Pluripotency of a founding field: rebranding developmental biology

The field of developmental biology has declined in prominence in recent decades, with off-shoots from the field becoming more fashionable and highly funded. This has created inequity in discovery and opportunity, partly due to the perception that the field is antiquated or not cutting edge. A 'think tank' of scientists from multiple developmental biology-related disciplines came together to define specific challenges in the field that may have inhibited innovation, and to provide tangible solutions to some of the issues facing developmental biology. The community suggestions include a call to the community to help 'rebrand' the field, alongside proposals for additional funding apparatuses, frameworks for interdisciplinary innovative collaborations, pedagogical access, improved science communication, increased diversity and inclusion, and equity of resources to provide maximal impact to the community.

Insights from electronic health record data to improve mental health service delivery during the COVID-19 pandemic

Background

Remote consultation technology has been rapidly adopted due to the COVID-19 pandemic. However, some healthcare settings have faced barriers in implementation. We present a study to investigate changes in rates of remote consultation during the pandemic using a large electronic health record (EHR) dataset.

Methods

The Clinical Record Interactive Search tool (CRIS) was used to examine de-identified EHR data of people receiving mental healthcare in South London, UK. Data from around 37,500 patients were analysed for each week from 7th January 2019 and 20th September 2020 using linear regression and locally estimated scatterplot smoothing (LOESS) to investigate changes in the number of clinical contacts (in-person, remote or non-attended) with mental healthcare professionals and prescribing of antipsychotics and mood stabilisers. The data are presented in an interactive dashboard: http://rpatel.co.uk/TelepsychiatryDashboard.

Results

The frequency of in-person contacts was substantially reduced following the onset of the pandemic (β coefficient: -5829.6 contacts, 95% CI -6919.5 to -4739.6, p<0.001), while the frequency of remote contacts increased significantly (β coefficient: 3338.5 contacts, 95% CI 3074.4 to 3602.7, p<0.001). Rates of remote consultation were lower in older adults than in working age adults, children and adolescents. Despite the increase in remote contact, antipsychotic and mood stabiliser prescribing remained at similar levels.

Conclusions

The COVID-19 pandemic has been associated with a marked increase in remote consultation, particularly among younger patients. However, there was no evidence that this has led to changes in prescribing. Further work is needed to support older patients in accessing remote mental healthcare.

Disclosure

All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: RS has received funding from Janssen, GSK and Takeda outside the submitted work. RP has received funding from Janssen, Induction Healthcare and H

Dimerization quality control ensures neuronal development and survival

Aberrant complex formation by recurrent interaction modules, such as BTB domains, leucine zippers, or coiled coils, can disrupt signal transduction, yet whether cells detect and eliminate complexes of irregular composition is unknown. By searching for regulators of the BTB family, we discovered a quality control pathway that ensures functional dimerization [dimerization quality control (DQC)]. Key to this network is the E3 ligase SCF^FBXL17, which selectively binds and ubiquitylates BTB dimers of aberrant composition to trigger their clearance by proteasomal degradation. Underscoring the physiological importance of DQC, SCF^FBXL17 is required for the differentiation, function, and survival of neural crest and neuronal cells. We conclude that metazoan organisms actively monitor BTB dimerization, and we predict that distinct E3 ligases similarly control complex formation by other recurrent domains.

Sheep from low-methane-yield selection lines created on alfalfa pellets also have lower methane yield under pastoral farming conditions

