bluuebunny/crossref_metadata_2025 huggingface dataset:
Pretreatment with LCK inhibitors chemosensitizes cisplatin‐resistant endometrioid ovarian tumors
Authors: Crean-Tate Katie K. , Braley Chad , Dey Goutam , Esakov Emily , Saygin Caner , Trestan Alexandria , Silver Daniel J. , Turaga Soumya M. , Connor Elizabeth V. , DeBernardo Robert , Michener Chad M. , Rose Peter G. , Lathia Justin , Reizes Ofer
Published: April 2021

Background

Ovarian cancer is the most fatal gynecologic malignancy in the United States. While chemotherapy is effective in the vast majority of ovarian cancer patients, recurrence and resistance to standard systemic therapy is nearly inevitable. We discovered that activation of the non-receptor tyrosine kinase Lymphocyte Cell-Specific Protein-Tyrosine Kinase (LCK) promoted cisplatin resistance. Here, we hypothesized that treating high grade, platinum resistant endometrioid cancer cells with an LCK inhibitor (LCKi) followed by co-treatment with cisplatin would lead to increased cisplatin efficacy. Our objective was to assess clinical outcomes associated with increased LCK expression, test our hypothesis of utilizing LCKi as pre-treatment followed by co-treatment with cisplatin in platinum resistant ovarian cancer in vitro, and evaluate our findings in vivo to assess LCKi applicability as a therapeutic agent.

Results

Kaplan-Meier (KM) plotter data indicated LCK expression is associated with significantly worse median progression-free survival (HR 3.19, p = 0.02), and a trend toward decreased overall survival in endometrioid ovarian tumors with elevated LCK expression (HR 2.45, p = 0.41). In vitro, cisplatin resistant ovarian endometrioid cells treated first with LCKi followed by combination LCKi-cisplatin treatment showed decreased cell viability and increased apoptosis. Immunoblot studies revealed LCKi led to increased expression of phosphorylated H2A histone family X ($$\gamma$$
γ
-H2AX), a marker for DNA damage. In vivo results demonstrate treatment with LCKi followed by LCKi-cisplatin led to significantly slowed tumor growth.

Conclusions

We identified a strategy to therapeutically target cisplatin resistant endometrioid ovarian cancer leading to chemosensitization to platinum chemotherapy via treatment with LCKi followed by co-treatment with LCKi-cisplatin.
Lower variability in female students than male students at multiple timescales supports the use of sex as a biological variable in human studies
Authors: Smarr Benjamin L. , Ishami Annick Laure , Schirmer Aaron E.
Published: April 2021

Background

Men have been, and still are, included in more studies than women, in large part because of the lingering belief that ovulatory cycles result in women showing too much variability to be economically viable subjects. This belief has scientific and social consequences, and yet, it remains largely untested. Recent work in rodents has shown either that there is no appreciable difference in overall variability across a wealth of traits, or that in fact males may show more variability than females.

Methods

We analyzed learning management system logins associated to gender records spanning 2 years from 13,777 students at Northeastern Illinois University. These data were used to assess variability in daily rhythms in a heterogeneous human population.

Results

At the population level, men are more likely than women to show extreme chronotypes (very early or very late phases of activity). Men were also found to be more variable than women across and within individuals. Variance correlated negatively with academic performance, which also showed a gender difference. Whereas a complaint against using female subjects is that their variance is the driver of statistical sex differences, only 6% of the gender performance difference is potentially accounted for by variance, suggesting that variability is not the driver of sex differences here.

Conclusions

Our findings do not support the idea that women are more behaviorally variable than men and may support the opposite. Our findings support including sex as a biological variable and do not support variance-based arguments for the exclusion of women as research subjects.
Correction to: Identifying resting locations of a small elusive forest carnivore using a two-stage model accounting for GPS measurement error and hidden behavioral states
Authors: Hance Dalton J. , Moriarty Katie M. , Hollen Bruce A. , Perry Russell W.
Published: April 2021

An amendment to this paper has been published and can be accessed via the original article.
Laboratory evaluation of higher-order aberrations and light scattering in explanted opacified intraocular lenses
Authors: Łabuz Grzegorz , Yildirim Timur M. , Auffarth Gerd U. , Son Hyeck-Soo , Khoramnia Ramin
Published: April 2021

Background

Intraocular lens (IOL) calcification is a serious condition that can only be treated by removing the clouded lens. Since explantation bears the risk of complications, it is often deferred until the patient finds the symptoms intolerable. Usually, as the IOL opacifies, visual acuity is minimally affected early on. In this study, we assessed the impact of IOL opacification on optical quality.

Methods

We analyzed ten opacified explanted IOLs (Oculentis GmbH). Wavefront aberrations were obtained with a SHSOphthalmic device (Optocraft GmbH), which features a Hartmann-Shack sensor. The root mean square (RMS) of higher-order aberrations (HOAs) was compared. The effect of calcification on image quality was assessed through the Strehl ratio (SR). We detected light scattering with a C-Quant (Oculus GmbH) and expressed it as a straylight parameter.

