bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic review of the use of translated patient-reported outcome measures in cancer trials
Authors: Slade A. L. , Retzer A. , Ahmed K. , Kyte D. , Keeley T. , Armes J. , Brown J. M. , Calman L. , Gavin A. , Glaser A. W. , Greenfield D. M. , Lanceley A. , Taylor R. M. , Velikova G. , Turner G. , Calvert M. J.
Published: April 2021

Background

Patient-reported outcomes (PROs) are used in clinical trials to assess the effectiveness and tolerability of interventions. Inclusion of participants from different ethnic backgrounds is essential for generalisability of cancer trial results. PRO data collection should include appropriately translated patient-reported outcome measures (PROMs) to minimise missing data and sample attrition.

Methods

Protocols and/or publications from cancer clinical trials using a PRO endpoint and registered on the National Institute for Health Research Portfolio were systematically reviewed for information on recruitment, inclusion of ethnicity data, and use of appropriately translated PROMs. Semi-structured interviews were conducted with key stakeholders to explore barriers and facilitators for optimal PRO trial design, diverse recruitment and reporting, and use of appropriately translated PROMs.

Results

Eighty-four trials met the inclusion criteria, only 14 (17%) (n = 4754) reported ethnic group data, and ethnic group recruitment was low, 611 (13%). Although 8 (57%) studies were multi-centred and multi-national, none reported using translated PROMs, although available for 7 (88%) of the studies.

Interviews with 44 international stakeholders identified a number of perceived barriers to ethnically diverse recruitment including diverse participant engagement, relevance of ethnicity to research question, prominence of PROs, and need to minimise investigator burden. Stakeholders had differing opinions on the use of translated PROMs, the impact of trial designs, and recruitment strategies on diverse recruitment. Facilitators of inclusive research were described and examples of good practice identified.

Conclusions

Greater transparency is required when PROs are used as primary or secondary outcomes in clinical trials. Protocols and publications should demonstrate that recruitment was accessible to diverse populations and facilitated by trial design, recruitment strategies, and appropriate PROM usage. The use of translated PROMs should be made explicit when used in cancer clinical trials.
Current advances of epigenetics in periodontology from ENCODE project: a review and future perspectives
Authors: Cho Young-Dan , Kim Woo-Jin , Ryoo Hyun-Mo , Kim Hong-Gee , Kim Kyoung-Hwa , Ku Young , Seol Yang-Jo
Published: April 2021

Background

The Encyclopedia of DNA Elements (ENCODE) project has advanced our knowledge of the functional elements in the genome and epigenome. The aim of this article was to provide the comprehension about current research trends from ENCODE project and establish the link between epigenetics and periodontal diseases based on epigenome studies and seek the future direction.

Main body

Global epigenome research projects have emphasized the importance of epigenetic research for understanding human health and disease, and current international consortia show an improved interest in the importance of oral health with systemic health. The epigenetic studies in dental field have been mainly conducted in periodontology and have focused on DNA methylation analysis. Advances in sequencing technology have broadened the target for epigenetic studies from specific genes to genome-wide analyses.

Conclusions

In line with global research trends, further extended and advanced epigenetic studies would provide crucial information for the realization of comprehensive dental medicine and expand the scope of ongoing large-scale research projects.
Repeat individualized assessment using isomorphic questions: a novel approach to increase peer discussion and learning
Authors: Millar Russell , Manoharan Sathiamoorthy
Published: April 2021

It is demonstrated that the fully automatic generation of isomorphic questions allows for both repeat assessment, and for this assessment to be individualized. While this does require a substantial up-front effort, once prepared assessments can be reproduced with relative ease and with a near-zero probability of students receiving the same question a second time. We show the effectiveness of this approach using survey and performance data obtained from large year 2 and year 3 computer science classes. A greater than 10-fold increase in online peer discussion was observed, compared to the previous year. Contents analysis of the surveys showed that repeat testing was generally regarded favourably. Quantitative analyses found that prior homework did little to improve initial test performance, but was of vital importance in studying for the follow-up isomorphic test. Moreover, the performance gain on the isomorphic questions was the same for all students regardless of their overall ability, and was retained in the final exam.
Harmonizing evidence-based practice, implementation context, and implementation strategies with user-centered design: a case example in young adult cancer care
Authors: Haines Emily R. , Dopp Alex , Lyon Aaron R. , Witteman Holly O. , Bender Miriam , Vaisson Gratianne , Hitch Danielle , Birken Sarah
Published: April 2021

Background

Attempting to implement evidence-based practices in contexts for which they are not well suited may compromise their fidelity and effectiveness or burden users (e.g., patients, providers, healthcare organizations) with elaborate strategies intended to force implementation. To improve the fit between evidence-based practices and contexts, implementation science experts have called for methods for adapting evidence-based practices and contexts and tailoring implementation strategies; yet, methods for considering the dynamic interplay among evidence-based practices, contexts, and implementation strategies remain lacking. We argue that harmonizing the three can be facilitated by user-centered design, an iterative and highly stakeholder-engaged set of principles and methods.