Selection lines of sheep with low and high CH yield (g/kg DMI; CH/DMI) are being developed on the basis of feeding pelleted alfalfa hay at 2.0 times maintenance ME requirements in respiration chambers, but their divergence under predominant grazing conditions, as in New Zealand, is not known. The objectives of this study were to determine CH emissions and rumen fermentation characteristics in sheep from low and high CH/DMI selection lines while grazing pasture. Two grazing experiments were conducted with 42 selection line ewes in March 2013 (Exp. 1) and 98 selection line progeny ewe hoggets in October/November 2014 (Exp. 2), with CH emissions estimated by the SF tracer technique and DMI estimated by titanium oxide in combination with natural long-chain -alkanes. Total daily CH production (g/d) was similar between high and low CH/DMI selection line sheep in Exp. 1 and lower for low CH/DMI progeny compared with high CH/DMI progeny in Exp. 2 ( < 0.05). The CH/DMI tended to be 20% lower for low CH/DMI line sheep compared with high CH/DMI selection line sheep in Exp. 1 ( < 0.10) and was 15% lower for the low CH/DMI line in Exp. 2 ( < 0.01). Total VFA concentration and concentrations (m) of acetate, butyrate, and isobutyrate plus isovalerate were lower ( < 0.05) for low CH/DMI line sheep compared with high CH/DMI selection line sheep in both experiments. The current study indicates that differences in CH/DMI and VFA concentrations in selection line sheep, previously established on alfalfa pellets, are also present to a similar magnitude when grazing pasture.

Roles of Wnt pathway genes wls, wnt9a, wnt5b, frzb and gpc4 in regulating convergent-extension during zebrafish palate morphogenesis

The Wnt signaling pathway is crucial for tissue morphogenesis, participating in cellular behavior changes, notably during the process of convergent-extension. Interactions between Wnt-secreting and receiving cells during convergent-extension remain elusive. We investigated the role and genetic interactions of Wnt ligands and their trafficking factors Wls, Gpc4 and Frzb in the context of palate morphogenesis in zebrafish. We describe that the chaperon Wls and its ligands Wnt9a and Wnt5b are expressed in the ectoderm, whereas juxtaposed chondrocytes express Frzb and Gpc4. Using wls, gpc4, frzb, wnt9a and wnt5b mutants, we genetically dissected the Wnt signals operating between secreting ectoderm and receiving chondrocytes. Our analysis delineates that non-canonical Wnt signaling is required for cell intercalation, and that wnt5b and wnt9a are required for palate extension in the anteroposterior and transverse axes, respectively.

The POU-er of gene nomenclature

The pluripotency factor POU5F1 (OCT4) is well known as a key regulator of stem cell fate. Homologues of POU5F1 exist throughout vertebrates, but the evolutionary and functional relationships between the various family members have been unclear. The level to which function has been conserved within this family provides insight into the evolution of early embryonic potency. Here, we seek to clarify the relationship between POU5F1 homologues in the vertebrate lineage, both phylogenetically and functionally. We resolve the confusion over the identity of the zebrafish gene, which was originally named pou2, then changed to pou5f1 and again, more recently, to pou5f3. We argue that the use of correct nomenclature is crucial when discussing the degree to which the networks regulating early embryonic differentiation are conserved.

Abstract P6-07-13: Local relapse and survival

Aim: Local recurrence may precede distant relapse and death. Many factors which predict local recurrence also predict death. Few studies have investigated the contribution of local recurrence to mortality independent of prior prognostic factors such as nodal status. We wished to estimate the extent to which overall survival is affected specifically by local recurrence.

Methods: 114 of of 2945 patients aged 19 to 94 years (mean 58.3) who had either mastectomy or breast conservation for breast cancer between 1991 and 2011 subsequently suffered an ipsilateral local recurrence. We matched, with one exception (due to extreme young age), each patient who had a local recurrence with 2 controls matched for calendar year of presentation, age, nodal status, grade, and tumour size. A Cox regression analysis of survival from the first therapeutic operation was done on the case matched subset with local recurrence coded dichotomously and age coded continuously as the absolute deviation from the population mean (as both young and old age affect survival adversely) as predictors. To confirm independence of the effect of local recurrence on the hazard of death a further Cox regression analysis of survival as above was done for the whole series with local recurrence, Grade 3, &gt;3 nodes involved, tumour diameter &gt;40mm, coded dichotomously, and age coded as above as independent variables.

Results: The results of the analyses are given in the table below.