Results

At 2 mm, 3 mm and 4 mm, the mean RMS (±standard deviation) was 0.033 μm (±0.026 μm), 0.044 μm (±0.027), and 0.087 μm (±0.049), respectively. The mean SR value was 0.81 ± 0.15 at 3 mm, with four IOLs showing a nearly diffraction-limited performance, but in two explants, opacification precluded reliable measurements. Increased straylight was found in all opacified IOLs with a mean value of 150.2 ± 56.3 deg2/sr at 3 mm.

Conclusions

We demonstrated that IOL opacification induces HOAs. However, the RMS remained low, which resulted only in a slight reduction of the SR-derived optical quality. On the other hand, we found a severe straylight elevation in the opacified lenses, which may result in dysphotopsia, such as glare, and subjective complaints, despite good visual acuity.
Point-of-care manufacturing: a single university hospital’s initial experience
Authors: Calvo-Haro Jose Antonio , Pascau Javier , Asencio-Pascual José Manuel , Calvo-Manuel Felipe , Cancho-Gil Maria José , Del Cañizo López Juan Francisco , Fanjul-Gómez María , García-Leal Roberto , González-Casaurrán Guillermo , González-Leyte Manuel , León-Luis Juan Antonio , Mediavilla-Santos Lydia , Ochandiano-Caicoya Santiago , Pérez-Caballero Ramón , Ribed-Sánchez Almudena , Río-Gómez Javier , Sánchez-Pérez Eduardo , Serrano-Andreu Javier , Tousidonis-Rial Manuel , Vaquero-Martín Javier , García San José Sonia , Perez-Mañanes Rubén
Published: April 2021

Background

The integration of 3D printing technology in hospitals is evolving toward production models such as point-of-care manufacturing. This study aims to present the results of the integration of 3D printing technology in a manufacturing university hospital.

Methods

Observational, descriptive, retrospective, and monocentric study of 907 instances of 3D printing from November 2015 to March 2020. Variables such as product type, utility, time, or manufacturing materials were analyzed.

Results

Orthopedic Surgery and Traumatology, Oral and Maxillofacial Surgery, and Gynecology and Obstetrics are the medical specialties that have manufactured the largest number of processes. Working and printing time, as well as the amount of printing material, is different for different types of products and input data. The most common printing material was polylactic acid, although biocompatible resin was introduced to produce surgical guides. In addition, the hospital has worked on the co-design of custom-made implants with manufacturing companies and has also participated in tissue bio-printing projects.

Conclusions

The integration of 3D printing in a university hospital allows identifying the conceptual evolution to “point-of-care manufacturing.”
Involvement of the endocannabinoid system in the inhibition of Sindbis virus replication: a preliminary study
Authors: Rodriguez Juan L. , Lopez Joseph A. , Steel J. Jordan
Published: April 2021

Background

Sindbis virus (Alphaviridae) is a plus-strand RNA virus that is dependent on the host cell for replication. Cannabinoid (CB) receptors are found on most human cells, including virally infected cells. Activation of cannabinoid receptors has been shown to alter normal cellular physiology. This study aimed to assess how agonist (ACEA) or antagonists/inverse agonist (AM251) of the cannabinoid receptors would alter the cellular environment and impact Sindbis virus replication.

Methods

Human hepatoma (Huh7) cells were used as our model for viral replication. Cells were infected with Sindbis virus (SINV) and then treated with CB agonist (ACEA) (10 μM) or antagonist/inverse agonist (AM-251) (10 μM) and virus replication was monitored. A double subgenomic Sindbis virus containing a green fluorescent protein (GFP) reporter gene inserted into a 3′ subgenomic promoter was utilized for these assays to quickly measure viral replication. GFP fluorescent cells were analyzed using flow cytometry to measure the percentage of cells expressing the viral reporter and also quantify the levels of GFP fluorescence.

Result

Treatment of SINV-infected Huh7 cells with CB1 receptor antagonist/inverse agonist (AM251, 10 μM) resulted in a significant decrease in viral replication, while infected cells treated with a CB1 receptor agonist (ACEA, 10 μM) resulted in a significant increase of viral infection. The data indicates that activation of CB1 receptor by cannabinoids significantly influences the ability of Sindbis virus to replicate in the host cell.

Conclusion

Blocking CB1 receptor activity with 10 μM AM251 reduced viral replication, but activating the CB1 receptor with 10 μM ACEA resulted in an increase in viral infection. These results indicate cannabinoids may significantly impact a virus replicating in human liver cells. Future confirmation with other viruses and cell lines will be performed to better understand the impact of cannabinoids on viral infections.
Host phylogeny and host ecology structure the mammalian gut microbiota at different taxonomic scales
Authors: Rojas Connie A. , Ramírez-Barahona Santiago , Holekamp Kay E. , Theis Kevin R.
Published: April 2021

