bluuebunny/crossref_metadata_2025 huggingface dataset:
Icariin protects against cage layer osteoporosis by intervening in steroid biosynthesis and glycerophospholipid metabolism
Authors: Yu Zhengwang , Huang Jie , Zhou Zhongxin
Published: April 2021

Cage layer osteoporosis (CLO) is a common bone metabolism disease in the breeding industry of China. However, effective prevention for CLO has not been developed. Icariin (ICA), the main bioactive component of the Chinese herb Epimedium, has been shown to have good therapeutic effects on bone-related diseases. In this study, the effects of ICA were further evaluated in a low-calcium diet-induced CLO, and a serum metabolomics assay was performed to understand the underlying mechanisms. A total of 144 31-wk-old Lohmann pink-shell laying hens were randomly allocated to 4 groups with 6 replicates of 6 hens per replicate. The 4 dietary treatment groups consisted of a basal diet (3.5% calcium), a low-calcium diet (2.0% calcium), and a low-calcium diet supplemented with 0.5 or 2.0 g/kg ICA. The results showed that ICA exerted good osteoprotective effects on low-calcium diet-induced CLO. ICA significantly increased femur bone mineral density, improved bone microstructure, decreased bone metabolic level, and upregulated mRNA expression of bone formation genes in femoral bone tissue. Serum untargeted metabolomics analysis showed that 8 metabolite levels were significantly changed after ICA treatment, including increased contents of 7-dehydrocholesterol, 7-oxocholesterol, desmosterol, PC (18:1(9Z)/18:1(9Z)), PS (18:0/18:1(9Z)), N,N-dimethylaniline and 2-hydroxy-butanoic acid and decreased N2,N2-dimethylguanosine. Metabolic pathway analysis based on the above 8 metabolites indicated that ICA mainly perturbed steroid biosynthesis and glycerophospholipid metabolism. These findings suggest that ICA can effectively prevent bone loss in low-calcium diet-induced CLO by mediating steroid biosynthesis and glycerophospholipid metabolism and provide new information for the regulation of bone metabolic diseases.
A numerically exact nonreflecting boundary condition applied to the acoustic Helmholtz equation
Authors: Mulder Wim A.
Published: April 2021

When modeling wave propagation, truncation of the computational domain to a manageable size requires nonreflecting boundaries. To construct such a boundary condition on one side of a rectangular domain for a finite-difference discretization of the acoustic wave equation in the frequency domain, the domain is extended on that one side to infinity. Constant extrapolation in the direction perpendicular to the boundary provides the material properties in the exterior. Domain decomposition can split the enlarged domain into the original one and its exterior. Because the boundary-value problem for the latter is translation-invariant, the boundary Green functions obey a quadratic matrix equation. Selection of the solvent that corresponds to the outgoing waves provides the input for the remaining problem in the interior. The result is a numerically exact nonreflecting boundary condition on one side of the domain. When two nonreflecting sides have a common corner, the translation invariance is lost. Treating each side independently in combination with a classic absorbing condition in the other direction restores the translation invariance and enables application of the method at the expense of numerical exactness. Solving the quadratic matrix equation with Newton’s method turns out to be more costly than solving the Helmholtz equation and may select unwanted incoming waves. A proposed direct method has a much lower cost and selects the correct branch. A test on a 2D acoustic marine seismic problem with a free surface at the top, a classic second-order Higdon condition at the bottom, and numerically exact boundaries at the two lateral sides demonstrates the capability of the method. Numerically exact boundaries on each side, each computed independently with a free-surface or Higdon condition, provide even better results.
3D spatial characterization of sand body for uranium reservoirs based on geostatistical resistivity inversion
Authors: Sun Zhangqing , Huang Xingguo , Li Hongliang , Lei Anguai , da Silva Nuno Vieira , Han Fuxing , Cao Minqiang , Da Wei
Published: April 2021

The concern over climate change and a transition away from fossil fuels has reinvigorated interest in using nuclear energy in producing electricity. Uranium is the principal fuel used in nuclear power plants, and mineral deposits containing this element are of strategic importance. The successful development of sandstone uranium deposits benefits from 3D geophysical characterization of sand bodies in uranium reservoirs. In view of this, we have evaluated a method based on 3D geostatistical resistivity inversion. First, we analyze the application of that method to the problem at hand and introduce a workflow for analyzing the data. Second, through petrophysical sensitivity analysis, we identify the logging parameters that can characterize sandstone in this context and geostatistical inversion to estimate those parameters. We then use 3D geostatistical resistivity inversion to map a sandstone uranium reservoir and find it to provide accurate results. Finally, the 3D data of inversion are applied to 3D spatial characterization of a sand body in the Sifangtai uranium reservoir inverting a field data set in the western of Songliao Basin in China. We believe this geostatistical inversion method to be useful in determining the location of drilling wells for exploration and development of sandstone uranium deposits.
Assessing recovery in treatment as usual provided by community child and adolescent mental health services
Authors: Gibbons Naomi , Harrison Emma , Stallard Paul
Published: April 2021

Background

Despite the importance of routinely assessing the outcomes of everyday practice, few studies have reported outcome metrics for child and adolescent mental health services (CAMHS).

Aims

Our aim is to investigate reliable change and recovery rates for treatment as usual, provided by one community CAMHS over two time periods.

Method

We prospectively audited accepted consecutive referrals from November 2017 to January 2018, and April to September 2019. Cases with paired outcomes were identified, and reliable change and recovery rates were calculated.