Methods

This paper presents a case example in which we used a three-phase user-centered design process to design and plan to implement a care coordination intervention for young adults with cancer. Specifically, we usedusability testingto redesign and augment an existing patient-reported outcome measure that served as the basis for our intervention to optimize its usability and usefulness,ethnographic contextual inquiryto prepare the context (i.e., a comprehensive cancer center) to promote receptivity to implementation, and iterativeprototyping workshops with a multidisciplinary design teamto design the care coordination intervention and anticipate implementation strategies needed to enhance contextual fit.

Results

Our user-centered design process resulted in the Young Adult Needs Assessment and Service Bridge (NA-SB), including a patient-reported outcome measure and a collection of referral pathways that are triggered by the needs young adults report, as well as implementation guidance. By ensuring NA-SB directly responded to features of users and context, we designed NA-SBfor implementation, potentially minimizing the strategies needed to address misalignment that may have otherwise existed. Furthermore, we designed NA-SBfor scale-up; by engaging users from other cancer programs across the country to identify points of contextual variation which would require flexibility in delivery, we created a tool intended to accommodate diverse contexts.

Conclusions

User-centered design can help maximize usability and usefulness when designing evidence-based practices, preparing contexts, and informing implementation strategies—in effect, harmonizing evidence-based practices, contexts, and implementation strategies to promote implementation and effectiveness.
Intercellular Relations in the Development of Amphibian Pigmentation
Authors: Twitty Victor C.
Published: April 2021

The role of intercellular influences in the control of differentiation finds many illustrations in the development of amphibian pigmentation. From the time the chromatophores leave the neural crest as colourless, amoeboid cells, until they come to rest as differentiated elements of the distinctive pigment pattern, their developmental behaviour is conditioned throughout by effects exerted mutually by the chromatophores themselves or imposed upon them by the cells of neighbouring tissues. For the purposes of the present discussion, I shall limit myself to examples of intercellular relations affecting (1) the migration of chromatoblasts and (2) their synthesis of pigment.
Influence of Certain Substances on the Fluidity of the Cytoplasm and the Fertilizability of the Egg of the Sea-urchin, Psammechinus miliaris
Authors: Wicklund Elsa , Kriszat Georg , Runnström John
Published: April 2021

After nuclear maturation the eggs of Psammechinus (Ps.) miliaris are still ‘underripe’ with respect to their cytoplasm. This phenomenon is particularly conspicuous in Ps. miliaris from the Swedish west coast (see, for a summary, Runnström, 1949). In the small individuals of Ps. miliaris dredged from a depth of 30–40 metres this state of underripeness may last for months, so that full cytoplasmic maturity may be reached only in the latter half of August (Lindahl & Runnström, 1929). The littoral form of Ps. miliaris, on the other hand, has already attained cytoplasmic maturity in the latter half of June. Temperature conditions evidently play a decisive role in the phenomenon.
Inter-specific Transfers of Eggs Between Rat and Mouse
Authors: Tarkowski Andrzej K.
Published: April 2021

Mouse 2- and 8-cell and rat 2-, 4-, and 8-cell eggs develop into blastocysts when reciprocally transferred to the oviduct of the other species. Some rat eggs, after attaining the blastocyst stage in the mouse oviduct, do not shed the zona pellucida at the normal time and continue to increase in volume beyond the normal. This is accompanied by spreading of cells of the inner mass beneath the trophoblast, leaving the blastocyst without any compact embryonic structure. Other eggs develop into normal blastocysts with an inner cell mass present. Mouse eggs in the rat give rise to normally built blastocysts. Both kinds of rat blastocysts—hollow and normal—and mouse blastocysts evoke a typical decidual reaction in the uterus of the foreign species. Normal crypts are formed with the blastocysts attached to the epithelium. These processes begin well before any changes in the uterine epithelium become visible. The blastocysts of neither species are able to secure a normal contact with the mucosa. Degeneration of the epithelium under the influence of the trophoblast is delayed, irregular, and only small areas are involved. In the mouse, the eventual denudation of the mucosa around the blastocyst is thought to be largely an effect of spontaneous degeneration of the epithelium due to oedomatous changes in the underlying mucosa. The survival of mouse and rat blastocysts after implantation is very limited, the upper time limit being, in the mouse, the 7th day and, in the rat, the 8th day. Those rat blastocysts which have succeeded in establishing a contact with the mucosa undergo some differentiation, i.e. form small egg cylinders. This is accompanied by growth which in some cases is, however, very slight. Mouse blastocysts in the most successful cases exhibit immense increase in size but neither differentiation nor growth have been observed in their inner cell masses. The kidney surface of both species provides a favourable environment for the development of rat and mouse blastocysts reciprocally transferred. The trophoblast gives rise to numerous giant cells. The cells presumably of ‘inner mass’ origin are also visible, but organized embryonic development has not been observed. A number of rat eggs which developed into blastocysts in the mouse were re-transferred to rat recipients. The subsequent mortality rate was very high. Three purely trophoblastic vesicles were encountered and it is believed that they have developed from hollow blastocysts. These findings are discussed in the light of embryology and reproductive physiology.
Spinal neurite reabsorption and regrowth in vitro depend on the polarity of an applied electric field
Authors: McCaig Colin D.
Published: April 2021

Retraction and regrowth of frog neural tube neurites have been studied in vitro in control cultures and in the presence of a small, continuously applied electrical field. In control cultures, some degree of retraction was seen in 39 % of neurites while 7 % were reabsorbed completely. Reabsorption of anodalfacing neurites was at least twice as common, with 67 % showing some retraction and 17 % almost totally reabsorbed. Cathodal-facing neurites were spared from retraction. Following extreme reabsorption of anodal-facing neurites, reversal of the electric field promoted regeneration in 47 % (9/19) of cases studied.