The gut microbiota is critical for host function. Among mammals, host phylogenetic relatedness and diet are strong drivers of gut microbiota structure, but one factor may be more influential than the other. Here, we used 16S rRNA gene sequencing to determine the relative contributions of host phylogeny and host diet in structuring the gut microbiotas of 11 herbivore species from 5 families living sympatrically in southwest Kenya. Herbivore species were classified as grazers, browsers, or mixed-feeders and dietary data (% C4 grasses in diet) were compiled from previously published sources. We found that herbivore gut microbiotas were highly species-specific, and that host taxonomy accounted for more variation in the gut microbiota (30%) than did host dietary guild (10%) or sample month (8%). Overall, similarity in the gut microbiota increased with host phylogenetic relatedness (r = 0.74) across the 11 species of herbivores, but among 7 closely related Bovid species, dietary %C4 grass values more strongly predicted gut microbiota structure (r = 0.64). Additionally, within bovids, host dietary guild explained more of the variation in the gut microbiota (17%) than did host species (12%). Lastly, while we found that the gut microbiotas of herbivores residing in southwest Kenya converge with those of distinct populations of conspecifics from central Kenya, fine-scale differences in the abundances of bacterial amplicon sequence variants (ASVs) between individuals from the two regions were also observed. Overall, our findings suggest that host phylogeny and taxonomy strongly structure the gut microbiota across broad host taxonomic scales, but these gut microbiotas can be further modified by host ecology (i.e., diet, geography), especially among closely related host species.
The taxonomy, host range and pathogenicity of coronaviruses and other viruses in the Nidovirales order
Authors: Zhou Zhijian , Qiu Ye , Ge Xingyi
Published: April 2021

The frequent emergence of coronavirus (CoV) epidemics has seriously threatened public health and stock farming. The major hosts for CoVs are birds and mammals. Although most CoVs inhabit their specific natural hosts, some may occasionally cross the host barrier to infect livestock and even people, causing a variety of diseases. Since the beginning of the new century, increasing attention has been given to research on CoVs due to the emergence of highly pathogenic and genetically diverse CoVs that have caused several epidemics, including the recent COVID-19 pandemic. CoVs belong to the Coronaviridae family of the Nidovirales order. Recently, advanced techniques for viral detection and viral genome analyses have enabled characterization of many new nidoviruses than ever and have greatly expanded the Nidovirales order with new classification and nomenclature. Here, we first provide an overview of the latest research progress in the classification of the Nidovirales order and then introduce the host range, genetic variation, genomic pattern and pathogenic features of epidemic CoVs and other epidemic viruses. This information will promote understanding of the phylogenetic relationship and infectious transmission of various pathogenic nidoviruses, including epidemic CoVs, which will benefit virological research and viral disease control.
Electrical imaging of hydraulic fracturing fluid using steel-cased wells and a deep-learning method
Authors: Li Yinchu , Yang Dikun
Published: April 2021

Steel-cased wells used as long electrodes (LEs) in a surface-electric or electromagnetic survey can enhance anomalous signals from deep hydraulic fracturing zones filled by injected fluid. Although recent research has been published on the algorithms designed for the simulation of the effect of casings, feasibility studies on resolving the small-scale fracturing fluid flow from surface data are lacking. We have carried out a detectability and recoverability study for a top-casing electric source configuration. Applying a fast 3D DC modeling code using the concept of the equivalent resistor network, the detectability study shows that favorable conditions for detecting the fluid flow direction include multiple electrically coupled wells and different electric conductivities above and below the shale layer. The observed behavior is then modeled through a circuit analog. For the purpose of fracturing fluid imaging, the model for recovery is simplified as a distribution of full fluid saturation on a 2D fracture plane. A deep-learning (DL) framework is adopted to solve the imaging problem, which is difficult for conventional regularized inversions. Our DL implementation uses a supervised deep fully convolutional network to learn the relationship between data patterns on the surface and the model of fracturing fluid distribution, encoded in a large number of synthetic data-model pairs. Once trained, the neural network can make a real-time and pixel-wise prediction of the fluid distribution. The robustness of our DL approach is tested in the presence of ambient noise and inaccuracies in casing conductivity. A reasonably consistent prediction performance has been observed. Our numerical feasibility study results demonstrate that electric surveys using steel casings as LEs have great potentials in real-time monitoring of fracturing fluid flow.
Psychosocial stress and immunosuppression in cancer: what can we learn from new research?
Authors: Singh Anurag K. , Chatterjee Udit , MacDonald Cameron R. , Repasky Elizabeth A. , Halbreich Uriel
Published: April 2021

It is generally believed that the physiological consequences of stress could contribute to poor outcomes for patients being treated for cancer. However, despite preclinical and clinical evidence suggesting that stress promotes increased cancer-related mortality, a comprehensive understanding of the mechanisms involved in mediating these effects does not yet exist. We reviewed 47 clinical studies published between 2007 and 2020 to determine whether psychosocial stress affects clinical outcomes in cancer: 6.4% of studies showed a protective effect; 44.6% showed a harmful effect; 48.9% showed no association. These data suggest that psychosocial stress could affect cancer incidence and/or mortality, but the association is unclear. To shed light on this potentially important relationship, objective biomarkers of stress are needed to more accurately evaluate levels of stress and its downstream effects. As a potential candidate, the neuroendocrine signalling pathways initiated by stress are known to affect anti-tumour immune cells, and here we summarise how this may promote an immunosuppressive, pro-tumour microenvironment. Further research must be done to understand the relationships between stress and immunity to more accurately measure how stress affects cancer progression and outcome.
Increased prevalence of intellectual disabilities in higher-intensity mental healthcare settings
Authors: Nieuwenhuis Jeanet G. , Lepping Peter , Mulder Niels L. , Nijman Henk L. I. , Veereschild Mike , Noorthoorn Eric O.
Published: April 2021

Background

It has been suggested that people with intellectual disabilities have a higher likelihood to develop psychiatric disorders, and that their treatment prognosis is relatively poor.