Results

Baseline outcome data were obtained for 672 (78.2%) and 744 (77.5%) young people in 2018 and 2019, respectively. Of eligible participants, 174 (59.2%) and 155 (45.7%) completed at least one follow-up outcome measure in 2018 and 2019, respectively. Pre- and post-test scores on the Revised Child Anxiety and Depression Scale (RCADS) and Strengths and Difficulties Questionnaire (SDQ) showed a reduction in symptoms. Total RCADS scores showed 21–25% of participants reliably improved, with 44–49% showing reliable improvement on one or more subscale. On the SDQ, 11 (15.5%) and 19 (25.3%) participants reported reliable improvement on at least one subscale in 2018 and 2019, respectively. Reliable recovery rates ranged from 48 to 51% for youth-completed and 40 to 42% for parent-completed RCADS.

Conclusions

Half of young people receiving treatment as usual from CAMHS reliably improved on at least one routine outcome measure subscale, improvement rates comparable with adult psychological therapies services. Our findings indicate that reliable change and recovery on subscale rather than total scores may be a better indication of outcomes.
Ten-Year Outcome of Neoadjuvant Chemoradiotherapy Plus Surgery for Esophageal Cancer: The Randomized Controlled CROSS Trial
Authors: Eyck Ben M. , van Lanschot J. Jan B. , Hulshof Maarten C. C. M. , van der Wilk Berend J. , Shapiro Joel , van Hagen Pieter , van Berge Henegouwen Mark I. , Wijnhoven Bas P. L. , van Laarhoven Hanneke W. M. , Nieuwenhuijzen Grard A. P. , Hospers Geke A. P. , Bonenkamp Johannes J. , Cuesta Miguel A. , Blaisse Reinoud J. B. , Busch Olivier R. , Creemers Geert-Jan M. , Punt Cornelis J. A. , Plukker John Th. M. , Verheul Henk M. W. , Spillenaar Bilgen Ernst J. , van der Sangen Maurice J. C. , Rozema Tom , ten Kate Fiebo J. W. , Beukema Jannet C. , Piet Anna H. M. , van Rij Caroline M. , Reinders Janny G. , Tilanus Hugo W. , Steyerberg Ewout W. , van der Gaast Ate ,   for the CROSS Study Group
Published: April 2021

PURPOSE

Preoperative chemoradiotherapy according to the chemoradiotherapy for esophageal cancer followed by surgery study (CROSS) has become a standard of care for patients with locally advanced resectable esophageal or junctional cancer. We aimed to assess long-term outcome of this regimen.

METHODS

From 2004 through 2008, we randomly assigned 366 patients to either five weekly cycles of carboplatin and paclitaxel with concurrent radiotherapy (41.4 Gy in 23 fractions, 5 days per week) followed by surgery, or surgery alone. Follow-up data were collected through 2018. Cox regression analyses were performed to compare overall survival, cause-specific survival, and risks of locoregional and distant relapse. The effect of neoadjuvant chemoradiotherapy beyond 5 years of follow-up was tested with time-dependent Cox regression and landmark analyses.

RESULTS

The median follow-up was 147 months (interquartile range, 134-157). Patients receiving neoadjuvant chemoradiotherapy had better overall survival (hazard ratio [HR], 0.70; 95% CI, 0.55 to 0.89). The effect of neoadjuvant chemoradiotherapy on overall survival was not time-dependent ( P value for interaction, P = .73), and landmark analyses suggested a stable effect on overall survival up to 10 years of follow-up. The absolute 10-year overall survival benefit was 13% (38% v 25%). Neoadjuvant chemoradiotherapy reduced risk of death from esophageal cancer (HR, 0.60; 95% CI, 0.46 to 0.80). Death from other causes was similar between study arms (HR, 1.17; 95% CI, 0.68 to 1.99). Although a clear effect on isolated locoregional (HR, 0.40; 95% CI, 0.21 to 0.72) and synchronous locoregional plus distant relapse (HR, 0.43; 95% CI, 0.26 to 0.72) persisted, isolated distant relapse was comparable (HR, 0.76; 95% CI, 0.52 to 1.13).

CONCLUSION

The overall survival benefit of patients with locally advanced resectable esophageal or junctional cancer who receive preoperative chemoradiotherapy according to CROSS persists for at least 10 years.
Atezolizumab, Bevacizumab, and Chemotherapy for Newly Diagnosed Stage III or IV Ovarian Cancer: Placebo-Controlled Randomized Phase III Trial (IMagyn050/GOG 3015/ENGOT-OV39)
Authors: Moore Kathleen N. , Bookman Michael , Sehouli Jalid , Miller Austin , Anderson Charles , Scambia Giovanni , Myers Tashanna , Taskiran Cagatay , Robison Katina , Mäenpää Johanna , Willmott Lyndsay , Colombo Nicoletta , Thomes-Pepin Jessica , Liontos Michalis , Gold Michael A. , Garcia Yolanda , Sharma Sudarshan K. , Darus Christopher J. , Aghajanian Carol , Okamoto Aikou , Wu Xiaohua , Safin Rustem , Wu Fan , Molinero Luciana , Maiya Vidya , Khor Victor K. , Lin Yvonne G. , Pignata Sandro
Published: April 2021

PURPOSE

To evaluate the addition of the humanized monoclonal antiprogrammed death ligand-1 (PD-L1) antibody, atezolizumab, to platinum-based chemotherapy and bevacizumab in newly diagnosed stage III or IV ovarian cancer (OC).