A rare cause of small bowel infarction

We report a rare case of small bowel infarction due to superior mesenteric artery occlusion secondary to cardiac tumour embolism. To our knowledge, this has not been previously reported in the literature. This case highlights a rare case and reviews current knowledge on the subject.

A study of psychiatrists' concepts of mental illness

BACKGROUND

There are multiple models of mental illness that inform professional and lay understanding. Few studies have formally investigated psychiatrists' attitudes. We aimed to measure how a group of trainee psychiatrists understand familiar mental illnesses in terms of propositions drawn from different models.

METHOD

We used a questionnaire study of a sample of trainees from South London and Maudsley National Health Service (NHS) Foundation Trust designed to assess attitudes across eight models of mental illness (e.g. biological, psychodynamic) and four psychiatric disorders. Methods for analysing repeated measures and a principal components analysis (PCA) were used.

RESULTS

No one model was endorsed by all respondents. Model endorsement varied with disorder. Attitudes to schizophrenia were expressed with the greatest conviction across models. Overall, the 'biological' model was the most strongly endorsed. The first three components of the PCA (interpreted as dimensions around which psychiatrists, as a group, understand mental illness) accounted for 56% of the variance. Each main component was classified in terms of its distinctive combination of statements from different models: PC1 33% biological versus non-biological; PC2 12% 'eclectic' (combining biological, behavioural, cognitive and spiritual models); and PC3 10% psychodynamic versus sociological.

CONCLUSIONS

Trainee psychiatrists are most committed to the biological model for schizophrenia, but in general are not exclusively committed to any one model. As a group, they organize their attitudes towards mental illness in terms of a biological/non-biological contrast, an 'eclectic' view and a psychodynamic/sociological contrast. Better understanding of how professional group membership influences attitudes may facilitate better multidisciplinary working.

Induction into the Hall of Fame: tracing the lineage of Spemann's organizer

The grafting experiments of Spemann and Mangold have been a textbook classic for years, but as with many conclusions from experimental embryology, the idea that the dorsal lip of the blastopore ;organized' the early patterning of the embryo has sometimes come under question. In their 1983 paper in JEEM, Smith and Slack extended these classical experiments in newts to the now-standard amphibian model Xenopus laevis. By using injected lineage tracers, they distinguished the fates of graft and host, and showed unambiguously that the organizer is responsible for neural induction and that it dorsalizes the mesoderm.

Evading the annotation bottleneck: using sequence similarity to search non-sequence gene data

Background

Non-sequence gene data (images, literature, etc.) can be found in many different public databases. Access to these data is mostly by text based methods using gene names; however, gene annotation is neither complete, nor fully systematic between organisms, and is also not generally stable over time. This provides some challenges for text based access, especially for cross-species searches. We propose a method for non-sequence data retrieval based on sequence similarity, which removes dependence on annotation and text searches. This work was motivated by the need to provide better access to large numbers of in situ images, and the observation that such image data were usually associated with a specific gene sequence. Sequence similarity searches are found in existing gene oriented databases, but mostly give indirect access to non-sequence data via navigational links.

Results

Three applications were built to explore the proposed method: accessing image data, literature and gene names. Searches are initiated with the sequence of the user's gene of interest, which is searched against a database of sequences associated with the target data. The matching (non-sequence) target data are returned directly to the user's browser, organised by sequence similarity. The method worked well for the intended application in image data management. Comparison with text based searches of the image data set showed the accuracy of the method. Applied to literature searches it facilitated retrieval of mostly high relevance references. Applied to gene name data it provided a useful analysis of name variation of related genes within and between species.

Conclusion

This method makes a powerful and useful addition to existing methods for searching gene data based on text retrieval or curated gene lists. In particular the method facilitates cross-species comparisons, and enables the handling of novel or otherwise un-annotated genes. Applications using the method are quick and easy to build, and the data require little maintenance. This approach largely circumvents the need for annotation, which can be a major obstacle to the development of genomic scale data resources.