Aims

We aimed to establish the prevalence of intellectual disability in different mental healthcare settings, and estimate percentage of cognitive decline. We hypothesised that the prevalence of intellectual disabilities increases with intensity of care.

Method

A cross-sectional study was conducted in different settings in a mental healthcare trust in the Netherlands. We used the Screener for Intelligence and Learning Disabilities (SCIL) to identify suspected mild intellectual disability (MID) or borderline intellectual functioning (BIF). We identified patients with a high level of education and low SCIL score to estimate which patients may have had cognitive decline.

Results

We included 1213 consecutive patients. Over all settings, 41.4% of participating patients were positive for MID/BIF and 20.2% were positive for MID only. Prevalence of suspected MID/BIF increased by setting, from 27.1% in out-patient settings to 41.9% in flexible assertive community treatment teams and admission wards, to 66.9% in long-stay wards. Only 85 (7.1%) of all patients were identified as possibly having cognitive decline. Of these, 25.9% were in long-stay wards and had a diagnosis of schizophrenia or substance use disorder.

Conclusions

Low intellectual functioning is common in Dutch mental healthcare settings. Only a modest number of patients were identified as suffering from cognitive decline rather than suspected MID/BIF from birth. Therefore, we recommend improved screening of psychiatric patients for intellectual functioning at the start of treatment.
Set-shifting-related basal ganglia deformation as a novel familial marker of obsessive–compulsive disorder
Authors: Isobe Masanori , Vaghi Matilde , Fineberg Naomi A. , Apergis-Schoute Annemieke M. , Bullmore Edward T. , Sahakian Barbara J. , Robbins Trevor W. , Chamberlain Samuel R.
Published: April 2021

The symptoms of obsessive–compulsive disorder (OCD) are suggestive of cognitive rigidity, and previous work identified impaired flexible responding on set-shifting tasks in such patients. The basal ganglia are central to habit learning and are thought to be abnormal in OCD, contributing to inflexible, rigid habitual patterns of behaviour. Here, we demonstrate that increased cognitive inflexibility, indexed by poor performance on the set-shifting task, correlated with putamen morphology, and that patients and their asymptomatic relatives had common curvature abnormalities within this same structure. The association between the structure of the putamen and the extradimensional errors was found to be significantly familial in OCD proband–relative pairs. The data implicate changes in basal ganglia structure linked to cognitive inflexibility as a familial marker of OCD. This may reflect a predisposing heightened propensity toward habitual response patterns and deficits in goal-directed planning.
Expanded Access and Right To Try Requests: The Community Oncologist's Experience
Authors: Zettler Marjorie E. , Jeune-Smith Yolaine , Feinberg Bruce A. , Phillips Eli G. , Gajra Ajeet
Published: April 2021

PURPOSE:

For patients with cancer who have exhausted approved treatment options and for whom appropriate clinical trials are not available, access to investigational drugs through the US Food and Drug Administration's Expanded Access (EA) program has been an alternative since the program's inception more than 30 years ago. In 2018, federal Right To Try legislation was passed in the United States, creating a second pathway—one that bypasses the US Food and Drug Administration—to obtain unapproved drugs outside of clinical trials. The use of the two programs by community medical oncologists and hematologist-oncologists has not been studied.

METHODS:

Between October 2019 and February 2020, community oncologists-hematologists from across the United States completed web-based surveys about EA and Right To Try pathways for accessing unapproved drugs for their patients. Physicians were asked about their utilization of, and perceptions of, the two programs.

RESULTS:

Of the 238 physicians who completed the survey, 46% indicated that they had attempted to gain access to an investigational drug for a patient using the EA program, whereas 14% reported attempting to use Right To Try pathway to obtain an unapproved drug for a patient. Eighty-nine percent of those who tried to use the EA program reported success in obtaining the investigational drug versus 73% of those who attempted to use the Right To Try pathway.

CONCLUSION:

Our survey found that most community oncologists-hematologists were aware of both the EA and Right To Try pathways, but there is room for improvement in understanding and utilization of the programs.
Model-Based Re-Examination of the Effectiveness of Tumor/Immunohistochemistry and Direct-to-Sequencing Protocols for Lynch Syndrome Case Finding in Endometrial Cancer
Authors: Gudgeon James M. , Varner Michael W. , Hao Jing , Williams Marc S.
Published: April 2021

PURPOSE:

Despite widespread provision of Lynch syndrome (LS) screening programs, questions remain about the most effective and efficient protocol for LS case finding. The purpose of this study was to explore the performance of the two protocols widely shown to be the most efficient and effective, respectively: immunohistochemical (IHC) staining of tumor and direct-to-sequencing (DtS) in endometrial cancer populations.