METHODS

This multicenter placebo-controlled double-blind randomized phase III trial (ClinicalTrials.gov identifier: NCT03038100 ) enrolled patients with newly diagnosed untreated International Federation of Gynecology and Obstetrics (FIGO) stage III or IV OC who either had undergone primary cytoreductive surgery with macroscopic residual disease or were planned to receive neoadjuvant chemotherapy and interval surgery. Patients were stratified by FIGO stage, Eastern Cooperative Oncology Group performance status, tumor immune cell PD-L1 staining, and treatment strategy and randomly assigned 1:1 to receive 3-weekly cycles of atezolizumab 1,200 mg or placebo (day 1, cycles 1-22), with paclitaxel plus carboplatin (day 1, cycles 1-6) plus bevacizumab 15 mg/kg (day 1, cycles 2-22), omitting perioperative bevacizumab in neoadjuvant patients. The co-primary end points were investigator-assessed progression-free survival and overall survival in the intention-to-treat and PD-L1–positive populations.

RESULTS

Between March 8, 2017, and March 26, 2019, 1,301 patients were enrolled. The median progression-free survival was 19.5 versus 18.4 months with atezolizumab versus placebo, respectively (hazard ratio, 0.92; 95% CI, 0.79 to 1.07; stratified log-rank P = .28), in the intention-to-treat population and 20.8 versus 18.5 months, respectively (hazard ratio, 0.80; 95% CI, 0.65 to 0.99; P = .038), in the PD-L1–positive population. The interim (immature) overall survival results showed no significant benefit from atezolizumab. The most common grade 3 or 4 adverse events were neutropenia (21% with atezolizumab v 21% with placebo), hypertension (18% v 20%, respectively), and anemia (12% v 12%).

CONCLUSION

Current evidence does not support the use of immune checkpoint inhibitors in newly diagnosed OC. Insight from this trial should inform further evaluation of immunotherapy in OC.
Impaired Function and Altered Morphology in the Skeletal Muscles of Adult Men and Women With Type 1 Diabetes
Authors: Dial Athan G , Monaco Cynthia M F , Grafham Grace K , Patel Tirth P , Tarnopolsky Mark A , Hawke Thomas J
Published: April 2021

Context

Previous investigations on skeletal muscle health in type 1 diabetes (T1D) have generally focused on later stages of disease progression where comorbidities are present and are posited as a primary mechanism of muscle dysfunction.

Objective

To investigate skeletal muscle function and morphology across the adult lifespan in those with and without T1D.

Design

Participants underwent maximal contraction (MVC) testing, resting muscle biopsy, and venous blood sampling.

Setting

Procedures in this study were undertaken at the McMaster University Medical Centre.

Participants

Sixty-five healthy adult (18-78 years old) men/males and women/females (T1D = 34; control = 31) matched for age/biological sex/body mass index; self-reported physical activity levels were included.

Main Outcome Measures

Our primary measure in this study was MVC, with supporting histological/immunofluorescent measures.

Results

After 35 years of age (“older adults”), MVC declined quicker in T1D subjects compared to controls. Loss of strength in T1D was accompanied by morphological changes associated with accelerated aging. Type 1 myofiber grouping was higher in T1D, and the groups were larger and more numerous than in controls. Older T1D females exhibited more myofibers expressing multiple myosin heavy chain isoforms (hybrid fibers) than controls, another feature of accelerated aging. Conversely, T1D males exhibited a shift toward type 2 fibers, with less evidence of myofiber grouping or hybrid fibers.

Conclusions

These data suggest impairments to skeletal muscle function and morphology exist in T1D. The decline in strength with T1D is accelerated after 35 years of age and may be responsible for the earlier onset of frailty, which characterizes those with diabetes.
Leptin Decreases Energy Expenditure Despite Increased Thyroid Hormone in Patients With Lipodystrophy
Authors: Grover Andrew , Quaye Emmanuel , Brychta Robert J , Christensen John , Startzell Megan S , Meehan Cristina Adelia , Valencia Areli , Marshall Brandon , Chen Kong Y , Brown Rebecca J
Published: April 2021

Context

Leptin is an adipokine that signals energy sufficiency. In rodents, leptin deficiency decreases energy expenditure (EE), which is corrected following leptin replacement. In humans, data are mixed regarding leptin-mediated effects on EE.

Objective

To determine the effects of metreleptin on EE in patients with lipodystrophy.

Design, setting, and patients

Nonrandomized crossover study of 25 patients with lipodystrophy (National Institutes of Health, 2013-2018).

Intervention

The initiation cohort consisted of 17 patients without prior exposure to metreleptin, studied before and after 14 days of metreleptin. The withdrawal cohort consisted of 8 previously metreleptin-treated patients, studied before and after 14 days of metreleptin withdrawal.

Main outcomes

24-h total energy expenditure (TEE), resting energy expenditure (REE), autonomic nervous system activity [heart rate variability (HrV)], plasma-free triiodothyronine (T3), free thyroxine (T4), epinephrine, norepinephrine, and dopamine.