The road to licensure of a DNA vaccine

The licensure of three DNA vaccines for animal health applications has provided renewed interest in the broader potential of this technology. At the very least, this will spur efforts to understand the reasons behind these successes and whether this information can be used to enable DNA vaccines for humans. This review maps the pathway to the licensure of the DNA vaccine against infectious hematopoietic necrosis virus in fish, and discusses the implications of this on the development of human DNA vaccines.

Noggin suppression enhances in vitro osteogenesis and accelerates in vivo bone formation

Several investigations have demonstrated a precise balance to exist between bone morphogenetic protein (BMP) agonists and antagonists, dictating BMP signaling and osteogenesis. We report a novel approach to manipulate BMP activity through a down-regulation of the potent BMP antagonist Noggin, and examined the effects on the bone forming capacity of osteoblasts. Reduction of noggin enhanced BMP signaling and in vitro osteoblast bone formation, as demonstrated by both gene expression profiles and histological staining. The effects of noggin suppression on in vivo bone formation were also investigated using critical-sized calvarial defects in mice repaired with noggin-suppressed osteoblasts. Radiographic and histological analyses revealed significantly more bone regeneration at 2 and 4 weeks post-injury. These findings strongly support the concept of enhanced osteogenesis through a down-regulation in Noggin and suggest a novel approach to clinically accelerate bone formation, potentially allowing for earlier mobilization of patients following skeletal injury or surgical resection.

Noncytopathic bovine viral diarrhea virus can persist in testicular tissue after vaccination of peri-pubertal bulls but prevents subsequent infection

The objectives of this research were to evaluate the risk of prolonged testicular infection as a consequence of vaccination of peri-pubertal bulls with a modified-live, noncytopathic strain of BVDV and to assess vaccine efficacy in preventing prolonged testicular infections after a subsequent acute infection. Seronegative, peri-pubertal bulls were vaccinated subcutaneously with an approximate minimum immunizing dose or a 10x standard dose of modified-live, noncytopathic BVDV or were maintained as unvaccinated controls. Forty-nine days after vaccination, all bulls were intranasally inoculated with a noncytopathic field strain of BVDV. Semen and testicular biopsies collected after vaccination and challenge were assayed for BVDV using virus isolation, reverse transcription-nested PCR, or immunohistochemistry and the identity of viral strains was determined by nucleotide sequencing of PCR products. The vaccine strain of BVDV was detected in testicular tissue of vaccinated bulls as long as 134 days after immunization. Prolonged testicular infections with the challenge strain were detected only in unvaccinated bulls as long as 85 days after challenge. Whereas vaccination caused prolonged testicular infection in some bulls, it did prevent subsequent infection of testicular tissue with the challenge strain. This research demonstrates that subcutaneous vaccination of naïve, peri-pubertal bulls with a noncytopathic, modified-live strain of BVDV can result in prolonged viral replication within testicular tissue. The risk for these prolonged testicular infections to cause venereal transmission of BVDV or subfertility is likely to be low but requires further investigation.

Protection against fetal infection with either bovine viral diarrhea virus type 1 or type 2 using a noncytopathic type 1 modified-live virus vaccine

Two bovine viral diarrhea virus (BVDV) fetal protection studies were done using a monovalent noncytopathic (NCP) BVDV vaccine containing type 1 BVDV. In study 1, thirty-two fetuses (23 vaccinates and nine controls) were recovered following fetal challenge with the type 1a BJ strain. Twenty of twenty-three fetuses from the vaccinates were negative for BVDV type 1 while all of the controls (nine of nine) were infected. In study 2, twenty-two animals (14 vaccinates and eight controls) were challenged with the type 2 PA131 strain. Thirteen of the fourteen fetuses from the vaccinates were negative for BVDV type 2 while all of the nonvaccinated controls (eight of eight) were infected. These results indicate the efficacy of a monovalent NCP BVDV vaccine in providing excellent protection against either BVDV type 1 or 2 fetal infection.

