro Vincenzo , Barba Pasquale , Barbieri Elisa , Chambers Ian , Simeone Antonio
Published: April 2021

In mammals, the pre-gastrula proximal epiblast gives rise to primordial germ cells (PGCs) or somatic precursors in response to BMP4 and WNT signaling. Entry into the germline requires activation of a naïve-like pluripotency gene regulatory network (GRN). Recent work has shown that suppression of OTX2 expression in the epiblast by BMP4 allows cells to develop a PGC fate in a precise temporal window. However, the mechanisms by which OTX2 suppresses PGC fate are unknown. Here, we show that, in mice, OTX2 prevents epiblast cells from activating the pluripotency GRN by direct repression of Oct4 and Nanog. Loss of this control during PGC differentiation in vitro causes widespread activation of the pluripotency GRN and a deregulated response to LIF, BMP4 and WNT signaling. These abnormalities, in specific cell culture conditions, result in massive germline entry at the expense of somatic mesoderm differentiation. Increased generation of PGCs also occurs in mutant embryos. We propose that the OTX2-mediated repressive control of Oct4 and Nanog is the basis of the mechanism that determines epiblast contribution to germline and somatic lineage.
Immunology of nervegrowth factor (NGF). The effect of NGF-antiserumon sensory ganglia in vitro
Authors: Hoffman H.
Published: April 2021

The properties of the ‘Nerve Growth Factor’ (NGF) have been described extensively (Levi-Montalcini & Booker, 1960; Levi-Montalcini, 1965) and reviewed recently (Levi-Montalcini, 1966). This factor is a protein of molecular weight about 130000 in its aggregated form (Varon, Nomura & Shooter, 1967, 1968) but may be active in lower molecular weight forms (Cohen, 1959, 1960; Banks et al. 1968). It is widely distributed in the adult organism (Bueker, Schenkein & Bane, 1960) and exerts a controlling influence on the differentiation of sensory and sympathetic ganglia in developing chick embryos. In newborn mammals its administration influences sympathetic ganglion growth only. A possible role in the adult nervous system is suggested by Scott, Gutmann & Horsky (1966), who showed that injected NGF will increase protein synthesis in regenerating sensory neurons in vivo.
Accumulation of an organ-specific protein duringdevelopment of the embryonic chick brain
Authors: Friedman Harvey P. , Wenger Byron S.
Published: April 2021

In an earlier investigation by the present authors (Friedman & Wenger, 1965) the quantitative development of brain-specific antigens in chick embryos was studied using antisera against whole brain homogenates. The antisera employed were made brain specific by absorption with homogenates of various chicken tissues. Based on this study, the period between and 12 days of incubation, stages 28 and 38 of the Hamburger & Hamilton (1951) stage series, was considered to be critical for neural differentiation.
Sterility and partial sterility in the South African clawed toad following the pricking of the egg
Authors: Buehr Mia L. , Blackler Antonie W.
Published: April 2021

Bounoure (1934) first described the presence in the egg of the frog Rana temporaria of a special cytoplasmic differentiation, which he termed the ‘germinal cytoplasm’. He was able to trace the developmental history of this plasm as it moved from its original position just under the cortex of the vegetal pole of the fertilized egg, to its inclusion in a number of cells of the early gastrula endoderm, and also mapped the migration of these cells into the gonad rudiments. Bounoure believed that the germinal cytoplasm is the definitive germcell determinant, and that its presence in a cell is a prerequisite for the cell to undergo meiosis and differentiate into a gamete.
Behaviour of germ cells and sexual differentiation in late embryonic and early postnatal mouse chimeras
Authors: Mystkowska Ewa T. , Tarkowski Andrzej K.
Published: April 2021

The purpose of the present study was to trace the fate of primordial germ cells in mouse chimeras of XX/XY constitution. In this type of research one hopes to obtain knowledge of the role of intrinsic genetic factors and of environmental factors (the environment provided by the gonads) in initiating and directing the course of gametogenesis in mammals.
Granulosa cell-germ cell relationship in the developing rabbit ovary
Authors: Gondos Bernard
Published: April 2021