Growth cone morphology also was determined by the polarity of the applied field. Anodal-facing growth cones had fewer filopodia than cathodal-facing growth cones sharing the same cell body. Field reversal induced a polarity-specific change in filopodia number on individual growth cones: a shift from anodal to cathodal increased filopodia numbers and vice versa. Some possible mechanisms involved and the significance of these results are discussed.
An analysis of cell shape and the neuroepithelial basal lamina during optic vesicle formation in the mouse embryo
Authors: Svoboda Kathy K. H. , O’Shea K. Sue
Published: April 2021

The optic vesicle develops as an evagination of the cephalic neural folds. We have examined the early development of the optic vesicle in Swiss Webster mice using correlated transmission electron microscopy (TEM), scanning electron microscopy (SEM), light microscopic (LM) measurements of cell shape changes, immunohistochemical localization of basal lamina (BL) components (type IV collagen, laminin and heparan sulphate proteoglycan (HSPG)) and ultrastructural analysis of the BL.

Like the neuroepithelium in other regions, the low columnar cells of the neural plate in the future optic vesicle region become high columnar, then wedge shaped following constriction of the cell apices to form the C-shaped vesicle. In this region, the cells elongate 2 times their initial height before the neural tube closes, then shorten 20 % as the vesicle is completed. Cell apices decrease in width by about one half during vesicle formation. Deposition of BL components was initially even, with type IV collagen and laminin reduced in deposition in regions of outpouching. At later stages the linear, even distribution of all four components was re-established. Ultrastructural analysis confirmed the BL discontinuity and re-establishment and correlated the observed cell shaping alterations with apparent increases in the number of microtubules (during elongation) and microfilaments (during apical constriction). The number of apical intercellular junctions also appeared to increase in number during optic vesicle formation, possibly providing stability and coordination to the évagination process.
Expression of Drosophila epidermal growth factor receptor homologue in mitotic cell populations
Authors: Kammermeyer K. L. , Wadsworth Samuel C.
Published: April 2021

Expression of the Drosophila homologue (DER) of the human epidermal growth factor (EGF) receptor has been studied during development by RNA blot hybridizations and in situ hybridizations. One of the hypothetical functions of the protein encoded by this gene is mitotic signal transduction and, therefore, we have searched for evidence of its expression in mitotic cell populations. Increased DER transcript levels were detected in virtually all cells in cellular blastoderm embryos, indicative of the onset of transcription of the gene at this stage of development. These transcripts persist at least until the formation of the ventral furrow at the beginning of gastrulation. Expression of DER has been investigated in populations of nondividing cells, imaginal cells and nervous tissue in third instar larvae. By RNA blot hybridizations, we have shown that imaginal discs contain the bulk of the DER transcripts present in the whole third instar larvae. This result has been confirmed by in situ hybridizations. All imaginal discs, representing dividing cells, contain DER transcripts while salivary glands, representing nondividing cells, do not. Within the central nervous system, hybridization of the DER probe is confined to small clusters of cells in the brain cortex. During oogenesis, cell division programs are highly ordered temporally and spatially. Follicle cells express high levels of DER RNA during their mitotic phase of growth but lose these transcripts as they cease division. Nurse cells also express DER transcripts at lower levels even though they are not dividing. However, nurse cell transcripts represent stored maternal RNA species destined for use during preblastoderm embryonic development. These results indicate that the DER gene is expressed in mitotic cell populations during several stages of development and is not expressed in certain populations of nonmitotic cells.
Genetics of cell and axon migrations in Caenorhabditis elegans
Authors: Hedgecock Edward M. , Culotti Joseph G. , Hall David H. , Stern Brian D.
Published: April 2021

The Caenorhabditis elegans epidermis comprises 78 cells which cover the external surface of the embryo as a single cell layer. These cells secrete the cuticle from their exterior faces and support the body wall muscles and most of the nervous system on their interior faces. The epidermal cells arise by autonomous embryonic cell lineages but show regulative interactions after their assembly into an epithelium. It is believed that the various epidermal cells express different kinds or amounts of surface molecules that govern their mutual assembly and also guide the attachments and migrations of the underlying body muscles and neurones. The first muscles and neurones may in turn express new surface molecules that refine later cell movements. Mutations in some 30 known genes disrupt the movements of cells or axons along the body wall.
In vitro analysis of glucose metabolism and embryonic growth in postimplantation rat embryos
Authors: Ellington S. K. L.
Published: April 2021

The glucose metabolism and embryonic development of rat embryos during organogenesis was studied using embryo culture. Glucose uptake and embryonic growth and differentiation of 10·5-day explants (embryos + membranes) were limited by the decreasing glucose concentration, but not the increasing concentration of metabolites, in the culture media during the second 24 h of a 48 h culture. No such limitations were found on the embryonic development of 9–5-day explants during a 48 h culture although glucose uptake was slightly reduced at very low concentrations of glucose. From the head-fold stage to the 25-somite stage of development, glucose uptake was characteristic of the stage of development of the embryo and not the time it had been in culture.

