Genetic mapping and developmental timing of transmission ratio distortion in a mouse interspecific backcross

Background

Sheep carcasses with yellow fat are sporadically observed at Norwegian slaughter houses. This phenomenon is known to be inherited as a recessive trait, and is caused by accumulation of carotenoids in adipose tissue. Two enzymes are known to be important in carotenoid degradation in mammals, and are therefore potential candidate genes for this trait. These are beta-carotene 15,15'-monooxygenase 1 (BCMO1) and the beta-carotene oxygenase 2 (BCO2).

Results

In the present study the coding region of the BCMO1 and the BCO2 gene were sequenced in yellow fat individuals and compared to the corresponding sequences from control animals with white fat. In the yellow fat individuals a nonsense mutation was found in BCO2 nucleotide position 196 (c.196C>T), introducing a stop codon in amino acid position 66. The full length protein consists of 575 amino acids. In spite of a very low frequency of this mutation in the Norwegian AI-ram population, 16 out of 18 yellow fat lambs were found to be homozygous for this mutation.

Conclusion

In the present study a nonsense mutation (c.196C>T) in the beta-carotene oxygenase 2 (BCO2) gene is found to strongly associate with the yellow fat phenotype in sheep. The existence of individuals lacking this mutation, but still demonstrating yellow fat, suggests that additional mutations may cause a similar phenotype in this population. The results demonstrate a quantitatively important role for BCO2 in carotenoid degradation, which might indicate a broad enzyme specificity for carotenoids. Animals homozygous for the mutation are not reported to suffer from any negative health or development traits, pointing towards a minor role of BCO2 in vitamin A formation. Genotyping AI rams for c.196C>T can now be actively used in selection against the yellow fat trait.     

Stimulation of Cultured Melanocytes in Medium Containing a Serum Substitute: Ultroser-G

Melanocyte cultures were established and maintained routinely in Ham's F-10 medium containing 12-O-tetradecanoyl-phorbol-13-acetate (TPA), isobutylmethylxanthine (IBMX), cholera toxin (CT) and fetal calf serum (FCS). Three serum substitutes (Ultroser-G, Nutridoma-Hu and Nutricyte-H) were tested in order to obtain a medium without FCS having a more constant composition. Melanocyte proliferation was examined in long-term culture experiments by in situ cell counts at different periods of time. Only with Ultroser-G (1-2%) was the proliferation of melanocytes maintained without both FCS and CT, whereas the addition of the other two serum substitutes resulted in stabilization of melanocyte densities in the cultures up to 28 days. In the medium containing 1% Ultroser-G and IBMX without TPA minimal or no increases in melanocyte density were found. Addition of basic fibroblast growth factor (bFGF, 1 ng/ml) to the medium without TPA resulted in a partial restimulation of growth in different experiments. In this system with 1% Ultroser-G and 1 ng/ml bFGF, IBMX could also be replaced by other factors (dbcAMP LTC4 and a purified form of α-melanocyte stimulating hormone). The culture medium with 1% Ultroser-G containing TPA and IBMX is now used for routine melanocyte culture. In this medium TPN/IBMX can easily be replaced by bFGF/dbcAMP with optimal growth stimulation. The combination bFGF/α-MSH and other more physiological stimulators offers an alternative to study responses of melanocytes in culture with respect to proliferation, metabolism, and phenotype.     

Moving instead of asking? Performance-based tests and BASFI-questionnaire measure different aspects of physical function in ankylosing spondylitis

Introduction

Ankylosing Spondylitis (AS) is characterised by limitations in physical function. The Bath Ankylosing Spondylitis Functional Index (BASFI) is considered to be the gold-standard to assess physical function in AS patients. However, the BASFI questionnaire is a self-reported outcome measure and susceptible to subjective interpretation (under- or over-estimation). More objective outcome measures, like performance-based tests, could provide an objective outcome measurement for the evaluation of limitations in physical function. Therefore, the primary aim of this study was to determine the association between performance-based measures and the BASFI questionnaire.

Methods

In this cross-sectional study 126 AS patients completed the BASFI questionnaire and eight performance-based tests based on BASFI-items. Each test received three scores: one for performance (time or points) and a score for exertion and pain experienced during performance (using modified Borg-scale and VAS 0-100 mm, respectively). Linear regression analyses were used to assess the associations between the BASFI questionnaire and performance-based tests.

Results

The univariable association between performance and BASFI-score was moderate with a R-square of 0.31 and Beta of 0.56 (p's < 0.05). In a multivariable analysis, the association between performance, exertion and pain on the one hand and BASFI-score on the other was assessed; R-square increased to 0.54: the Beta's for exertion and pain during performance were 0.38 and 0.26, respectively; the Beta for performance decreased to 0.19 (p's < 0.05).

