FISH mapping and molecular organization of the major repetitive sequences of tomato

This paper presents a bird’s-eye view of the major repeats and chromatin types of tomato. Using fluorescence in-situ hybridization (FISH) with Cot-1, Cot-10 and Cot-100 DNA as probes we mapped repetitive sequences of different complexity on pachytene complements. Cot-100 was found to cover all heterochromatin regions, and could be used to identify repeat-rich clones in BAC filter hybridization. Next we established the chromosomal locations of the tandem and dispersed repeats with respect to euchromatin, nucleolar organizer regions (NORs), heterochromatin, and centromeres. The tomato genomic repeats TGRII and TGRIII appeared to be major components of the pericentromeres, whereas the newly discovered TGRIV repeat was found mainly in the structural centromeres. The highly methylated NOR of chromosome 2 is rich in [GACA]₄, a microsatellite that also forms part of the pericentromeres, together with [GA]₈, [GATA]₄ and Ty1-copia. Based on the morphology of pachytene chromosomes and the distribution of repeats studied so far, we now propose six different chromatin classes for tomato: (1) euchromatin, (2) chromomeres, (3) distal heterochromatin and interstitial heterochromatic knobs, (4) pericentromere heterochromatin, (5) functional centromere heterochromatin and (6) nucleolar organizer region.     

Tunica media of aorta and pulmonary trunk in relation to internal calibres in transposition of great arteries,in aortic and pulmonary atresia and in normal hearts

Summary In a post mortem material of 17 cases of transposition of the great arteries (TGA) from patients with an age range from birth to two years and ten months after birth, the internal calibres of the great arteries and the ostia of the heart proved to be the same as in normal hearts. Furthermore, the media of the ascending aorta and pulmonary trunk showed no adaptation to the abnormal circulatory conditions in 15 cases of TGA with an age range from birth up to 51/2 months: in both great arteries the thickness of the tunica media and the packing density of its elastic fibres were the same as in normal hearts. However, adaptation of the tunica media of the pulmonary trunk to the abnormal circulatory conditions: increased media thickness, was found in the two remaining cases, older than 12 months.In 7 cases of pulmonary atresia (age from 1 day to 12 months) and in 9 cases of aortic atresia (age from 2 days to 37 days) the following observations were made. Vessels with reduced or absent function (ascending aorta in aortic atresia and pulmonary trunk in pulmonary atresia) showed a markedly different structure. In aortic atresia the internal calibre and thickness of the media of the ascending aorta were markedly reduced, whereas the packing density of the elastic fibres of the media remained the same as in normal hearts. In pulmonary atresia the pulmonary trunk showed large variations in internal calibre, whereas both media thickness and the packing density of its elastic fibres remained the same as in normal hearts. When the markedly enlarged single functional vessels (the pulmonary trunk in aortic atresia and the ascending aorta in pulmonary atresia) were compared no significant differences between their internal calibre, media thickness and the packing density of the elastic fibres were found indicating similar adaptation to the abnormal but comparable functional load of acting as sole arterial trunk.We are indebted to Prof. Dr. J. Moll for his help, to Dr. J.J. Willemse for statistical calculations, to Mr. P. Zondervan, M.D. (Dept. of Pathology I), for supply of material and to Mrs. L. Silvis for histo-technical assistance     

CD1 assembly and the formation of CD1-antigen complexes

The CD1 antigen presentation system presents lipid antigens to effector T cells, which have diverse roles in antimicrobial responses, antitumor immunity and in regulating the balance between tolerance and autoimmunity. The trafficking of CD1 molecules and lipid antigens facilitates their intersection and binding in specific intracellular compartments. Recent studies have now identified unexpected accessory molecules that are critical to CD1 assembly and lipid loading. The atomic structures of CD1-antigen complexes have defined both the orientation of polar headgroups between the alpha1 and alpha2 helices of CD1 and the manner in which distinct CD1 isoforms bind a range of lipids that have different lengths and numbers of hydrocarbon chains.     

Chicks from a high and low feather pecking line of laying hens differ in apomorphine sensitivity

Proactive rodents show a larger behavioral response to apomorphine (APO) than reactive copers, suggesting a more sensitive DA system in proactive individuals. Previously, chicks from a high feather pecking (HFP) and low feather pecking line (LFP) have been suggested to display a proactive and reactive coping strategy, respectively. Therefore, at approximately 4 weeks of age, the behavior of 48 LFP and 48 HFP chicks in response to an APO injection was studied using an open field. Another objective of the present study was to determine whether behavioral variation (in an open field) between HFP and LFP birds, after APO injection, is also reflected by variation of D(1) and D(2) receptor densities in the brain. Receptor binding capacities were assessed by measuring specific binding of tritiated D(1) and D(2) receptor ligands in different regions of the brain of control HFP and LFP chicks. In the present study, it is shown that indeed HFP chicks display a more enhanced behavioral response to acute APO treatment (0.5 mg/kg BW) than LFP birds in an open field. This difference was not reflected by variation of D(1) and D(2) receptor densities in the brain between both lines.     