Results

In the initiation cohort, TEE and REE decreased by 5.0% (121 ± 152 kcal/day; P = 0.006) and 5.9% (120 ± 175 kcal/day; P = 0.02). Free T3 increased by 19.4% (40 ± 49 pg/dL; P = 0.01). No changes in catecholamines or HrV were observed. In the withdrawal cohort, free T3 decreased by 8.0% (P = 0.04), free T4 decreased by 11.9% (P = 0.002), and norepinephrine decreased by 34.2% (P = 0.03), but no changes in EE, epinephrine, dopamine, or HrV were observed.

Conclusions

Metreleptin initiation decreased EE in patients with lipodystrophy, but no changes were observed after metreleptin withdrawal. Thyroid hormone was higher on metreleptin in both initiation and withdrawal cohorts. Decreased EE after metreleptin in lipodystrophy may result from reductions in energy-requiring metabolic processes that counteract increases in EE via adipose tissue-specific neuroendocrine and adrenergic signaling.
Histolysis, Histogenesis, and Differentiation during Insect Metamorphosis in Relation to Metabolic Changes
Authors: Agrell Ivar
Published: April 2021

The most obvious change in metabolism during the more advanced type of insect metamorphosis is the change in the integral metabolic activity. After pupation there is first a marked decrease and later an increase of, for instance, the oxygen consumption. The respiratory metabolic curve is U-shaped. The cause of this change is a corresponding variation in the activity of oxidative enzyme systems. If one compares the variation of the spontaneous Mb-reduction and of the oxygen consumption in the fly Calliphora, one finds that the two curves have almost the same course (Agrell, 1947b). This shows an important co-operation of the dehydrogenase systems. The cytochrome system also shows a similar U-shaped variation during the period of metamorphosis, according to Wolsky (1938), Williams (1948) and Sacktor (1950). One limiting factor is the protein part of the enzymes, which is first broken down and later rebuilt (Agrell, 1946). Another limiting factor is the prosthetic heme group in the cytochromes (Williams, 1951). According to Sandborn & Williams (1950) there is also a change over from a cytochrome X, possibly identical with Keilin’s cytochrome E, to cytochrome C at pupation.
An RNA-binding protein fromXenopusoocytes is associated with specific message sequences
Authors: Crawford Dana R. , Richter Joel D.
Published: April 2021

Monoclonal antibodies directed against an RNA-binding protein from Xenopus oocytes were used to immunoselect messenger ribonucleoprotein (mRNP) particles. RNA was extracted from both the immunoselected and nonselected fractions and was used to direct the synthesis of oligo (dT)-primed 32P-cDNA. These two cDNA preparations were then used to probe Xenopus stage-1 oocyte cDNA libraries to identify sequences that had been specifically coimmunoselected by the antibodies. Three cDNA clones were shown to be derived specifically from the antibody-selected mRNPs. During very early oogenesis (stage 1–2), the RNA-binding protein and the three coselected mRNAs sediment in the nontranslating mRNP region of a sucrose gradient. By oocyte stage 6, the binding protein concentration decreases by as much as 22-fold relative to polyadenylated RNA. At this stage of development, the three mRNAs are found predominantly in the polysome region of a sucrose gradient. These data demonstrate that Xenopus oocytes contain an RNA-binding protein which binds specific message sequences and may regulate their expression.
Exogenous basement-membrane-like matrix stimulates adrenergic development in avian neural crest cultures
Authors: Maxwell Gerald D. , Forbes M. Elizabeth
Published: April 2021

The development of quail trunk neural crest cultures was dramatically altered when the cultures were overlaid with a gel of reconstituted basement membrane (RBM) components derived from the Engel-breth-Holm-Swarm sarcoma. In the presence of the RBM gel overlay, the number of catecholaminepositive (CA+) cells that developed was increased 50fold, while the final number of melanocytes and total cells was only half that seen in the control cultures. The presence of the RBM gel overlay did not alter the time of onset of differentiation of the CA+ cells or melanocytes. The stimulation of CA+ cell number was not observed with type IV collagen substrates, laminin substrates or type I collagen gel overlays with or without added laminin. The stimulation of CA+ cell development was dependent on initial plating density. The number of CAT cells that developed in the presence of the RBM gel was proportional to the initial plating density at 80–320 cells mm−2, whereas no CA+ cells were observed below 20 cells mm−2 and only a few CA+ cells were detected at 40 cells mm−2. There was, however, extensive cell division and differentiation of melanocytes and unpigmented cells at the lower initial plating densities. When the RBM gel was used as a substrate, rather than as an overlay, a striking rearrangement of cells into interconnected strands was observed. After several days in culture, melanocytes, CA+ cells and unpigmented cells were present in these strands. These results indicate that molecules associated with a reconstituted basementmembrane-like matrix are a potent stimulatory influence on adrenergic development and also act to inhibit the production of other cell types in neural crest cultures.
Genetic analysis of the human Y chromosome by chromosome-mediated gene transfer
Authors: Pritchard Catrin A. , Goodfellow Peter N.
Published: April 2021

Chromosome-mediated gene transfer (CMGT) can be used to segregate fragments of human chromosomes in human-rodent hybrid cells. As with all somatic cell genetics methods, a selection technique is needed to isolate the hybrid cell lines produced by CMGT. Expression of the MIC2 gene product on the cell surface (the 12E7 antigen) provides an endogenous selectable marker for the human Y chromosome. Using chromosome transfer followed by separation of 12E7 antigen-positive cells on the fluorescence-activated cell sorter, a series of cell lines containing segregated fragments of the Y chromosome have been derived. The possibility of using these fragments to derive fine structural mapping data for the Y chromosome is considered in this review.
Gene Activity in Early Development
Authors: Davidson Eric H. , Scott Matthew P.
Published: April 2021