Embryonic growth of 9·5-day explants was similar to that previously observed in vivo. Glucose uptake by 9·5-day explants was dependent on the surface area of the yolk sac and was independent of the glucose concentration in the culture media (within the range of 9·4 to 2·5 mM). The proportion of glucose converted to lactate was 100 % during the first 42 h of culture then fell to about 50 % during the final 6 h. The protein contents of both the extraembryonic membranes and the embryo were dependent on the glucose uptake.
The monoclonal antibody 69A1 recognizes an epitope found on neurones with axons that fasciculate but not on those with non-fasciculating processes
Authors: Pigott R. , Davies A. M.
Published: April 2021

We have previously reported that the cell-type distribution and pattern of expression of the surface antigen recognized by the monoclonal antibody 69A1, suggests that it may be involved during the period of nerve fibre outgrowth and the formation of fibre bundles in the rat (Pigott & Kelly, 1986). In this current study, we have examined the expression of the epitope recognized by antibody 69A1 in regions of the rat central nervous system in which it is possible to distinguish between neurones with axons that fasciculate to form clearly defined fibre tracts and neurones with non-fasciculating processes. We have also examined antibody 69Al labelling in several regions of the peripheral nervous system. We report that the 69A1 epitope is expressed on neurones with axons that fasciculate but is not found on neurones with short, non-fasciculating axons or on neurones without a morphologically identifiable axon. The antigen 69Al has been purified and shown to be immunochemically closely related or identical to the LI antigen.
Computer-assisted analysis of hyaluronate distribution during morphogenesis of the mouse secondary palate
Authors: Brinkley Linda L. , Morris-Wiman Joyce
Published: April 2021

Hyaluronate mediated extracellular matrix swelling has been hypothesized to play a major role in reorientation of the secondary palatal shelves. A computer-assisted method utilizing image registration and subtraction was used to visualize the distribution of hyaluronate (HA) during morphogenesis of the secondary palate. Patterns of HA distribution in anterior, posterior and presumptive soft palate were examined in the secondary palatal shelves of CD-I mouse fetuses that were 30, 24 and 18 h prior to, and at the time of, shelf reorientation. Adjacent serial sections were taken from each shelf region of three to six specimens from a minimum of three litters for each gestational age. One section was incubated in buffer as a control, the other digested with Streptomyces hyaluronidase to specifically remove HA. Both sections were stained with Alcian blue to visualize the extracellular matrix and counterstained with nuclear fast red to visualize cells. Two different videoimages were then digitized for each tissue section, one using wavelengths of light that were at or near the maximum absorbance of the matrix stain, the other using wavelengths that were at the maximum absorbance of the cellular stain. Thus, a matrix image and a cell image of both control and digested sections were produced. Next, the cell image was subtracted from its respective matrix image, resulting in a control matrix-only image and a digested (HA-removed) matrix-only image. These images were mathematically warped to one another, if necessary, and registered with one another. The digested image was then subtracted from the control image. The resultant difference picture displayed the pattern and relative intensities of HA distribution across the tissue section. Prior to and during shelf reorientation, unique region-specific patterns of HA distribution and relative intensity were identified which became homogeneous after reorientation. Presumptive soft palate shows the most extensive and intense patterns of HA distribution, followed by the posterior region. The anterior region has the most sparse pattern of the three regions examined. The results are consistent with the hypothesized role of HA in shelf reorientation.
Effects of chlorcyclizine-induced glycosaminoglycan alterations on patterns of hyaluronate distribution during morphogenesis of the mouse secondary palate
Authors: Brinkley Linda L. , Morris-Wiman Joyce
Published: April 2021

Chlorcyclizine (CHLR) enhances the degradation of hyaluronate (HA) into smaller molecular weight pieces with no effect on its synthesis. Administration of CHLR to pregnant CD-I mice on gestational days 10·5, 11·5 and 12·5 results in 100 % cleft palate in the fetuses. The caudal two thirds of the palatal shelves are reduced in size and unable to reorient in vitro, while anterior shelf regions are relatively unaffected. Alcian blue staining combined with specific enzymic digestion was used to identify HA in sections of CHLR-treated shelves. With the aid of computer-assisted image subtraction the patterns of HA distribution across the tissue section were objectively identified. Anterior, posterior and presumptive soft palatal shelf regions were examined at gestational days 13·25, 13·5, 13·75 and 14·5. Acquisition of a normal pattern of HA distribution was delayed by about 24 h, as compared to untreated specimens in all three shelf regions. The posterior and soft regions, comprising the caudal two thirds of the shelf, also showed pronounced shape change. These regions only displayed normal curvature of the nasal surface when a normal pattern of HA distribution was attained. These results suggest that, for the caudal two thirds of the palatal shelf, normal shape and the ability to remodel are linked to the molecular configuration of HA and to a specific pattern of HA distribution.
Spreading of microinjected horseradish peroxidase to nondescendant cells in embryos of Patella (Mollusca, Gastropoda)
Authors: Kühtreiber Wiel M. , Serras Florenci , Biggelaar Jo A. M. van den
Published: April 2021

