The gene encoding nicastrin, a major gamma-secretase component, modifies risk for familial early-onset Alzheimer disease in a Dutch population-based sample

Nicastrin regulates gamma-secretase cleavage of the amyloid precursor protein by forming complexes with presenilins, in which most mutations causing familial early-onset Alzheimer disease (EOAD) have been found. The gene encoding nicastrin (NCSTN) maps to 1q23, a region that has been linked and associated with late-onset Alzheimer disease (LOAD) in various genome screens. In 78 familial EOAD cases, we found 14 NCSTN single-nucleotide polymorphisms (SNPs): 10 intronic SNPs, 3 silent mutations, and 1 missense mutation (N417Y). N417Y is unlikely to be pathogenic, since it did not alter amyloid beta secretion in an in vitro assay and its frequency was similar in case and control subjects. However, SNP haplotype estimation in two population-based series of Dutch patients with EOAD (n=116) and LOAD (n=240) indicated that the frequency of one SNP haplotype (HapB) was higher in the group with familial EOAD (7%), compared with the LOAD group (3%) and control group (3%). In patients with familial EOAD without the APOE epsilon4 allele, the HapB frequency further increased, to 14%, resulting in a fourfold increased risk (odds ratio = 4.1; 95% confidence interval 1.2-13.3; P=.01). These results are compatible with an important role of gamma-secretase dysfunction in the etiology of familial EOAD.     

A conditionally fertile coi1 allele indicates cross-talk between plant hormone signalling pathways in Arabidopsis thaliana seeds and young seedlings

Jasmonates (JAs) regulate Arabidopsis thaliana (L.) Heynh. wound and defense responses, pollen development, and stress-related growth inhibition. Significantly, each of these responses requires COI1, an F-box protein. We fused firefly luciferase as a reporter to the JA-responsive promoter for the vegetative storage protein gene (VSP) and used this to screen for mutants that failed to express luciferase in the presence of JA, isolating a mutant designated coi1-16. Comparisons with coi1-1 and jar1-1 plants indicated that coi1-16 was only slightly more sensitive to JA than coi1-1 plants. However, whilst coi1-16 plants failed to produce viable pollen at 22 degrees C, they were fertile at 16 degrees C. Therefore, unlike the other coi1 mutants, coi1-16 could be maintained as a pure line and did not require selection. We have used coi1-16 seeds to define novel interactions between JA and other hormone signalling pathways in seed germination and in the development of young seedlings.     

Mammary leptin synthesis,milk leptin and their putative physiological roles

This paper reviews data on mammary leptin and leptin receptor gene expression as well as on blood and milk leptin levels during the pregnancy-lactation cycle in humans, rodents and ruminants, with the aim of better understanding milk leptin origin and functions. The few published papers report that leptin may be produced by different cell types in the mammary tissue, and may act as a paracrine factor on mammary epithelial cell proliferation, differentiation and/or apoptosis via adipose-epithelial and/or myoepithelial-epithelial cellular interactions. In addition to leptin synthesis, epithelial cells may transfer leptin from the blood, and these two mechanisms may account for the presence of leptin in the milk. The respective parts of these two processes remain to be determined, as well as the true milk leptin levels. Indeed, reported concentrations for milk leptin vary strongly according to species and mainly according to the milk fractions and the assay methods used. If leptin levels in milk (and specially colostrum) are found to be significant, this hormone could be involved in neonate physiology.     

Comparison of the effects of two GnRH antagonists on LH and FSH secretion,follicular growth and ovulation in the mare

The effects of two GnRH antagonists were tested in order to delay and/or synchronise ovulation in mares. Five mares received Antarelix (0.01 mg.kg(-1)), 5 mares received Cetrorelix (the same dose), 5 mares (control mares) received the vehicle intravenously, twice daily, for 8 days from the day the largest follicle reached 22 mm following prostaglandin administration. Ovulation was postponed in all mares injected with Antarelix (19.4 +/- 1.2 days after the beginning of the treatment) and in 2/5 mares injected with Cetrorelix (20 +/- 1 days) vs. 6.2 +/- 0.4 days in control mares. During the treatment, LH concentrations were strongly depressed in Antarelix and in Cetrorelix mares (1.6 +/- 0.1 and 3.8 +/- 0.5 ng.mL(-1) respectively vs. 21 +/- 2.5 ng.mL(-1) in control mares). In the 3 Cetrorelix mares which ovulated during the treatment. 2 initiated their LH surge at this moment. FSH concentrations were not affected in Antarelix or in Cetrorelix mares during the treatment (11.4 +/- 1.3 and 7.9 +/- 0.8 ng.mL(-1) respectively vs. 10.5 +/- 0.8 ng.mL(-1) in control mares). In conclusion, Antarelix seems more efficient than Cetrorelix for postponing ovulation in mares. The role of LH in antral follicular development before the preovulatory stage is confirmed.     

Secondary metabolites from Centaurea deusta with antimicrobial activity

The aerial parts of Centaurea deusta Ten. afforded in addition to several known compounds, mainly sesquiterpene lactones, one new eudesmanolide and one new elemane derivative. Structures of the new compounds were elucidated by spectroscopic methods. The in vitro antifungal and antibacterial activities of the isolated compounds was tested, using the microdilution method. All compounds tested showed high antifungal activity.     