In 1925, Edmund Wilson published the now classic third edition of his book The Cell in Development and Heredity, in which he laid out most of the important questions about developmental biology that we are still attempting to answer. In 1986, Eric Davidson published the third edition of his book Gene Activity in Early Development, in which the progress toward answering Wilson’s questions is described. Wilson (1896) is quoted: “If chromatin be the idioplasm … in which inheres the sum total of hereditary forces, and if it be equally distributed at every cell division, how can its mode of action so vary in different cells as to cause diversity of structure, i.e. differentiation?” How indeed. It would be fascinating to hear Wilson’s responses after informing him of enhancers and RNA splicing. Davidson is clearly an admirer of Wilson, and like Wilson has a broad perspective on the field which brings to the new edition the strengths of a profound knowledge of classical developmental biology together with an appreciation of the power of the new molecular methods.
Development of the two-part pattern during regeneration of the head in hydra
Authors: Bode P. M. , Awad T. A. , Koizumi O. , Nakashima Y. , Grimmelikhuijzen C. J. P. , Bode H. R.
Published: April 2021

The head of a hydra is composed of two parts, a domed hypostome with a mouth at the top and a ring of tentacles below. When animals are decapitated a new head regenerates. During the process of regeneration the apical tip passes through a transient stage in which it exhibits tentacle-like characteristics before becoming a hypostome. This was determined from markers which appeared before morphogenesis took place. The first was a monoclonal antibody, TS-19, that specifically binds to the ectodermal epithelial cells of the tentacles. The second was an antiserum against the peptide Arg-Phe-amide (RFamide), which in the head of hydra is specific to the sensory cells of the hypostomal apex and the ganglion cells of the lower hypostome and tentacles. The TS-19 expression and the ganglion cells with RFamide-like immunoreactivity (RLI) arose first at the apex and spread radially. Once the tentacles began evaginating in a ring, both the TS-19 antigen and RLI+ ganglion cells gradually disappeared from the presumptive hypostome area and RLI+ sensory cells appeared at the apex. By tracking tissue movements during morphogenesis it became clear that the apical cap, in which these changes took place, did not undergo tissue turnover. The implications of this tentacle-like stage for patterning the two-part head are discussed.
Head and thoracic transformations caused by ectopic expression ofAntennapediaduringDrosophiladevelopment
Authors: Gibson Greg , Gehring Walter J.
Published: April 2021

Segmental identity in Drosophila is controlled by the activities of the homeotic genes. One such gene is Antennapedia, which is required for the proper development of the thoracic segments. Alteration of Antennapedia expression either in mutants, or artificially using an inducible promoter, can lead to alterations of segmental identity. In this report, we present the consequences of ectopic expression of the Antennapedia gene under the control of a heat-shock promoter, at distinct stages throughout Drosophila development. In young embryos, up to the stage of germband retraction, the ubiquitous expression of the Antennapedia protein causes a range of effects throughout the embryo, including failure of head involution, induction of extra denticles on the dorsal surface of the head and disruption of the prothoracic denticle belts. In older embryos, it results in larval lethality. Heat shocks during larval development can lead to defects in leg formation, but no alterations in leg identity have been observed. However, clear transformations of head towards second (meso-) thoracic segment can be induced in early third instar larvae. There is a distal-to-proximal temporal response to ectopic Antennapedia expression in the antennal disc, as evidenced by successive transformations of the arista, third antennal segment, second antennal segment and occiput towards their corresponding leg and dorsal thoracic structures. Overproduction of Antennapedia protein during the pupal stage is generally lethal. Comparison of the homeotic transformations in, and Western analysis of, different lines suggests that a relatively large amount of Antennapedia protein is required to cause antenna-to-leg transformations, and further argues that, in general, developmental programmes in the insect are well buffered against the effects of ectopic homeotic gene expression. Immunodetection of Scr and Antp protein also allows us to interpret the results in light of the hypothesis that the various selector genes compete with one another to control not only their own expression, but also that of downstream genes. The role of Antennapedia in imaginai disc determination is also discussed.
Positional signals: evidence for a possible role in muscle fibre-type patterning of the embryonic avian limb
Authors: Butler J. , Cosmos E. , Cauwenbergs P.
Published: April 2021

Current evidence favours the hypothesis that avian muscle fibre-type differentiation is intrinsically programmed during early embryogenesis and proceeds independent of neuronal influences (for review, Miller & Stockdale, 1987; Sanes, 1987). Previous interspecific (chick/quail) and intraspecific (chick/chick) chimaeric studies, involving the heterotopic transplantation of unsegmented somitic mesoderm, indicate that the ability of premyogenic cells to form specific limb muscles is determined by positional cues operative in the host embryo. To determine if similar influences are associated with embryonic fibre-type differentiation, the limb musculature of intraspecific (chick/chick) chimaeras was assessed using differential myosin-ATPase activity. The limb musculature analysed histochemically was derived from donor unsegmented thoracic somitic mesoderm transplanted to replace extirpated brachial somites of a host embryo at 48 –52 h in ovo. Our results demonstrated that (1) the donor tissue formed, on schedule, an appropriate brachial musculature and (2) the experimental muscles duplicated the fibre-type patterning characteristic of control muscles. Thus, our data suggest that an extramyogenic, non-neural factor(s) operative in the host limb-forming region is associated with both muscle pattern formation and muscle fibre-type pattern formation. Whether or not the same putative factor(s) influences both processes remains to be determined.
Diploid mouse embryos constructed at the late 2-cell stage from haploid parthenotes and androgenotes can develop to term
Authors: Barra J. , Renard J.-P.
Published: April 2021