Msx1 and Pax3 cooperate to mediate FGF8 and WNT signals during Xenopus neural crest induction

FGF, WNT, and BMP signaling promote neural crest formation at the neural plate boundary in vertebrate embryos. To understand how these signals are integrated, we have analyzed the role of the transcription factors Msx1 and Pax3. Using a combination of overexpression and morpholino-mediated knockdown strategies in Xenopus, we show that Msx1 and Pax3 are both required for neural crest formation, display overlapping but nonidentical activities, and that Pax3 acts downstream of Msx1. In neuralized ectoderm, Msx1 is sufficient to induce multiple early neural crest genes. Msx1 induces Pax3 and ZicR1 cell autonomously, in turn, Pax3 combined with ZicR1 activates Slug in a WNT-dependent manner. Upstream of this, WNTs initiate Slug induction through Pax3 activity, whereas FGF8 induces neural crest through both Msx1 and Pax3 activities. Thus, WNT and FGF8 signals act in parallel at the neural border and converge on Pax3 activity during neural crest induction.

Bipolar electrocoagulation for clipless division of left renal vein branches during laparoscopic living donor nephrectomy

We present our experience of using the bipolar electrocautery for division of the left renal vein branches in laparoscopic right living donor nephrectomy. This has been performed in 160 cases with no complications related to the technique. The absence of laparoscopic clips allows easier and safer placement of the endostaple.

Expression of Sox3 throughout the developing central nervous system is dependent on the combined action of discrete, evolutionarily conserved regulatory elements

SOX3 is one of the earliest neural markers in vertebrates and is thought to play a role in specifying neuronal fate. To investigate the regulation of Sox3 expression we identified cis-regulatory regions in the Sox3 promoter that direct tissue-specific heterologous marker gene expression in transgenic mice. Our results show that an 8.3 kb fragment, comprising 3 kb upstream and 3 kb downstream of the Sox3 transcriptional unit, is sufficient in a lacZ reporter construct to reproduce most aspects of Sox3 expression during CNS development from headfold to midgestation stages. The apparently uniform expression of Sox3 in the neural tube depends, however, on the combined action of distinct regulatory modules within this 8.3 kb region. Each of these gives expression in a subdomain of the complete expression pattern. These are restricted along both the rostral-caudal and dorso-ventral axes and can be quite specific, one element giving expression largely confined to V2 interneuron precursors. We also find that at least some of the regulatory sequences are able to drive expression of the transgene in the CNS Xenopus laevis embryos in a manner that reflects the endogenous Sox3 expression pattern. These results imply that the underlying mechanism regulating early CNS patterning is conserved, despite several substantial differences in neurogenesis between mammals and amphibians.

Hand-assisted laparoscopic donor nephrectomy minimizes warm ischemia

OBJECTIVES

Traditional open donor nephrectomy is associated with good donor outcomes and excellent allograft function. Laparoscopic donor nephrectomy may accomplish these same goals with less morbidity. We report our initial experience with hand-assisted laparoscopic living donor nephrectomy using a commercially available hand-assist device.

METHODS

Donor and allograft outcomes for the first 30 patients undergoing hand-assisted laparoscopic live donor nephrectomy in our institution were prospectively analyzed.

RESULTS

Hand-assisted laparoscopic donor nephrectomy was successfully completed in 29 (97%) of 30 donors. Organ dissection was carried out purely laparoscopically. Vessel division and allograft extraction were performed using a hand-assisted technique. The average operative time was 275 minutes (range 193 to 360), with an estimated blood loss of 99 mL (range 50 to 300). Pneumoperitoneum was consistently maintained during the hand-assisted portion of the procedure. The mean warm ischemic time was 72.5 seconds (range 30 to 165). On average, the regular diet was resumed after 2.2 days (range 1 to 3), and patients were discharged home 3.4 days (range 2 to 5) after surgery. Eight minor complications occurred in the donor group. Immediate graft function occurred in all 30 cases. No ureteral complications occurred. The recipient creatinine levels ranged from 0.6 to 2.4 mg/dL at an average follow-up of 11.5 months (range 1 to 23).