Conclusions

This study demonstrates that alongside actual performance, patients seem to incorporate exertion and pain in their assessment of perceived physical function on the BASFI questionnaire. Performance-based tests could provide an objective outcome measurement for the evaluation of physical function and give relevant new information in addition to the BASFI questionnaire.     

Rheumatoid factor and anti-citrullinated protein antibody positivity,but not level,are associated with increased mortality in patients with rheumatoid arthritis: results from two large independent cohorts

Introduction

This study aimed to investigate rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) status and levels as predictors of mortality in two large cohorts of patients with early inflammatory arthritis (EIA).

Methods

Data from the Norfolk Arthritis Register (NOAR) and Leiden Early Arthritis Clinic (EAC) cohorts were used. At baseline, patients had demographic data and smoking status recorded; RF, ACPA and inflammatory markers were measured in the local laboratories. Patients were flagged with national death registers until death or censor date. Antibody status was stratified as negative, low or high positive by RF and ACPA levels individually. In addition, patients were grouped as seronegative, RF positive, ACPA positive or double antibody (RF and ACPA) positive. Cox regression models explored associations between antibody status and mortality adjusting for age, sex, smoking status, inflammatory markers and year of enrolment.

Results

A total of 4962 patients were included, 64% were female. Median age at onset was 56 (NOAR) and 54 (EAC) years. In NOAR and EAC respectively, 35% and 42% of patients were ACPA/RF positive. When antibody status was stratified as negative, low or high positive, there were no consistent findings between the two cohorts. Double antibody positivity was associated with excess mortality in both cohorts compared to seronegative patients: NOAR and EAC respective adjusted HR (95% confidence interval) 1.35 (1.09 to 1.68) and 1.58 (1.16 to 2.15).

Conclusions

Patients with EIA who are seropositive for both RF and ACPA have increased mortality compared to those who are single positive or seronegative. Antibody level in seropositive patients was not consistently associated with excess mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0483-3) contains supplementary material, which is available to authorized users.     

Ultrastructure of crystalloid inclusions in the dog and rat epididymis

Fine structural studies of the epididymis of mature mongrel dogs and of Sprague-Dawley rats were undertaken in conjunction with research dealing with the effects of vasectomy upon this organ. This paper reports the observation of crystalloid and lamellar inclusions present in these species following fixation of the epididymis in 5 % glutaraldehyde, post-fixation in osmium, and routine processing for electron microscopy. In the dog, crystalloid inclusions were observed within the cauda epididymidis of unoperated and vasectomized animals. They were found within the apical cytoplasm of principal cells in association with the Golgi apparatus and endoplasmic reticulum, and in some instances, in close proximity to the nucleus. These crystalloids exhibited a 12 nm periodicity and often measured over 3 μm in length. In the rat, two types of inclusions were found, one within mitochondria of clear cells from unoperated animals and another within membrane-bound bodies of principal cells from the caput epididymidis of unoperated and vasectomized animals. The mitochondria which contained inclusions were basally located and were observed in stacks of up to eight elongate mitochondria each. The mitochondrial inclusions exhibited a complex lamellar structure with an approximate periodicity of 36 nm. In contrast, the crystalloid inclusions found within principal cells were sequestered within supranuclear cytoplasmic bodies which increased in number with age. Such crystalloids exhibited a linear periodicity of 11–13.5 nm, but the precise lattice structure remains to be determined. Although certain aspects of the morphology of these bodies suggests a relationship to microbodies, we have been unable to demonstrate catalase activity within them. At present, neither the origin of crystalloid structures described, nor their relationship to epididymal physiology is clear.     

Diet of bluegill Lepomis macrochirus in a South African reservoir during winter and summer

Alien fishes are considered a major threat to aquatic biodiversity in South Africa, yet relatively little regional information on their biology and ecology is available for many of these species. Seasonal changes in the diet of the bluegill Lepomis macrochirus in Howieson’s Poort Dam, Grahamstown, were assessed during summer and winter in 2014–2015, using stomach content analysis. In winter, juvenile and adult fish diets were dominated by crustacean zooplankton and insects, respectively. In summer, juvenile fish fed on crustaceans and insects, whereas adults consumed mostly fish eggs, indicating a potential impact by these invasive fish on native fish through oophagy.     