Male and female gamete nuclei are required to ensure the full-term development of the mouse embryo. Differential expression of the two genomes has been proposed as the basis for this requirement. In order to investigate whether some interactions between the paternal and the maternal genomes are essential before or at the time of the activation of the embryonic genome, we have constructed diploid embryos from haploid parthenotes and androgenotes at the late 2-cell stage. These embryos developed to term into normal offsprings. This shows that the male and the female genomes can be activated separately and are still able to ensure complete development when put together in cytoplasm synchronized with the nuclei. These experiments also show that the egg cytoplasm does not need any male contribution before the late 2-cell stage.
Stability of RNA in developing Xenopus embryos and identification of a destabilizing sequence in TFIIIA messenger RNA
Authors: Harland Richard , Misher Lynda
Published: April 2021

Synthetic capped RNA transcripts injected into fertilized eggs of Xenopus laevis have a half-life of 3 –4 h. Addition of a long (∼200 nucleotide) poly(A) tail increases the half-life to 6 –8 h which approaches the half-life of natural polyadenylated globin RNA injected into embryos. Since exonucleolytic action alone could account for the degradation of RNA, we tested whether circular RNA is stable after injection and find that circles are exceptionally stable (half-life greater than 40 h). After the midblastula transition, polyadenylated chloramphenicol transferase (CAT) mRNAs transcribed from injected plasmids have a half-life of 2 ·5 h. Insertion of a 1000 nucleotide 3′ untranslated region from the Xhox-36 gene into the transcripts does not affect the half-life. In contrast to the finding that internal sequences do not affect stability, we find that sequences from the TFIIIA message reduce the half-life of CAT mRNA from 2 ·5 h to less than 30 min. We conclude that most RNAs are degraded exonucleolytically from the 3′ end, but specialized internal sequences can greatly destabilize the RNA, possibly by acting as a site for an endonuclease.
Segmental pattern of development of the hindbrain and spinal cord of the zebrafish embryo
Authors: Hanneman Eric , Trevarrow Bill , Metcalfe Walter K. , Kimmel Charles B. , Westerfield Monte
Published: April 2021

In the ventral hindbrain and spinal cord of zebrafish embryos, the first neurones that can be identified appear as single cells or small clusters of cells, distributed periodically at intervals equal to the length of a somite. In the hindbrain, a series of neuromeres of corresponding length is present, and the earliest neurones are located in the centres of each neuromere. Young neurones within both the hindbrain and spinal cord were identified in live embryos using Nomarski optics, and histochemically by labelling for acetylcholinesterase activity and expression of an antigen recognized by the monoclonal antibody zn-1. Among them are individually identified hindbrain reticulospinal neurones and spinal motoneurones. These obervations suggest that early development in these regions of the CNS reflects a common segmental pattern. Subsequently, as more neurones differentiate, the initially similar patterning of the cells in these two regions diverges. A continuous longitudinal column of developing neurones appears in the spinal cord, whereas an alternating series of large and small clusters of neurones is present in the hindbrain.
The contribution made by a single somite to the vertebral column: experimental evidence in support of resegmentation using the chick–quail chimaera model
Authors: Bagnall K. M. , Higgins S. J. , Sanders E. J.
Published: April 2021

The somitic involvement in the formation of the vertebral column was examined using the chick-quail chimaera model. Single cervical somites from quail donor embryos were transplanted into similarly staged chick host embryos. Following further incubation, serial sections of variously staged embryos were stained with the Feulgen reaction to distinguish the two cell populations.

Quail cells were generally located within a delimited region in one half of each of the two adjacent vertebrae, as well as in the intervening disc. The horizontal plane of division through each vertebra passed approximately through the centre of the body and divided the neural arch into rostral and caudal halves through the rostral border of the caudal notch. These results give support to the controversial theory of resegmentation, in which it was suggested that there is an apparent realignment of segmentation between the somite stage and the subsequent vertebral stage of development.
A Dictyostelium prespore-specific gene is transcriptionally repressed by DIF in vitro
Authors: Early A. E. , Williams J. G.
Published: April 2021

One important role of DIF, the stalk cell-specific inducer of Dictyostelium, may be to divert cells from the spore cell pathway of differentiation. The D19 gene encodes an mRNA which is highly enriched in prespore over prestalk cells in the migratory slug. We show, using a mutant defective in DIF accumulation, that the concentration of D19, and several other prespore mRNA sequences, decreases in the presence of exogenous DIF. There is evidence that both transcriptional and post-transcriptional controls operate to regulate expression of these genes. We have performed in vitro nuclear transcription and mRNA halflife analyses, and find that DIF acts at the transcriptional level to repress the accumulation of the D19 mRNA.
Origin of the dorsal surface of the neural tube by progressive delamination of epidermal ectoderm and neuroepithelium: implications for neurulation and neural tube defects
Authors: Martins-Green Manuela
Published: April 2021