Nitric oxide synthase II in rat skeletal muscles

Constitutive expression of nitric oxide synthase (NOS) II was found in rat hindlimb muscles by immunohistochemistry and western blotting during development from embryonic day 21 to the adult stage of 75 days. The immunohistochemical NOS II expression pattern was related to the physiological metabolic fibre types SO (slow-oxidative), FOG I, II (fast-oxidative glycolytic; I more glycolytic, II more oxidative) and FG (fast-glycolytic) and to the myosin-based fibre types I and IIA, IIB (IIX not separated) identified in serial sections by enzyme histochemistry and immunohistochemistry. In adult muscles only the small population of FOG II fibres, which is a part of both IIA and IIB fibre population, showed NOS II immunoreactivity. This is the reason that only weak NOS II expression in adult hindlimb muscles has been detected by western blotting. Hindlimb muscles of embryonic, neonatal and young rats of 8 days expressed more NOS II as compared with adult rat hindlimb muscles. This can be explained by the findings that before the age of 21 days fast fibres were metabolically undifferentiated, all of them were NOS II positive and contribute to the NOS II expression of the muscle. In muscles of diabetic rats the NOS II expression was elevated indicating an inhibition of glucose uptake into the muscle fibres of diabetic muscles. Our findings suggest that the NOS II may be designated both as constitutive and inducible.     

Negative effect of Hox gene expression on the development of the neural crest-derived facial skeleton

Diencephalic, mesencephalic and metencephalic neural crest cells are skeletogenic and derive from neural folds that do not express Hox genes. In order to examine the influence of Hox gene expression on skull morphogenesis, expression of Hoxa2, Hoxa3 and Hoxb4 in conjunction with that of the green fluorescent protein has been selectively targeted to the Hox-negative neural folds of the avian embryo prior to the onset of crest cell emigration. Hoxa2 expression precludes the development of the entire facial skeleton. Transgenic Hoxa2 embryos such as those from which the Hox-negative domain of the cephalic neural crest has been removed have no upper or lower jaws and no frontonasal structures. Embryos subjected to the forced expression of Hoxa3 and Hoxb4 show severe defects in the facial skeleton but not a complete absence of facial cartilage. Hoxa3 prevents the formation of the skeleton derived from the first branchial arch, but allows the development (albeit reduced) of the nasal septum. Hoxb4, by contrast, hampers the formation of the nasal bud-derived skeleton, while allowing that of a proximal (but not distal) segment of the lower jaw. The combined effect of Hoxa3 and Hoxb4 prevents the formation of facial skeletal structures, comparable with Hoxa2. None of these genes impairs the formation of neural derivatives of the crest. These results suggest that over the course of evolution, the absence of Hox gene expression in the anterior part of the chordate embryo was crucial in the vertebrate phylum for the development of a face, jaws and brain case, and, hence, also for that of the forebrain.     

Eya1 is required for the morphogenesis of mammalian thymus,parathyroid and thyroid

Eyes absent (Eya) genes regulate organogenesis in both vertebrates and invertebrates. Mutations in human EYA1 cause congenital Branchio-Oto-Renal (BOR) syndrome, while targeted inactivation of murine Eya1 impairs early developmental processes in multiple organs, including ear, kidney and skeletal system. We have now examined the role of Eya1 during the morphogenesis of organs derived from the pharyngeal region, including thymus, parathyroid and thyroid. The thymus and parathyroid are derived from 3rd pharyngeal pouches and their development is initiated via inductive interactions between neural crest-derived arch mesenchyme, pouch endoderm, and possibly the surface ectoderm of 3rd pharyngeal clefts. Eya1 is expressed in all three cell types during thymus and parathyroid development from E9.5 and the organ primordia for both of these structures failed to form in Eya1(-/-) embryos. These results indicate that Eya1 is required for the initiation of thymus and parathyroid gland formation. Eya1 is also expressed in the 4th pharyngeal region and ultimobranchial bodies. Eya1(-/-) mice show thyroid hypoplasia, with severe reduction in the number of parafollicular cells and the size of the thyroid lobes and lack of fusion between the ultimobranchial bodies and the thyroid lobe. These data indicate that Eya1 also regulates mature thyroid gland formation. Furthermore, we show that Six1 expression is markedly reduced in the arch mesenchyme, pouch endoderm and surface ectoderm in the pharyngeal region of Eya1(-/-) embryos, indicating that Six1 expression in those structures is Eya1 dependent. In addition, we show that in Eya1(-/-) embryos, the expression of Gcm2 in the 3rd pouch endoderm is undetectable at E10.5, however, the expression of Hox and Pax genes in the pouch endoderm is preserved at E9.5-10.5. Finally, we found that the surface ectoderm of the 3rd and 4th pharyngeal region show increased cell death at E10.5 in Eya1(-/-) embryos. Our results indicate that Eya1 controls critical early inductive events involved in the morphogenesis of thymus, parathyroid and thyroid.