Capacitation-dependent concentration of lipid rafts in the apical ridge head area of porcine sperm cells

Lipid architecture of the plasma membrane plays an important role in the capacitation process of the sperm cell. During this process, an increase in membrane fluidity takes place, which coincides with a redistribution of cholesterol to the apical region of the head plasma membrane and subsequently an efflux of cholesterol. Cholesterol is also a major player in the formation of lipid rafts or microdomains in the membrane. Lipid rafts favour specific protein-protein interactions by concentrating certain proteins in these microdomains while excluding others. In this study, we investigated the organization of lipid rafts during in vitro capacitation of boar sperm cells. We report on the presence of the lipid raft-specific proteins caveolin-1 and flotillin-1 in sperm cells. Capacitation induced a change in membrane distribution of these proteins. Lipid analysis on detergent-resistant membranes (DRMs) of sperm cells indicated that capacitation induces a lipid raft concentration rather than a disintegration of lipid rafts, because the total amount of lipid in the DRM fraction remained unaltered. Using a proteomic approach, we identified several major DRM proteins, including proteins involved in capacitation-dependent processes and zona pellucida binding. Our data indicate that sperm raft reorganization may facilitate capacitation-specific signalling events and binding to the zona pellucida.     

Mechanotransduction of bone cells<Emphasis Type="Italic">in vitro</Emphasis>: Mechanobiology of bone tissue

Mechanical force plays an important role in the regulation of bone remodelling in intact bone and bone repair. In vitro, bone cells demonstrate a high responsiveness to mechanical stimuli. Much debate exists regarding the critical components in the load profile and whether different components, such as fluid shear, tension or compression, can influence cells in differing ways. During dynamic loading of intact bone, fluid is pressed through the osteocyte canaliculi, and it has been demonstrated that fluid shear stress stimulates osteocytes to produce signalling molecules. It is less clear how mechanical loads act on mature osteoblasts present on the surface of cancellous or trabecular bone. Although tissue strain and fluid shear stress both cause cell deformation, these stimuli could excite different signalling pathways. This is confirmed by our experimental findings, in human bone cells, that strain applied through the substrate and fluid flow stimulate the release of signalling molecules to varying extents. Nitric oxide and prostaglandin E₂ values increased by between two- and nine-fold after treatment with pulsating fluid flow (0.6±0.3 Pa). Cyclic strain (1000 μstrain) stimulated the release of nitric oxide two-fold, but had no effect on prostaglandin E₂. Furthermore, substrate strains enhanced the bone matrix protein collagen I two-fold, whereas fluid shear caused a 50% reduction in collagen I. The relevance of these variations is discussed in relation to bone growth and remodelling. In applications such as tissue engineering, both stimuli offer possibilities for enhancing bone cell growth in vitro.     

Monomethylfumarate affects polarization of monocyte-derived dendritic cells resulting in down-regulated Th1 lymphocyte responses

Psoriasis vulgaris, a type-1 cytokine-mediated chronic skin disease, can be treated successfully with fumaric acid esters (FAE). Beneficial effects of this medication coincided with decreased production of IFN-gamma. Since dendritic cells (DC) regulate the differentiation of T helper (Th) cells, this study focussed on effects of monomethylfumarate (MMF, bioactive metabolite of FAE) on polarization of monocyte-derived DC. MMF-incubated, lipo-polysaccharide-stimulated DC (MMF-DC) produced dramatically (p<0.05) reduced levels of IL-12p70 and IL-10 (8+/-4% and 20+/-4%, respectively) compared to control DC. MMF-DC were mature. MMF affected polarization of DC irrespective of polarization factor(s) and ligands for the various Toll-like receptors used. Coculture of MMF-DC with naive and primed allogenous Th cells resulted in lymphocytes producing less IFN-gamma, i.e. 59% and 54% of that by the respective Th cells cocultured with control DC. IL-4 production by primed, but not naive Th cells cocultured with MMF-DC was decreased as compared to cocultures with control DC. IL-10 production by naive and primed Th cells cocultured with MMF-DC and control DC did not differ. In addition, MMF inhibited LPS-induced NF-kappaB activation in DC. Together, beneficial effects of FAE in psoriasis involve modulation of DC polarization by MMF such that these cells down-regulate IFN-gamma production by Th cells.     

Multiple dimensions of familial psychopathology affect risk of mood disorder in children of bipolar parents.

The aim of our study was to determine whether familial loading of unipolar disorder, bipolar disorder, and substance use disorder are associated with DSM-IV mood disorders in adolescents at risk for bipolar disorder. One hundred and forty adolescents aged 12-21 years of 86 bipolar parents participated in the study. Lifetime DSM-IV diagnoses of the bipolar offspring were assessed with the Schedule for Affective Disorders and Schizophrenia for School Age Children Kiddie-SADS-Present and Lifetime Version (SADS-PL). Parents were interviewed using the Family History Research Diagnostic Criteria (FH-RDC) which were used to calculate a continuous familial loading score (FL) for unipolar disorder, bipolar disorder, and for substance use disorder in first- and second-degree relatives of the adolescents. FL for unipolar disorder and substance use disorder were strong and independent predictors for lifetime mood disorders in the adolescents. The gender adjusted hazard ratios for mood disorders in the children were 1.5 (95% confidence interval (CI) = 1.2-2.0) for FL of unipolar disorder and 1.8 (95% CI = 1.3-2.4) for FL of substance use disorder. Expression of mood disorders in children of bipolar parents varies with the degree of additional FL of unipolar disorder and substance use disorder in the extended family.