Knowledge of the morphogenetic events involved in the development of the dorsal portion of the neural tube is important for understanding neural tube closure, neural crest cell formation and emigration, and the origin of neural tube defects. Here, I characterize the progressive development of the tips of the neural folds during fold elevation in the trunk of mouse and chick embryos and the events leading to formation of the dorsal portion of the neural tube as the epidermal ectoderm (EE) and neuroepithelium (NE) separate from each other. The nature and timing of appearance of collagen IV, laminin and fibronectin were analysed by immunofluorescent and immunogold labelling, and ruthenium red and tannic acid were used to enhance staining for proteoglycans and glycosaminoglycans. As the neural folds elevate, the NE and EE delaminate progressively beginning at the basal surface of the lateral extremes of the neural plate. Nevertheless, the two epithelia remain connected across the zone of delamination by their previously existing basal laminae. In each fold, proteoglycan granules appear at the interface between the NE and EE before delamination begins, and then an (inter-epithelial) space begins to open and propagate dorsally. Other extracellular matrix (ECM) molecules appear within the space a short distance behind its tip and basal lamina deposition begins shortly thereafter. As fusion occurs, the interepithelial spaces of the two folds coalesce and the final separation of the EE from the NE is accomplished. These observations suggest that the previously recognized delay in deposition of ECM and basal lamina on the dorsal portion of the neural tube and on the overlying EE is a direct consequence of the delamination of the two epithelia and the establishment of two new basal surfaces. The observation that the surface of the dorsal third of the neural tube forms by delamination rather than by juxtaposition of previously existing basal surfaces of the two epithelia is discussed in terms of possible implications for models of neurulation and the origin of neural tube defects.
Pepsinogen gene transcription induced in heterologous epithelial—mesenchymal recombinations of chicken endoderms and glandular stomach mesenchyme
Authors: Hayashi Kensuke , Yasugi Sadao , Mizuno Takeo
Published: April 2021

Proventricular (glandular stomach) mesenchyme of chicken embryos can induce endoderms of some parts of embryonic digestive tract to produce embryonic chicken pepsinogen (ECPg), a marker protein for the differentiation of embryonic proventricular epithelium. In the present study, we investigated the production of ECPg mRNA in the course of epithelial-mesenchymal interactions between endoderms of digestive tract and proventricular mesenchyme. ECPg mRNA was detected by Northern hybridization with ECPg cDNA as a probe. In normal development of the proventriculus, ECPg mRNA was first detected at day 7 of incubation, and it ceased to be produced by day 21. Embryonic esophagus, gizzard and small intestine did not contain ECPg mRNA. When 6-day esophagus, gizzard or proventricular endoderm was associated and cultured with 6-day proventricular mesenchyme, the recombinates formed proventricular-gland-like complex glands and produced ECPg mRNA in almost equal quantity. However, 6-day small intestinal or 3·5-day allantoic endoderm did not produce pepsinogen mRNA under the same conditions, though the recombinates formed complex glands. These results indicate that the proventricular mesenchyme can induce de novo transcription of ECPg gene in esophagus, proventricular and gizzard endoderms, and that ECPg gene in small intestinal and allantoic endoderms fails to react to the inducing signal.
The expression of epidermal antigens inXenopus laevis
Authors: Itoh Keiji , Yamashita Akiko , Kubota Hiroshi Y.
Published: April 2021

Five kinds of monoclonal antibodies that are specific for the epidermis of Xenopus embryos were produced. Epidermis-specific antibodies were used to investigate the spatial and temporal expressions of epidermal antigens during embryonic and larval development. The cells that were recognized by the antibodies at the larval stage are as follows: all of the outer epidermal cells and cement gland cells were recognized by the antibody termed XEPI-1, all of the outer and inner epidermal cells, except the cement gland cells, were recognized by XEPI-2 antibody, the large mucus granules and the apical side of the outer epidermal cells, except for the ciliated epidermal cells, were recognized by XEPI-3 antibody, the large mucus granules and basement membrane were recognized by XEPI-4 antibody, and the small mucus granules contained in the outer epidermal cells as well as extracellular matrices were recognized by the antibody termed XEPI-5. All of the epidermal antigens, except XEPI-4, were first detected in the epidermal region of the late gastrula or early neurula. The XEPI-4 antigen was first detected in stage-26 tail-bud embryos. None of these antigens were expressed by the neural tissues at any time during embryonic development. Only the XEPI-2 antigen continued to be expressed after metamorphosis, while the expression of the other antigens disappeared during or before metamorphosis. The specificity of the antibodies allowed us to classify the epidermal cells into four types in early epidermal development. The four types of epidermal cells are (1) the outer epidermal cells that contain small mucus granules, (2) the ciliated epidermal cells, (3) the outer epidermal cells that contain large mucus granules and (4) the inner sensorial cells.
Embryonic expression pattern of TGF beta type-1 RNA suggests both paracrine and autocrine mechanisms of action
Authors: Lehnert Sigrid A. , Akhurst Rosemary J.
Published: April 2021

The tissue distribution of TGF beta form 1 RNA within mouse embryos of 10·5 to 15·5 days gestational age was investigated using in situ hybridization. As predicted from the prevalence of TGF beta-1 protein in adult bone and platelets, the RNA is highly abundant in fetal bone and in fetal liver megakaryocytes. Our data also reveal previously undocumented sites of synthesis for TGF beta-1, namely epithelia overlying those mesenchymal tissues that are known to contain TGF beta protein as detected by immunohistochemical methods (Heine et al. 1987) and in the mesenchymal tissues of certain internal organs. From a combined knowledge of the distributions of the TGF beta polypeptide (Heine et al. 1987) and its mRNA, and a knowledge of the reported biological activities of TGF beta-1, we invoke both paracrine and autocrine mechanisms of action for this growth factor.
Isolation of differentially expressed human cDNA clones: similarities between mouse and human embryonal carcinoma cell differentiation
Authors: Wiles Michael V.
Published: April 2021