CONCLUSIONS

Laparoscopic donor nephrectomy is technically feasible and can be performed with minimal morbidity. Hand-assisted kidney extraction may help to facilitate immediate allograft function by minimizing the warm ischemic time.

The relationship between the occurrence of undifferentiated bovine respiratory disease and titer changes to Haemophilus somnus and Mannheimia haemolytica at 3 Ontario feedlots

The association between exposure to Haemophilus somnus and Mannheimia haemolytica (formerly Pasteurella haemolytica) and the risk of undifferentiated bovine respiratory disease (UBRD) was investigated using serological evidence of exposure coupled with a factorial design vaccine field trial. Measures of previous exposure (titer at arrival) and current exposure (titer increase in the study period) to these agents were used. The vaccine field trial involved systematic allocation of animals into groups that received either a M. haemolytica vaccine, an H. somnus vaccine, a combined M. haemolytica and H. somnus vaccine, and an unvaccinated control group. Serum was collected from the 852 animals enrolled to determine titers to H. somnus, M. haemolytica, bovine coronavirus and bovine viral diarrhea virus. Vaccination with H. somnus in combination with M. haemolytica and with M. haemolytica alone reduced the risk of UBRD. The odds ratio for vaccination with H. somnus alone and UBRD risk suggested some sparing effect, but the 95% confidence limits included unity. There was no association between serological evidence of concurrent exposure to M. haemolytica and UBRD occurrence. There was an association between titer change to H. somnus and UBRD risk. However, the association changed with time of BRD treatment; animals diagnosed and treated for UBRD on or after day 10 showed little evidence of exposure to H. somnus, despite evidence of natural H. somnus exposure in the unvaccinated group. The association between titer change to H. somnus and UBRD occurrence seen in this study may be a consequence of prolonged exposure to antibiotics, rather than a causal association.

The relationship between the occurrence of undifferentiated bovine respiratory disease and titer changes to bovine coronavirus and bovine viral diarrhea virus in 3 Ontario feedlots

Serological evidence of previous viral exposure (titer at arrival) and current viral exposure (titer increase) during a 28-day study period, was used to determine if bovine coronavirus (BCV) or bovine viral diarrhea virus (BVDV) was associated with the occurrence of undifferentiated bovine respiratory disease (UBRD) in feedlot calves. Neutralizing antibody titers to BCV and BVDV were determined for 852 animals from 3 Ontario feedlots. Calves at 2 of the 3 feedlots (n = 753) received a modified live 4-way viral vaccine containing BVDV. On arrival at the feedlots, 90% of animals were seropositive for BCV, while 39% of animals were seropositive for BVDV. This evidence of previous exposure to both viruses was associated with reduced subsequent UBRD risk. Evidence of exposure to BCV during the study period was common, as 50% of animals showed a 16-fold or greater titer increase; however, treatment for UBRD was not associated with titer change. Although the majority of animals were vaccinated for BVDV at arrival, within a feedlot, animals treated for UBRD had larger titer increases to BVDV than non-treated animals. Based on our findings we infer that BCV was not causally related to UBRD occurrence, however consistent with other literature, BVDV may be causally related to UBRD occurrence.

Effects of immunization against GnRH, melengestrol acetate, and a trenbolene acetate/estradiol implant on growth and carcass characteristics of beef heifers