We have injected horseradish peroxidase (HRP) and fluorescein-isothiocyanate dextran (FD) into cells and into the blastocoelic cavity of Patella vulgata embryos, before and during the interval between 5th and 6th cleavage, in which the mesodermal stem cell is determined by means of interactions between the central 3D macromere and the contacting animal micromeres.

Intracellular injections of HRP at different stages showed that, whereas before this contact phase no spreading of label was observed, a clear intercellular transfer of HRP was found after the contact was established. Control experiments showed that it was HRP in its intact, high molecular weight form that was transferred in the living embryo.

Injections of HRP into the blastocoelic cavity gave essentially the same results. In these cases, the HRP was taken up by the cells from contact stage onwards. When FD was injected into the blastocoelic cavity, no uptake was observed, not even after prolonged presence of FD in it. However, when HRP and FD were mixed, both were taken up, starting at contact stage. Differences in labelling pattern of HRP, as compared with FD, and a shift of the FD fluorescence after uptake, suggest that receptor-mediated endocytosis is involved. The possible morphogenetic significance of the transfer mechanism is discussed.
Trans-regulatory functions in the Abdominal-B gene of the bithorax complex
Authors: Casanova Jordi , White Robert A. H.
Published: April 2021

We have investigated the functional organization of the Abdominal-B gene in the bithorax complex using the expression of the Ultrabithorax gene as an assay for Abdominal-B trans-regulatory functions. Using Polycomb mutants to relax the normal spatial control of Ultrabithorax expression, we have examined the effects of Abdominal-B mutations on the expression of Ultrabithorax protein products in parasegment 14. The results support the hypothesis that the Abdominal-B gene contains two trans-regulatory functions: the m element active in parasegments 10–13 and the r element acting exclusively in parasegment 14.
Chromosomal continuity in the abdominal region of the bithorax complex of Drosophila is not essential for its contribution to metameric identity
Authors: Tiong S. Y. K. , Whittle J. R. S. , Gribbin M. C.
Published: April 2021

We have examined the developmental consequences for larval and imaginal segmental cuticular structure of a chromosomal translocation involving a breakpoint in the abdominal region of the bithorax complex (BX-C). This complex makes an essential contribution to the development of metameric differences in part of the thorax and in all abdominal segments. The breakpoint is proximal to the most distal (iab-7) homeobox, and results in the translocation to the Y chromosome of the Ultrabithorax (Ubx) and abdominal-A (abd-A) domains. The genotype deficient for the distal part of the complex shows normal function for Ubx and abd-A but has a phenotype typical for severe Abd-B mutations. Conversely, the distal fragment retains a segment identity function which must represent a contribution from Abd-B in parasegments 13 and 14; the latter metamere is wild type, indicating that it does not require the contribution of Ubx or abd-A.

We also constructed a genotype comprising the proximal fragment of this translocation together with an overlapping distal fragment of the BX-C derived from Df(3R)Ubx109. It therefore contained all sequences of the BX-C though in the abdominal region the abd-A and Abd-B domains were not adjacent to each other in the chromosome. This genotype was phenotypically normal and demonstrates that DNA sequences in the abd-A and Abd-B regions do not require cis-arrangement for their activity.
Homoeobox gene Hox-1.5 expression in mouse embryos: earliest detection by in situ hybridization is during gastrulation
Authors: Gaunt Stephen J.
Published: April 2021

We showed earlier (Gaunt, Miller, Powell & Duboule, 1986) that the mouse homoeobox gene Hox-1.5 is expressed in posterior ectoderm and mesoderm of and -day embryos, and in the -day nervous system posterior to a discrete boundary within the hindbrain. In further in situ hybridization experiments, it is now shown that restriction of Hox-1.5 expression to the posterior regions of the embryo can be detected at stages of development between and days. During this period, the intensity of transcription in presomitic and somitic mesoderm declines rélative to that in the overlying neural ectoderm, and the transcription boundary within the presumptive hindbrain region sharpens. Hox-1.5 expression posterior to the hindbrain boundary is detected in the and -day embryo, but this is no longer found in newborn mice. Embryos of ages and days showed no evidence of Hox-1.5 transcripts. It is concluded that embryos undergoing gastrulation (at days) are the earliest stage at which Hox-1.5 transcripts can be detected by the in situ hybridization technique. In discussion, it is shown how this lies within the period of development during which tissues become determined along the anteroposterior axis of the mouse. Since there may be anterior-to-posterior variation in the time of determination along the body axis, it is suggested that homoeobox genes expressed more posteriorly, such as Hox-3 (Awgulewitsch et al. 1986), might start expression at times later in development.
Prenatal fate of parthenogenetic cells in mouse aggregation chimaeras
Authors: Nagy A. , Páldi A. , Dezso L. , Varga L. , Magyar A.
Published: April 2021