METHODS:

Simulation models were developed to explore performance of the IHC and DtS protocols, updated to reflect current evidence. Analyses explicitly account for protocol complexity and failure points, as well as decreased sequencing costs. Key outcomes are percent of LS cases identified, total protocol costs and efficiency, and break-even analyses of sequencing costs. All costs are in 2020 US dollars (USD).

RESULTS:

Under plausible conditions, the IHC protocol is expected to identify 40%-78% of LS cases and DtS protocol from 49% to 97%. When the key variable success in proceeding to sequencing is fixed for both protocols at 50%, 75%, and 100%, the DtS protocol is 9%, 12%, and 16% better at case finding, respectively, than the IHC protocol. The break-even cost of sequencing is about $488 USD when the outcome is total direct testing protocol costs; it is about $670 USD when the outcome is cost per LS case detected.

CONCLUSION:

This study quantifies the plausible differences in the clinical effectiveness and cost-effectiveness of the two LS case-finding protocols. We demonstrate the large influence of success in proceeding to sequencing and potential impact of decreasing sequencing prices.
Pseudoautosomal genes in man
Authors: Goodfellow P. J. , Darling S. , Banting G. , Pym B. , Mondello C. , Goodfellow P. N.
Published: April 2021

MIC2, which encodes the 12E7 antigen, is the only well-defined pseudoautosomal gene in man. We have isolated cDNA and genomic sequences corresponding to MIC2 and have produced monoclonal antibodies reacting with the 12E7 antigen. These molecular tools have been used to investigate the genetics and biochemistry of the MIC2 system. Recent results suggest that MIC2 is the most proximal of the currently defined pseudoautosomal markers and that the escape of M1C2 from X-inactivation may be intrinsic to an associated HTF island found at the 5’ end of the gene. Investigation of the inter-relationship between M1C2 and the XG locus has led us to postulate the existence of a second pseudoautosomal gene in man.
The use of Y-chromosome-specific repeated DNA sequences in the analysis of testis development in an XX/XY mouse
Authors: Singh Lalji , Matsukuma Shoichi , Jones K. W.
Published: April 2021

A study, by means of Y-chromosome-specific repeated DNA probes, of mouse (ST) with small testes is reviewed. Mouse ST was shown to be a somatic mosaic of 10 % XY and 90 % XX cells. The cellular composition of the azoospermie testis reflected the overall proportions of XX and XY cells but it was found that XY cells predominated in the Sertoli cells of the testis tubules. These findings have been interpreted to indicate a fundamental role for the Sertoli cell in inducing testis organization in the indifferent gonadal rudiment, involving the expression of the Y chromosome.
The Y-chromosomal and autosomal testis-determining genes
Authors: De La Chapelle Albert
Published: April 2021

It has been conclusively shown that a majority of XX males has acquired Y-chromosome-specific DNA (Y-DNA) sequences from their father’s Y chromosome. Testicular differentiation in these XX males is very likely induced by the testis-determining factor, TDF, normally located on Yp. The phenotypic expression of TDF in the presence of two X chromosomes is a male habitus, dysgenetic scrotal testes and no ambiguity of the genitalia.

Among those XX males who do not have Y-DNA detectable by presently used methods, some, but not all have ambiguity of the genitalia with or without hypospadias. XX true hermaphrodites are characterized by the presence of both testicular and ovarian tissue and have ambiguous genitalia. They do not have Y-DNA.

Several instances of familial XX maleness are critically analysed. In these pedigrees, most of the affected individuals are true hermaphrodites or XX males with ambiguous genitalia; in at least one family no Y-DNA occurred in these individuals. Typical autosomal dominant inheritance of XX testicular differentiation occurs in informative pedigrees. The suggested conclusion is that an autosomal dominant testis-determining factor, TDFA, exists. TDFA shows somewhat variable expression in XX individuals often causing genital ambiguity or true hermaphrodism. TDFA has no phenotypic effect on XY individuals. It is argued that XX males without presently detectable Y-DNA are caused either by TDF or TDFA.
Regeneration in the medial–lateral axis of the insect thoracic segment
Authors: French Vernon , Rowlands Tamara F.
Published: April 2021

We have studied pattern regulation in the medial-lateral axis of the insect segment by grafting legs of beetle larvae (Tenebrio molitor) in different orientations into different positions medial and lateral to the leg site. The Boundary Model and Polar Coordinate Model of the insect appendage predict various patterns of supernumerary leg regeneration, and these grafts were designed to test the predictions.

When a larval leg is grafted with normal anterior-posterior orientation medial to the normal leg, larvae and subsequent adults bear the graft plus a super-numerary leg. This is located where the lateral edge of the grafted leg confronted medial thorax (from the leg base across to the midline) and is orientated as a mirror image of the graft. The tarsal structure of supernumeraries resulting from grafts of the mesothoracic leg onto the metathorax shows that the supernumeraries may be derived from the graft, the host site or from both sources. Similarly, when a leg is grafted lateral to the leg site, a supernumerary forms at the confrontation between the medial edge of the graft and lateral thorax (from leg base across to the dorsal tergite). These results agree with the pre-dictions of both models and would indicate that the compartments or the positional values extend out from the leg to the midline and the edge of the tergite.