A 2 x 3 factorial experiment was conducted to determine the effects of an implant (trenbolene acetate/estradiol or no implant) and method of estrus suppression (immunization against GnRH, melengestrol acetate, or no suppression) on growth performance and carcass characteristics of heifers fed for slaughter. At the start of a 21-d feed adaption phase, crossbred beef heifers (n = 144, 390+/-2.8 kg) were given their first dose of an anti-GnRH vaccine or started on melengestrol acetate (MGA). Thereafter, heifers were fed a high-concentrate diet (78% barley grain) for 84 d (Days 0 to 83), received implants on Day 0, a second vaccination on Day 21, and were slaughtered on Days 84 or 85. Implanting increased average daily gain (1.72 vs 1.50 kg/d, P < 0.01), feed efficiency (6.02 vs 6.75 kg dry matter intake/kg gain, P < 0.01), preslaughter weight (532 vs 513 kg, P < 0.01), carcass weight (301 vs 289 kg, P < 0.01), and ribeye area (88.6 vs 85.9 cm2, P < 0.05), but had no affect (P > 0.05) on dry matter intake, grade fat thickness, marbling score, or lean yield. Compared to heifers fed MGA, those immunized against GnRH had a greater ribeye area (90.0 vs 84.6 cm2) and lean yield (63 vs 61%), and had thinner grade fat (7.5 vs 8.6 mm; P < 0.05 for each). Furthermore, immunized heifers had lower (P < 0.001) plasma progesterone concentrations than control heifers on Days 42, 63 and 83. Heifers fed MGA had less estrus mounting activity (P < 0.05) and lower plasma progesterone concentrations (P < 0.001) than the remaining heifers. Method of estrus suppression did not affect (P > 0.05) preslaughter weight, average daily gain, dry matter intake, feed efficiency, carcass weight, or marbling score. In conclusion, implanting significantly increased growth performance and preslaughter and carcass weights. Compared to heifers fed MGA, immunization against GnRH significantly increased ribeye area and lean yield, and reduced grade fat thickness

The effects of active immunization against gnRH on testicular development, feedlot performance, and carcass characteristics of beef bulls

The objective was to determine the effects of a recombinant fusion protein anti-GnRH vaccine on testicular development, feedlot performance, and carcass quality of beef bulls. Crossbred beef bulls (n = 58, average weight 306 kg, 9 mo of age), were randomly allocated to two groups and received either an anti-GnRH vaccine (GnRH) or placebo (Control) by intramuscular injection on d 0, 56, and 112. There were group effects (P < 0.01; as a percentage of Control) on testicular weight (53%), daily sperm production (40%), and epididymal sperm reserves (16%). There were group x time interactions (P < 0.0001) for scrotal circumference and serum testosterone concentrations; at slaughter, bulls in the GnRH group had a smaller (P < 0.05) scrotal circumference (28.3 vs 33.9 cm) and lower (P < 0.05) serum testosterone concentrations (2.2 vs 8.6 ng/mL) than those in the Control group. Average daily gain, feed intake, and feed efficiency were not different between treatments during the backgrounding phase (d 0 to 84). During the finishing phase (d 98 to 182), ADG was greater (P < 0.05) for bulls in the Control group (1.69 vs 1.42 kg/d), as was carcass weight (6.9%; P < 0.01). However, GnRH bulls had numerically better feed efficiency (6.12 vs 7.08 kg DMI/kg gain; P < 0.23) and shear force values for ribeye that were 16% lower (P < 0.14) than Control bulls, warranting further investigation. Vaccinating bulls against GnRH suppressed testicular function, with growth and carcass characteristics similar to that expected with steers.

Neural induction

Development of neural fates from ectoderm is accompanied by the blockage of BMP signals at both protein and mRNA levels. Recent work has employed zebrafish, chick and mouse in addition to amphibians as models. Genetics has supplemented experimental embryology in enriching the understanding of the mechanism of neural induction and in posing new questions.

An early requirement for FGF signalling in the acquisition of neural cell fate in the chick embryo

BACKGROUND

In Xenopus embryos, fibroblast growth factors (FGFs) and secreted inhibitors of bone morphogenetic protein (BMP)-mediated signalling have been implicated in neural induction. The precise roles, if any, that these factors play in neural induction in amniotes remains to be established.