Parthenogenetically activated BCF1 and fertilized BALB/c embryos were aggregated to form chimaeras. The fate of the parthenogenetic component was followed in the conceptus during the second half of gestation. The results indicate an early strong selection against parthenogenetic cells in the extra-embryonal part, which is presumably complete by term, and a weaker selective process in the embryo. During early development, parthenogenetic cells have nearly normal developmental potency in the embryo, which allows their balanced contribution in the chimaeras on day 12. Later, this contribution declines significantly resulting in an unbalanced relation to the advantage of the fertilized counterpart. From the results, we suggest that gametic imprinting may play a role not only in the key steps of preimplantation and early postimplantation development, but later in cell and tissue differentiation.
Hierarchy of the genetic interactions that specify the anteroposterior segmentation pattern of the Drosophila embryo as monitored by caudal protein expression
Authors: Mlodzik Marek , Gehring Walter J.
Published: April 2021

The establishment of the body pattern of Drosophila along the anteroposterior axis requires the coordinated functions of at least three classes of genes. First, the maternally active ccordinate genes define the polarity of the embryo and act as primary determinants; second, the segmentation genes divide the developing embryo into the correct number of segments and third, the segments become specified by the homeotic selector genes. We have examined the effects of mutations in the genes of the first two classes on the spatial distribution of the protein product(s) of the caudal (cad) gene, which in wild type shows a graded distribution along the anteroposterior axis during the syncytial blastoderm stage, whereas its persistent zygotic expression is confined to the telson region (the posterior terminal structures). Mutations in maternal genes that specify the spatial coordinates of the egg and the future embryo change the gradient distribution of cad according to the alterations of the fate map which they produce. A second group of maternally expressed genes, the gap genes of the ‘grandchilless-knirps’ group, which are considered to represent posterior activities, do not have any effect on the cad gradient. The same is true for the zygotic segmentation genes that are active after fertilization. However, the same class of zygotic genes partly affects the zygotic cad expression in the telson. Therefore, the two phases of cad expression represent different levels within the genetic hierarchy. The cad protein gradient seems to form in response to the primary maternal determinants independent of the segmentation genes, whereas the latter influence zygotic cad expression in the telson region which corresponds to a homeotic selector gene function.
Directional cues for growing axons forming the retinotectal projection
Authors: Gierer Alfred
Published: April 2021

In the formation of projections that map one area of the nervous system onto another, guidance of axonal growth cones by directional cues encoded in target tissues is well established by observations on misrouted fibres, though other mechanisms contribute to the precision of connectivity patterns. General physical principles indicate that, if there is directional guidance of normally as well as misrouted axons, leading them toward their appropriate target positions, the inference for a role of graded distributions of molecules is a strong one. As explained in this paper, curving, meandering, branching and shifting connections are fully consistent with a crucial role of directional cues encoded by graded molecular distributions. A model is proposed according to which slight directional cues are strongly enhanced within the axonal growth cone; if the proximal part of the growth cone is activated indicating that the growth cone points in an entirely wrong direction, then a discontinuous directional change such as branching is elicited. Pathways are corrected in this way, and near the appropriate target position the terminal arbour is formed because from there all routes point towards less optimal positions, leading to multiple branching.
Developmental regulation of two microtubule-associated proteins (MAP2 and MAP5) in the embryonic avian retina
Authors: Tucker R. P. , Matus A. I.
Published: April 2021

Previous studies with the mammalian brain have shown that the expression of a number of neuronal microtubule-associated proteins (MAPs) is developmentally regulated. For example, the low-molecular-weight form of MAP2 (MAP2c) is abundant in neonatal rat brains and is less abundant in adults. Similarly, MAP5 levels decrease during postnatal development. Using monoclonal antibodies, we have followed the time of first appearance, cellular distribution, and molecular form of MAP2 and MAP5 during the morphogenesis of the quail retina. MAP2 first appears in ganglion cell bodies and in the axons of the optic fibre layer (OFL) at embryonic day 4 (E4). Anti-MAP2 staining remains restricted to these sites until E10, when staining appears in the inner plexi-form layer (IPL). At E14, one day before hatching, anti-MAP2 staining is found in three broad laminae in the IPL, as well as in photosensitive cells. MAP5 is present in ganglion cell axons from the onset of neurite elongation at E3 and is limited to the OFL until E10. The intensity of anti-MAP5 staining in the OFL and optic nerve decreases after E7, which corresponds with a decrease in the number of actively growing ganglion cell axons. By E14, anti-MAP5 stains five layers in the IPL that correspond with layers of amacrine cell process arborizations. Western blots of E10 brain microtubule proteins show that MAPI is represented by both a 260×103Mr protein and a 60–65 × 103Mr protein; the latter is much more abundant. Anti-MAP5 recognizes a 320×103Mr brain microtubule protein in both the quail and the rat. We conclude that the cellular distribution, developmental regulation and molecular forms of MAP2 and MAP5 are similar in the rat and quail, suggesting that these molecules have conserved and hence fundamental roles in the growth and differentiation of neuronal processes.
Instability of the anteroposterior axis in spontaneous double abdomen (sda), a genetic variant of Chironomus samoensis (Diptera, Chironomidae)
Authors: Kuhn Kristen L. , Percy Jean , Laurel Myrtha , Kalthoff Klaus
Published: April 2021