The two models differ in their predictions for the number, position and orientation of supernumeraries following 180° rotation of the grafted leg. When the rotated graft is placed lateral to the leg, larvae and adults form a single supernumerary which, in accordance with the Polar Coordinate Model, is lateral to the graft and orientated as a mirror image of it. However, the results of the corresponding medial graft cannot be readily explained by either model. Larvae form a single supernumerary either posterior or medial to the graft, suggesting a modified model with unequally spaced positional values, but the subsequent adult supernumeraries are almost all located medially.

Experiments involving a graft placed medial to the leg site frequently show duplication of the adult midline suture, an extra branch forming between the thorax and the graft or supernumerary leg. In this case, as in the regeneration of the dorsal midline, the extreme medial structure is formed between two more lateral regions, which need not come from opposite sides of the body, but must have opposite mediolateral polarities.

At present, no model can adequately explain all the results of grafting and extirpation on the insect ventral thorax.
Murine A type retroviruses promote high levels of gene expression in embryonal carcinoma cells
Authors: Morgan Richard A. , Christy Robert J. , Huang Ru Chih C.
Published: April 2021

The expression of Intracisternal A Particle (IAP) genes in the mouse embryonal carcinoma cell line PCC3 was investigated by cDNA cloning and transient gene expression assays. A group of 26 IAP cDNA clones, products of transcriptionally active IAP proviruses, were selected from a cDNA library made from undifferentiated PCC3 cell RNA. Several of these clones were characterized by restriction enzyme mapping and DNA sequence analysis. The DNA sequence in both the promoter and structural regions of two cDNAs closely resembles those of IAP genomic clones. Three new sequence elements were identified within the U3 region, an Spl transcription-factor-binding site, an adenovirus Ela enhancer sequence and a region of homology to a promoter element of adenovirus E4 gene. Hybrid constructs were made that place the U3/R region of the IAP cDNAs immediately 5’ to the chloramphenicol acetyl transferase (CAT) gene. IAP-CAT constructs were transfected into PCC3 cells, and cell extracts prepared and analysed for CAT enzyme activity and CAT RNA levels. IAP-CAT transfected cells were shown to contain substantial levels of CAT enzyme activity and to accumulate much greater levels of CAT RNA than two standard promoters, pRSVcat and pSVlcat. The ability of these A type retroviral promoters to function in PCC3 cells is in direct contrast to the near total restriction of normal C type retroviral expression in EC cells.
The role of diffusible molecules in regulating the cellular differentiation ofDictyostelium discoideum
Authors: Williams Jeffrey G.
Published: April 2021

A central problem in developmental biology is to understand how morphogenetic fields are created and how they act to direct regionalized cellular differentiation. This goal is being pursued in organisms as diverse as moulds, worms, flies, frogs and mice. Each organism has evolved its own solution to the challenge of multicellularity but there appear to be common underlying principles and, once pattern formation is fully understood in any system, some general truths seem certain to be revealed. As a non-obligate metazoan, Dictyostelium discoideum has proven a particularly tractable system in which to identify and characterize cellular morphogens. Cyclic AMP and ammonia stimulate prespore cell differentiation and ammonia plays an additional role in repressing terminal cellular differentiation. Differentiation Inducing Factor (DIF) acts to direct prestalk cell differentiation and adenosine may play a synergistic role in repressing prespore cell differentiation. This review summarizes the evidence for these interactions and describes a number of models which show how this small repertoire of diffusible molecules, acting in concert, may direct the formation of a differentiated structure.
Microamputation of somatic embryos of the domestic carrot reveals apical control of axis elongation and root regeneration
Authors: Schiavone F. Mark
Published: April 2021

Somatic heart- and torpedo-stage embryos of the domesticated carrot, Daucus carota L., were severed at their midlengths to produce two halves termed apical and basal pieces. These pieces may be grafted or kept separate. Grafted embryos developed normally, with the exception that they tended to mature earlier than uncut control embryos. If kept separate, the apices grew at rates similar to grafted apices, while the basal ends, behaving as if they had been released from an inhibition of growth, rapidly elongated and matured (e.g. produced root hairs and a root cap) 3–4 days earlier than uncut controls. Grafted embryos treated with the transport inhibitor TIBA (2,3,5triiodobenzoic acid) had basal sections that behaved as if the sections had been kept separate. Additionally, resupplying IAA (indole-3-acetic acid) via a novel wick-bridge forced isolated basal pieces to behave as if the embryo apex were present. This apparent inhibition of root growth by the apex appears to be controlled by either the polar transport of auxin, and/or the accumulation of auxin at the root end. These experiments suggest that polar auxin transport has a greater influence on root, rather than on apex, development in these embryos.
Transcripts of α-cardiac and α-skeletal actins are early markers for myogenesis in the mouse embryo
Authors: Sassoon David A. , Garner Ian , Buckingham Margaret
Published: April 2021