RESULTS

To monitor the initial steps of neural induction in the chick embryo, we developed an in vitro assay of neural differentiation in epiblast cells. Using this assay, we found evidence that neural cell fate is specified in utero, before the generation of the primitive streak or Hensen's node. Early epiblast cells expressed both Bmp4 and Bmp7, but the expression of both genes was downregulated as cells acquired neural fate. During prestreak and gastrula stages, exposure of epiblast cells to BMP4 activity in vitro was sufficient to block the acquisition of neural fate and to promote the generation of epidermal cells. Fgf3 was also found to be expressed in the early epiblast, and ongoing FGF signalling in epiblast cells was required for acquisition of neural fate and for the suppression of Bmp4 and Bmp7 expression.

CONCLUSIONS

The onset of neural differentiation in the chick embryo occurs in utero, before the generation of Hensen's node. Fgf3, Bmp4 and Bmp7 are each expressed in prospective neural cells, and FGF signalling appears to be required for the repression of Bmp expression and for the acquisition of neural fate. Subsequent exposure of epiblast cells to BMPs, however, can prevent the generation of neural tissue and induce cells of epidermal character.

Ectopic noggin blocks sensory and nonsensory organ morphogenesis in the chicken inner ear

Bone morphogenetic protein 4 (Bmp4) is expressed during multiple stages of development of the chicken inner ear. At the otocyst stage, Bmp4 is expressed in each presumptive sensory organ, as well as in the mesenchymal cells surrounding the region of the otocyst that is destined to form the semicircular canals. After the formation of the gross anatomy of the inner ear, Bmp4 expression persists in some sensory organs and restricted domains of the semicircular canals. To address the role of this gene in inner ear development, we blocked BMP4 function(s) by delivering one of its antagonists, Noggin, to the developing inner ear in ovo. Exogenous Noggin was delivered to the developing otocyst by using a replication-competent avian retrovirus encoding the Noggin cDNA (RCAS-N) or implanting beads coated with Noggin protein. Noggin treatment resulted in a variety of phenotypes involving both sensory and nonsensory components of the inner ear. Among the nonsensory structures, the semicircular canals were the most sensitive and the endolymphatic duct and sac most resistant to exogenous Noggin. Noggin affected the proliferation of the primordial canal outpouch, as well as the continual outgrowth of the canal after its formation. In addition, Noggin affected the structural patterning of the cristae, possibly via a decrease of Msx1 and p75NGFR expression. These results suggest that BMP4 and possibly other BMPs are required for multiple phases of inner ear development.

Seizure sensitivity and GABAergic modulation of ethanol sensitivity in selectively bred FAST and SLOW mouse lines

FAST and SLOW selected mouse lines were bred for differences in locomotor response to low-dose ethanol. FAST mice exhibit an extreme stimulant response and SLOW mice exhibit locomotor depression at the same ethanol dose. We tested the hypothesis that gamma-aminobutyric acid (GABA) systems modulate ethanol's stimulant effects by examining convulsant responses to GABAA receptor ligands, and by assessing the effects of GABAA and GABAB ligands on locomotor activity in the presence and absence of EtOH. FAST mice were more sensitive to the convulsant effects of GABAA drugs, and to one of two non-GABAergic drugs also tested. FAST and SLOW mice differed in locomotor responses to two benzodiazepines, but not to other GABAA receptor ligands. Ethanol's stimulant effects were not selectively altered by bicuculline or picrotoxin. The selected lines differed in sensitivity to the locomotor depressant effects of the GABAB agonist, baclofen. Ethanol-stimulated activity of FAST mice was inhibited by baclofen, and this effect was reversed by administration of the GABAB antagonist, CGP-35348. These GABAB receptor mediated effects were replicated in DBA/2J inbred mice that exhibit extreme sensitivity to ethanol's stimulant effects. In summary, we found moderate to strong evidence that some sites on the GABAA receptor complex were altered as a consequence of selection of FAST and SLOW mice, but found little support for GABAA mediation of EtOH-stimulated activity. In contrast, we found moderate evidence for differential alteration of GABAB receptor function; however, GABAB receptor involvement in ethanol-stimulated activity was strongly supported by results in the selected lines and an inbred strain.