Decidual cells in the human ovary at term. I. Incidence, gross anatomy and ultrastructural features of merocrine secretion

Decidual tissue occurring within the human ovarian cortex was examined by light and electron microscopy. Of 21 ovarian specimens obtained at term (36-42 weeks of gestation), decidual cells were confirmed in each. Decidual cells were found within the tunica albuginea as single cells, in nodules, in polyps or in confluent sheets. Decidual cells exhibited several characteristics of cells engaged in secretory activity: abundant rough and smooth endoplasmic reticulum, numerous profiles of the Golgi complex and a large, euchromatic nucleus devoid of heterochromatin and displaying a prominent fibrous lamina. Peduncular protrusions at the periphery of the cell contained numerous dense bodies 0.4-0.9 micron in diameter. These dense bodies were bounded by a single membrane and contained granular subunits 30-60 nm in diameter. These granular subunits were observed in the process of apparent exocytosis, as well as free in the extracellular space. Secretory bodies and their granular content also were observed both in the region of the Golgi complex and partially extruded into peduncular processes. By far the greatest number of secretory bodies occurred within peduncular processes where they may be stored prior to release. Migration of a secretory body into a peduncular process and exocytosis from such a process appears to be an unusual mode of meocrine secretion, perhaps unique to decidual cells.     

Ecology of spiders inhabiting abandoned mammal burrows in South African savanna

Summary We marked the sites chosen by 338 foundress queens of two desert ant species (Veromessor pergandei and Myrmecocystus flaviceps) and monitored changes in the spacing of both species and the foraging activity at V. pergandei young nests. Although the long established colonies of both species tend intraspecifically toward regular dispersion, queens of both species were intraspecifically clumped. After 3 months, when the first workers emerged, the young colonies (reduced to a total of 42 colonies) were randomly spaced intraspecifically. We also followed the spatial patter of queens with respect to established colonies of both species. Queens founded nests away from the nests of all established colonies on the site. After three months, the young colonies were dispersed away from conspecifics only. During June through August 1986, we censused the number of foragers at the surviving V. pergandei nests. Young colonies that were more active also tended to be far from established conspecifics in July and August. There was no correlation of forating activity with distance to heterospecific established colonies in any month. These results indicate that established conspecifics may reduce the survivorship of young ant colonies.     

A freeze-fracture study of exocytosis and reflexive gap junctions in human ovarian decidual cells

Fine-structural features of ovarian decidual cells and their mode of secretion were examined by means of freeze-fracture microscopy. Unique cortical peduncular processes contained secretory vesicles within the expanded peduncle tip, the membrane-leaflets of which exhibited a particle-poor E face adjacent to the vesicle lumen and a P face containing a greater particle number. Exocytosis from attached peduncles involved release of vesicular profiles 40-55 nm in diameter; small particles 8.5-11.5 nm in diameter were also observed at degranulation sites. In fractures revealing the E face of the plasmalemma, cytoplasmic portals at the bases of peduncular stalks were distinguishable from endocytic vesicles. The frequent occurrence of reflexive gap junctions associated with peduncles was shown by freeze-fracture. However, there appeared to be no consistent spatial relationship between gap junctions, secretory peduncles, or sites of exocytosis. Freeze-fracture analysis of the topography of reflexive gap junctional profiles revealed that such gap junctions share basic similarities with intercellular gap jum particle-free aisles. The finding in the present study of reflexive gap junctions occurring between peduncles and the cell soma, as well as between peduncles, suggests that the original definitiof the same cell should be broadened to include any gap junctional specialization formed between portions of the plasma membrane of one cell.     

Molecular evolution of bacteriophages: evidence of selection against the recognition sites of host restriction enzymes

Restriction enzymes produced by bacteria serve as a defense against invading bacteriophages, and so phages without other protection would be expected to undergo selection to eliminate recognition sites for these enzymes from their genomes. The observed frequencies of all restriction sites in the genomes of all completely sequenced DNA phages (T7, lambda, phi X174, G4, M13, f1, fd, and IKe) have been compared to expected frequencies derived from trinucleotide frequencies. Attention was focused on 6-base palindromes since they comprise the typical recognition sites for type II restriction enzymes. All of these coliphages, with the exception of lambda and G4, exhibit significant avoidance of the particular sequences that are enterobacterial restriction sites. As expected, the sequenced fraction of the genome of phi 29, a Bacillus subtilis phage, lacks Bacillus restriction sites. By contrast, the RNA phage MS2, several viruses that infect eukaryotes (EBV, adenovirus, papilloma, and SV40), and three mitochondrial genomes (human, mouse, and cow) were found not to lack restriction sites. Because the particular palindromes avoided correspond closely with the recognition sites for host enzymes and because other viruses and small genomes do not show this avoidance, it is concluded that the effect indeed results from natural selection.