Among the first tissues to differentiate in the mammalian embryo are cardiac and subsequently skeletal striated muscle. We have developed specific cRNA probes corresponding to the 5′ noncoding regions of α-cardiac and α-skeletal actin mRNAs in order to investigate myogenesis in the mouse embryo. Transcripts coding for cardiac actin which is the major isoform of the adult heart can first be detected between 7·5 and 7·8 days p.c. in the developing heart and are observed in all somites as they are formed. In addition, α-skeletal actin transcripts are accumulated at much lower levels in cardiac tissue and newly formed somites; both heart and skeletal muscle show co expression of this actin gene pair at all stages of development examined. The fact that cardiac actin transcripts can be observed in the myotomal portion of the somite prior to muscle fibre differentiation indicates that cardiac actin transcripts (and to a lesser extent skeletal actin transcripts) are markers not only of striated muscle tissue, but also of earlier stages of the myogenic programme in vivo.
Calcium localization duringAcetabulariawhorl formation: evidence supporting a two-stage hierarchical mechanism
Authors: Harrison Lionel G. , Graham Keith T. , Lakowski Bernard C.
Published: April 2021

The giant single-celled marine alga Acetabularia mediterranea (or A. acetabulum) repeatedly generates whorls of hairs at its growing tip. Theoretical considerations, and physicochemical analysis of the effect of extracellular calcium concentration on hair spacing, have suggested a two-stage mechanism, in which whorl pattern is preceded by a simple annular pattern. This analysis requires that, at the time of whorl determination, morphogenetically related calcium should still be distributed in the first-stage annular pattern. This paper reports studies of calcium distribution at closely spaced developmental stages from unpatterned growing tip to whorl expression. The sequence observed is that expected from the theoretical analysis. The fluorescence chelate used, chloro tetracycline, is believed to be specific for membrane-bound calcium. The results therefore suggest, but do not prove, that morphogenetically related calcium is attached to membrane-bound structures rather than Intracellular ones.
IGF-2 receptors are first expressed at the 2-cell stage of mouse development
Authors: Harvey Mark B. , Kaye Peter L.
Published: April 2021

A specific IGF-2 receptor antiserum was used to reveal the presence of IGF-2 receptors during preimplantation development of mice. Receptors were present on 2-, 4- and 8-cell embryos, morulae, blastocysts, and on ICMs isolated prior to staining. There was no evidence for receptors on fertilized eggs. These observations confirm reports of the expression of IGF-2 receptor mRNA as early as the 2-cell stage and refine similar observations in blastocysts to confirm expression in both the TE and ICM. A potential auto/paracrine loop is thus one of the first products of activation of the embryonic genome and is expressed constitutively through preimplantation development.
Survival of XO mouse fetuses: effect of parental origin of the X chromosome or uterine environment?
Authors: Hunt Patricia A.
Published: April 2021

Using a recombinant product from the structurally abnormal Y chromosome, Y*, female mice with a single X of either maternal or paternal origin were generated. The two types of females were produced on the same genetic background and differ only in the origin of the X chromosome. Hence it has been possible to assess the effect of parental origin of the X on survival of females with a single X chromosome. A highly significant prenatal loss of females with a single X of paternal origin, but no comparable loss of females with a single X of maternal origin was observed. The reduced viability of females with a paternally derived X could be mediated by the parental origin of the X (i.e. X chromosome imprinting) or alternatively, since the mothers of females with a single paternally derived X have only a single X chromosome, the effect could be mediated by the genotype of the mother (l.e. maternal uterine effect).
Positional cues governing cell migration in leech neurogenesis
Authors: Torrence Steven A.
Published: April 2021

The stereotyped distribution of identified neurons and glial cells in the leech nervous system is the product of stereotyped cell migrations and rearrangements during embryogenesis. To examine the dependence of longdistance cell migrations on positional cues provided by other tissues, embryos of Theromyzon rude were examined for the effects of selective ablation of various embryonic cell lines on the migration and final distribution of neural and glial precursor cells descended from the bilaterally paired ectodermal cell lines designated q bandlets. The results suggest that neither the commitment of q-bandlet cells to migrate nor the general lateral-to-medial direction of their migration depend on interactions with any other cell line. However, the ability of the migrating cells to follow their normal pathways and to find their normal destinations does depend on interactions with cells of the mesodermal cell line, which appears to provide positional cues that specify the migration pathways.
Developmental and spatial regulation of a Dictyostelium prespore gene: cis-acting elements and a cAMP-induced, developmentally regulated DNA binding activity
Authors: Haberstroh Linda , Galindo Jose , Firtel Richard A.
Published: April 2021

Previously, 5′ deletion analysis revealed three important upstream regions within the regulatory region of the cAMP-induced, prespore gene SP60 of D. discoidium, each of which contains a CA-rich sequence element (CAE: consensus CACACAYYYCACACAAA/T). In this study, we have made site-directed mutations within these CAEs and examined their effect on reporter gene activity (luciferase or lacZ). Point mutations within or deletion of the distal CAE (CAE-1), middle CAE (CAE-2) or proximal CAE (CAE-3) result in substantial decreases in promoter activity at 18 h of development or in response to cAMP. lacZ fusions made with the CAE mutant promoters produced novel β-gal staining patterns that suggest the presence of one or more morphogen gradients within the prespore zone of the slug and indicate that the CAEs are also important in regulating the spatial patterning of SP60 expression in the multicellular aggregate.