We have isolated a laboratory strain of Chironomus samoensis in which determination of the anteroposterior egg polarity is disturbed. Most conspicuous is the spontaneous formation of ‘double abdomen’ embryos where head and thorax are replaced by a mirror image of the abdomen. Such double abdomens are found in about half of the egg clusters in this strain, which we call the spontaneous double abdomen (sda) strain as opposed to the normal (N) strain. Also observed in the sda strain, although less frequently, are ‘double cephalon’ embryos showing a mirrorimage duplication of cephalic segments in the absence of thorax and abdomen. Moreover, embryos from the sda strain tend to form cells at the anterior pole resembling the pole cells at the posterior pole. Reciprocal crossings between the sda and the N strain indicate that the sda trait is inherited maternally. Spontaneous double abdomen formation is correlated with signs of disturbed egg architecture, including extruded yolk and detached cells. Double cephalons can also be generated by centrifuging embryos from the N strain, whereas centrifugation of sda embryos produces mostly double abdomens. Double abdomen formation can be induced experimentally by anterior u.v. irradiation of embryos from either strain. The sda trait and u.v. irradiation act in a synergistic fashion. The data suggest that the sda trait may be caused by one or more genomic mutations interfering indirectly with the activity of anterior determinants, i.e. cytoplasmic RNP particles necessary for the development of anterior segments. The sda defects may be ascribed to alterations in cytoskeletal components involved in anchoring anterior determinants and segregating them into anterior blastoderm cells.
Coding sequence and expression of the homeobox gene Hox 1.3
Authors: Fibi Mathias , Zink Barbara , Kessel Michael , Colberg-Poley Anamaris M. , Labeit Siegfried , Lehrach Hans , Gruss Peter
Published: April 2021

We have characterized Hox 1.3 (previously described as m2), a murine homeobox-containing gene, which is a member of the Hox 1 cluster located on chromosome 6. A cloned cDNA was isolated from an Okayama-Berg library generated from the chemically transformed cell line MB66 MCA ACL6. The protein sequence of 270 amino acids was deduced from the nucleotide sequence of an open reading frame containing the homeobox. The open reading frame is interrupted at the genomic level by a 960 bp intron and is organized in two exons. The Hox 1.3 protein was found to contain extensive sequence homology with the murine homeodomain protein Hox 2.1, which is encoded on chromosome 11. There are two homologous regions in the first exon, i.e. a hexapeptide conserved in many homeobox-containing genes and the N-terminal domain, which was found to be homologous only to Hox 2.1. Furthermore, in exon 2 the homologies of the homeodomain regions are extended up to the carboxy terminus of Hox 1.3 and Hox 2.1.

During prenatal murine development, maximal expression of Hox 1.3 is observed in 12-day embryonic tissue. The two transcripts carrying the Hox 1.3 homeobox are 1·9 kb and about 4 kb in length. An abundant Hox 1.3-specific 1·9 kb RNA is also found in F9 cells which were induced for parietal endoderm differentiation, whereas F9 teratocarcinoma stem cells do not stably express this specific RNA. Induction of the transcript occurs immediately after retinoic acid/ cAMP treatment and the RNA level remains high for 5 days. Thus, the kinetics are different from the previously described homeobox transcripts Hox 1.1 and Hox 3.1. Interestingly, by analogy to the F9 cell system a negative correlation between transformation and Hox 1.3 expression is observed in 3T3 fibroblasts also. Untransformed 3T3 cells carry abundant 1·9 kb Hox 1.3 RNA, whereas the methylcholanthrene-transformed MB66 and LTK—cells or 3T3 cells transformed by the oncogenes src, fos or SV40 T antigen express only low levels.
Axons regulate Schwann cell expression of the major myelin and NGF receptor genes
Authors: Lemke Greg , Chao Moses
Published: April 2021

The elaboration of myelin by Schwann cells is triggered by contact with appropriate peripheral axons. Among the most prominent features of this interaction is the activation and high-level expression of the genes encoding the major myelin proteins P0 and Myelin Basic Protein (MBP). Although the initial induction of these genes is thought to be dependent upon contact with axons, neither the inductive signal of the axon nor the receptor and associated second messenger system of the Schwann cell that transduces this signal has been identified. In this report, we demonstrate that expression of the P0 and MBP genes in rapidly myelinating Schwann cells is sharply reduced upon withdrawal of axons, but that this expression can be substantially restored by agents that raise the intracellular concentration of cyclic AMP. We further show that Schwann cell expression of a third gene, i.e. that encoding the Nerve Growth Factor receptor, is strongly activated by the withdrawal of axons, and that this activation is largely independent of cAMP.
The positional effect of presumptive primordial germ cells (pPGCs) on their differentiation into PGCs in Xenopus
Authors: Ikenishi Kohji , Tsuzaki Yoshinari
Published: April 2021

To determine whether the location of ‘germ plasm’-bearing cells [presumptive primordial germ cells (pPGCs)] is crucial for their differentiation into PGCs in Xenopus, [3H]thymidine-labelled pPGCs were implanted into the anterior or posterior halves of the endoderm in unlabelted host neurulae. Labelled PGCs in the genital ridges of experimental tadpoles were investigated by autoradiography.