Granulosa cells play an important part in the nutrition of the oocyte during oogenesis (Raven, 1961). Anderson & Beams (1960) suggested that, in the primary follicle, nutritive material synthesized by the granulosa cells reaches the oocyte by diffusion across the zona pellucida. In the rabbit, follicle formation and elaboration of the zona pellucida begin at the end of the second week after birth (Gondos & Zamboni, 1967). Prior to this time germ cells and granulosa cells are clustered together within the ovarian cortex. Although participation of the granulosa cells in zona pellucida formation has been described in detail (Merker, 1961), the function of granulosa cells in the earlier stages of oogenesis is unclear. The following is an electron microscope study of the relationship between granulosa cells and germ cells in the prefollicular rabbit ovary.
The effect of exogenous RNA extract on chick embryo fibroblasts in vitro
Authors: Sann A. , Sharp D. , McKenzie J.
Published: April 2021

It is extremely difficult, if not impossible, to reconcile the conflicting claims of those who have treated different cells and tissues with exogenous RNA. Some authors (e.g. Niu, Cordova & Niu, 1961 ; Niu, Cordova & Radbill, 1962) maintain that RNA extracts alter the course of cell differentiation to conform in morphological terms to the source of the RNA; in the same vein, Amos, Askonas & Soeiro (1964) have shown that, under certain conditions, RNA from mouse and bacterial cells can stimulate chick embryo fibroblasts to synthesize protein related antigenically to the origin of the RNA. Shepley, Ambrose & Kirby (1965), however, obtained stimulation of growth with permanent morphological changes in baby hamster kidney fibroblasts by the addition of RNA from a variety of sources.

On the other hand, Holoubek, Fanshier & Crocker (1966) showed that nuclear RNA synthesis in Ehrlich ascites cells was inhibited for 6–8 h by the addition of homologous or rat liver RNA and our results are similar in that rat liver RNA extract has been shown to have an adverse effect on the growth and survival of chick embryo fibroblasts.
Cell populations in skeletal muscle after regeneration
Authors: Church J. C. T.
Published: April 2021

Much is known of the processes involved in the regeneration of skeletal muscle after injury. Yet in most accounts, the results are expressed in general or relative terms. Thus Adams, Denny-Brown & Pearson (1962) state that provided the architecture of the muscle survives, the reconstruction of ‘considerable lengths’ of muscle fibre is feasible. Wright (1963) makes a plea for the applica-tion of quantitation, with the choice of ‘some muscle that is sufficiently small for counting and measuring techniques to be reasonably applicable…’ The web of the fruit bat Eidolon helvum (Kerr) contains a number of small muscles which have proved very suitable for the detailed study, in light and electron micro-scopy, of muscle regeneration (Church & Noronha, 1965; Church, Noronha & Allbrook, 1966) (Fig. 1 A – D), and for the quantitation of recovering lesions (Church, 1968).
Etude ultrastructurale des stades précoces du développement du membre postérieur dePleurodeles waltliiMichah. (Amphibien, Urodèle)
Authors: Lauthier M.
Published: April 2021

An ultrastructural study of the early stages of development of the hind limb-bud has been carried out in Pleurodeles waltlii Michah. The most interesting results concern the structure of the epidermis and the evolution of the dermo-epidermal boundary in the limb-bud.

At every level of the limb-bud, the mesoderm draws near to the epidermis due to filopodia that penetrate the basal fibrous layer which becomes progressively disorganized; this can be considered as the establishment of interactions between epidermis and mesoderm. Some subepithelial cells with dense bodies participate in the disorganization of the basal fibrous layer.

There is no special epidermal feature at the limb-bud apex. However, the ultrastructural uniformity of the epidermis (which can be related to its histoenzymological uniformity) does not exclude a morphogenetic role of that epidermis.

The absence of any apical differentiation of the Pleurodeles hind limb-bud as well as the absence of a strictly localized disorganization of the basal fibrous layer and the closeness of the mesoderm and epidermis, are discussed. It is suggested that, if in Urodela the epidermis of the limb-bud plays a morphogenetic role, the whole epidermis is concerned and not only its apical part as in Amniotes. The differences observed at the level of the hind limb-bud between Urodela and the other Tetrapods could be related to the strikingly different chronological appearance of the toes in the two groups.