Gel mobility shift assays were used to identify activities from crude nuclear extracts that bind oligonucleotides containing the CAEs. One of the binding activities is not observed in extracts from vegetative cells or cells in early development and is induced during multicellular development with kinetics similar to those of SP60 gene expression. This activity is also induced in response to cAMP and specifically binds the wild-type CAE-1- and CAE-2-containing oligonucleotides. CAE-1 and CAE-2 oligonucleotides containing point mutations within the CAE core sequence neither bind to nor compete for the cAMP-induced, developmentally regulated factor(s) and result in substantial reductions in expression levels when substituted for the wild-type CAEs in vivo. The correlation between in vitro binding and in vivo function suggests that the CAE-l/CAE-2 binding activity may be involved in regulating cAMP and developmentally induced expression of SP60. A second, constitutive in vitro binding activity with high affinity to CAE-3 is also described. Models are proposed to relate the binding activities with the effects of the mutations on the spatial patterning of SP60-lacZ expression.
Budding-specific lectin induced in epithelial cells is an extracellular matrix component for stem cell aggregation in tunicates
Authors: Kawamura Kazuo , Fujiwara Shigeki , Sugino Yasuo M.
Published: April 2021

We have examined immunocytochemically the expression, localization and in vivo function of a calciumdependent and galactose-binding 14 ×103Mr lectin purified from the budding tunicate, Polyandrocarpa misakiensis. Lectin granules first appeared in the inner epithelium of a double-walled bud vesicle. Soon after the bud entered the developmental phase, the granules were secreted into the mesenchymal space, where the lectin-positive extracellular matrix (ECM) developed. The lectin was also produced and secreted by granular leucocytes during budding. Hemoblasts, pluripotent stem cells in the blood, were often found in association with the ECM and they aggregated with epithelial cells to form organ rudiments. The lectin showed a high binding affinity for hemoblast precursors. The blockage of epithelial transformation of stem cells by galactose in in vivo bioassay was ineffective in the presence of the lectin. Polyclonal anti-lectin antibody prevented the hemoblasts spreading on the ECM and moving toward the epithelium, but it did not block the cell–cell adhesion of hemoblasts. By three days of bud development, lectin granules and ECM have almost disappeared from the developing bud together with a cessation of hemoblast aggregation. These results show that Polyandrocarpa lectin is a component of the ECM induced specifically in budding and suggest strongly that it plays a role in bud morphogenesis by directing the migration of pluripotent stem cells to the epithelium.
Microinjection of fluorescent tracers to study neural cell lineages
Authors: Wetts Richard , Fraser Scott E.
Published: April 2021

The examination of cell lineages is an important step towards understanding the developmental events that specify the various cell types in the organism. The mechanisms that control which cell types are formed, their locations, and their numbers remain unknown. Analyses of cell lineage in the frog neural retina have revealed that individual precursors are multipotent and are capable of producing almost any combination of cell types. In addition to giving rise to a wide range of phenotypes, the precursors can give rise to a wide range of clone sizes. Cell lineage studies in other systems indicate that some precursors are multipotent, like those in the retina, while others appear to produce a more restricted range of descendants, perhaps even a single phenotype. These differences in the developmental potential of precursor cells suggest that the nervous system uses several strategies for producing its many cell types. Investigation of these strategies, at the cellular and molecular level, requires more than a description of the normal cell lineages. We are now exploiting the frog neural retina to perform the experimental manipulations needed to elucidate these strategies.
Cell lineage analysis of the avian neural crest
Authors: Bronner-Fraser Marianne , Fraser Scott E.
Published: April 2021

Neural crest cells migrate extensively and give rise to diverse cell types, including cells of the sensory and autonomic nervous systems. A major unanswered question concerning the neural crest is when and how the neural crest cells become determined to adopt a particular fate. We have explored the developmental potential of trunk neural crest cells in avian embryos by microinjecting a vital dye, lysinated rhodamine dextran (LRD), into individual cells within the dorsal neural tube. We find that premigratory and emigrating neural crest cells give rise to descendants with distinct phenotypes in multiple neural crest derivatives. These results are consistent with the idea that neural crest cells are multipotent prior to their emigration from the neural tube and become restricted in phenotype after emigration from the neural tube either during their migration or at their sites of localization. To determine whether neural crest cells become restricted during their migration, we have microinjected individual trunk neural crest cells with dye shortly after they leave the neural tube or as they migrate through the somite. We find that a majority of the clones derived from migrating neural crest cells appear to be multipotent; individual migrating neural crest cells gave rise to both sensory and sympathetic neurons, as well as cells with the morphological characteristics of Schwann cells, and other nonneuronal cells. Even those clones contributing to only one neural crest derivative often contained both neurofilament-positive and neurofilament-negative cells. These data demonstrate that migrating trunk neural crest cells, like their premigratory progenitors, can be multipotent. They give rise to cells in multiple neural crest derivatives and contribute to both neuronal and non-neuronal elements within a given derivative. Thus, restriction of neural crest cell fate must occur relatively late in migration or at the final destinations.