When the labelled pPGCs were implanted into posterior halves of the endoderm where host pPGCs are situated, 65 and 77 % of the experimental tadpoles (designated as p-tadpoles) had the labelled PGCs in series 1 and II, respectively. When implanted into the anterior halves, 20 and 27 % of the experimental tadpoles (a-tadpoles) had the labelled PGCs in series I and II, respectively. In p-tadpoles, the average numbers of labelled PGCs per tadpole were 8·7 in series I and 10 in series II, whereas they were 2· 0 in a-tadpoies of both series. Both the proportion and the average number in p-tadpoles of both series were significantly different from those in a-tadpoles. In both series, labelled PGCs in p-tadpoles were found to be distributed throughout the genital ridges while those in a-tadpoles were localized only in the anterior part of the ridges. These facts indicate that the location of pPGCs in the endoderm affects their successful migration into the genital ridges, and that not only the presence of the germ plasm but also the proper location in endoderm are prerequisites to PGC differentiation of the germ line cells.
Developmental changes of the proliferative response of mouse epidermal melanocytes to skin wounding
Authors: Hirobe Tomohisa
Published: April 2021

A cut was made on the middorsal skin of mice of various ages of strain C57BL/10J using fine iridectomy scissors. Specimens from the wounded skins were fixed at various days after wounding and were subjected to the dopa reaction and to the combined dopa-premelanin reaction. When the dorsal skins of 1·5-day-old mice were wounded, the melanocyte population positive to the dopa reaction as well as the melanoblast-melanocyte population positive to the combined dopa-premelanin reaction increased dramatically in the epidermis adjacent to a skin wound. Pigment-producing melanocytes in mitosis were frequently found in the vicinity of a wound immediately after wounding. When the dorsal skins of 4·5-day-old mice were wounded, the increase in the melanocyte and melanoblast-melanocyte populations was smaller than that of 1·5-day-old mice. The increase in number of pigment-producing melanocytes in mitosis was reduced and delayed as compared to 1·5-day-old mice. When the dorsal skins of 8·5-, 20·5-, and 60·5-day-old mice were wounded, the increase in the melanocyte and melanoblast-melanocyte populations was much smaller than the newborn mice. Moreover, pigmentproducing melanocytes in mitosis were never found. These results indicate that the proliferative response of mouse epidermal melanocytes to skin wounding becomes delayed and diminished with development.
The influence of cell contact on the division of mouse 8-cell blastomeres
Authors: Pickering Susan J. , Maro Bernard , Johnson Martin H. , Skepper Jeremy N.
Published: April 2021

The pattern of division of polarized 8-cell blastomeres with respect to the axis of cell polarity has been compared (i) for cells dividing alone with cells dividing in pairs, and (ii) for early and late dividing cells within a pair. Cell interactions do not seem to influence significantly the overall pattern of division within the population. The only significant difference found was that the second dividing cell in a pair tended to divide in the same way as its earlier dividing companion slightly more frequently than expected. These results suggest that cell interactions immediately prior to and during division do not influence strongly the orientation and position of the division plane. In contrast, interactions between the cells within an intact early 8-cell embryo, which is subsequently disaggregated to singletons or pairs, do influence the type of progeny generated at division to the 16-cell stage, and seem to do so via an effect on the size of the microvillous region generated at the cell apex.
Patterning of connective tissues in the head: discussion report
Authors: Hall Brian K.
Published: April 2021

The three papers presented by Noden, Thorogood and Lumsden in this session encompassed the connective tissues as broadly defined, i.e. soft (fibrous) connective tissue, cartilage, bone, muscle and the dental tissues, enamel and dentine, and utilized a variety of experimental techniques on both avian and mammalian embryos to explore specificity and patterning of the vertebrate head. Whether similar developmental processes pattern homologous structures in different Vertebrate classes (Amphibia, Aves, Mammalia) was discussed with reference to patterning of the cranial musculature, chondrocranium and dental tissues. A number of challenging ideas emerged during this session. Does the premigratory neural crest consist of a homogenous population of totipotent cells or of subpopulations of bi- or tripotential cells? Is fundamental patterning of the head an early embryonic event, perhaps specified during primary embryonic induction or the consequence of neuroepithelial folding, brain growth, inductive interactions and/or spatially and temporally distributed extracellular matrix products? Can the fact that mesoderm and angioblasts do not display distinctive patterning that relates to their particular embryologic origins be extrapolated to patterning in general? How does the documentation of an ondontogenic trunk neural crest in mammals affect our theories of how patterning mechanisms arose or were modified during vertebrate evolution?