The study of early human development is of great importance but has been limited by the lack of suitable reagents. Recently, however, the human embryonal carcinoma (EC) cell line NT2D1 has been isolated. This cell line will differentiate upon exposure to retinoic acid (RA). A cDNA library was constructed from poly(A)+ RNA derived from NT2D1 cells treated with 10−5M-RA for 7 days (ANT2D1 cells). By differential cDNA screening, it was found that 1-12% of ANT2D1 cDNA recombinants screened detected an increase in signal with 32P-cDNAs derived from ANT2D1 as compared with NT2D1.

To compare RA-induced differentiation of mouse and human EC cells, the ANT2D1 cDNA library was rescreened with 32P-cDNAs derived from the mouse EC cell line F9 and the result compared with 32P-cDNA derived from F9 differentiated to parietal-endoderm (F9PE)-like cells and visceral-endoderm (F9VE)-like cells. Approximately 1·2% of the ANT2D1 cDNA recombinants detected a differential increase in signal following differentiation of mouse EC cells to F9VE and/or F9PE. Of these homologous regulated sequences, 0·3 % were common to both mouse and human EC cell RA-induced differentiation. Five different cDNA clones were isolated that detect a marked increase (5- to 75-fold) in mRNA abundance following RA-induced differentiation of NT2D1. Of these five clones, three detect homologous mRNAs which also increase in abundance following differentiation of the mouse EC cell line F9 to PE- and/or VE-like cells; the other two clones do not detect sequences in the mouse mRNAs tested. One clone shows homology to SPARC, a gene known to be regulated during mouse embryonic development. While another clone, SO5A, has a limited range of expression, being detected in F9VE and in a human parietal-endodermlike cell, but not in F9PE and a human visceral-endoderm-like cell.

This work shows that there are both similarities and differences in mouse and human EC cell differentiation, and these cDNA clones provide some of the first reagents for studying the molecular biology of human development.
Expression of tenascin in response to neural induction in amphibian embryos
Authors: Riou Jean-Francois , Shi De-Li , Chiquet Matthias , Boucaut Jean-Claude
Published: April 2021

The expression of tenascin, a constituent of extracellular matrix (ECM), was studied during the embryonic development of the amphibian Pleurodeles waltl. An antiserum to chick fibroblast tenascin was shown to cross-react with the homologous molecule of the amphibian. Immunostaining of embryo sections with anti-tenascin antiserum revealed that tenascin appears just after the completion of neurulation. At the tailbud stage, tenascin is present in the ECM located at sites of directed cell migration (neural crest cell migration pathways, extension of the pronephretic duct) and mesenchyme condensation (endocardium, aortic arches). The accumulation of tenascin immunoreactivity in the embryonic ECM is correlated with the synthesis of the 220×103A/r polypeptide of the molecule. To provide data on the patterning of tenascin, ectoderm and dorsal blastoporal lip isolated at early gastrula stage were cultured for a period of 3 days. Epidermal vesicles differentiating from isolated ectoderm completely lack tenascin. Conversely, axial mesoderm derivatives present in cultured dorsal blastoporal lip were found to produce tenascin. Neural induction of ectoderm isolated at early gastrula stage was performed in vitro with the dorsal blastoporal lip or concanavalin A. The induced neural tissue was found to accumulate tenascin. Spemann experiments confirmed in vivo that tenascin is expressed by ectodermal cells as a response to neural induction.
Requirement of cell division for muscle actin expression in the primary muscle cell lineage of ascidian embryos
Authors: Jeffery William R.
Published: April 2021

The role of cell division in the expression of muscle actin and its relationship to acetylcholinesterase (AChE) development was examined in cleavage-arrested embryos of the ascidian Styela. Muscle actin expression was detected by two-dimensional gel electrophoresis of radioactively labelled proteins and by in situ hybridization with a cDNA probe, whereas AChE activity was assayed by enzyme histochemistry. In the majority of cases, muscle actin expression was first detected in embryos arrested after the 16-cell stage. Some embryos showed muscle actin expression after arrest at the 8-cell stage, however, muscle actin mRNA did not accumulate in embryos arrested at earlier cleavages. The cells that expressed muscle actin in 8- to 64-cell cleavage-arrested embryos belonged to the primary muscle lineage; secondary muscle cell precursors did not express muscle actin. Zygotic muscle actin mRNA appeared to accumulate with myoplasmic pigment granules in the perinuclear region of cleavage-arrested embryos, suggesting that the myoplasm may have a role in the organization of muscle cells. In contrast to muscle actin, AChE was detected in a small proportion of embryos treated with cytochalasin as early as the 1- or 2-cell stage, and most embryos treated with cytochalasin at later cleavages expressed this enzyme in some of their cells. Most primary muscle lineage cells expressed both muscle actin mRNA and AChE, however, some cells expressed only muscle actin mRNA or AChE. The results suggest that at least three cleavages are required for muscle actin expression and that muscle actin and AChE expression can be uncoupled in cleavage-arrested embryos.