Dynamics of fat cell turnover in humans

Obesity is increasing in an epidemic manner in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells (adipocytes) is thought to be most important. Here we show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese individuals, even after marked weight loss, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analysing the integration of 14C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in early onset obesity, suggesting a tight regulation of fat cell number in this condition during adulthood. The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.     

Biology and defensive secretion of myrmecophilous Thiasophila spp. (Coleoptera: Staphylinidae: Aleocharinae) associated with the Formica rufa species group

Various aspects of the biology of the myrmecophilous Thiasophila angulata and T. szujeckii (Staphylinidae; Aleocharinae), mainly associated with the Formica rufa species group, are studied. The composition of defensive gland secretions from adults of T. angulata has been analysed. The complete development (egg-L_1-3-pupa-adult form), including adult overwintering, of both species takes place solely in ant nests. Under laboratory conditions, this lasts for about 22 days in T. angulata, and the period elapsing between the old and new generations of insects is approximately two months. The mean fecundity of adults of this species (28 eggs) was determined, as well as the duration of its reproductive period (mean 28.5 days), and lifespan (mean 67 days). In natural conditions T. angulata, found within nests of Formica polyctena and F. rufa, produces three generations, and the sibling species T. szujeckii one generation per year. These two species differ in their phenologies and abundance dynamics of adults and larvae, which is linked to the size and temperature regime of the host nest. The results of this study uphold the recent separation of T. angulata and T. szujeckii based on morphological features of adults and selected molecular markers. Adults and larvae of T. angulata forage on both live and dead food items accumulated by the host, as well as on the host’s eggs and larvae. Both the beetle larvae and adults remain unmolested among the host workers. The adults use their defensive gland secretions, which contains substantial quantities of toxic quinones, when necessary. According to the current categories of myrmecophiles, T. angulata (and by analogy, T. szujeckii as well) should be classified as a species wholly integrated with the host.     

Identification of common variants associated with human hippocampal and intracranial volumes

Identifying genetic variants influencing human brain structures may reveal new biological mechanisms underlying cognition and neuropsychiatric illness. The volume of the hippocampus is a biomarker of incipient Alzheimer's disease and is reduced in schizophrenia, major depression and mesial temporal lobe epilepsy. Whereas many brain imaging phenotypes are highly heritable, identifying and replicating genetic influences has been difficult, as small effects and the high costs of magnetic resonance imaging (MRI) have led to underpowered studies. Here we report genome-wide association meta-analyses and replication for mean bilateral hippocampal, total brain and intracranial volumes from a large multinational consortium. The intergenic variant rs7294919 was associated with hippocampal volume (12q24.22; N = 21,151; P = 6.70 × 10(-16)) and the expression levels of the positional candidate gene TESC in brain tissue. Additionally, rs10784502, located within HMGA2, was associated with intracranial volume (12q14.3; N = 15,782; P = 1.12 × 10(-12)). We also identified a suggestive association with total brain volume at rs10494373 within DDR2 (1q23.3; N = 6,500; P = 5.81 × 10(-7)).     

Heat-shock protein 60 translocates to the surface of apoptotic cells and differentiated megakaryocytes and stimulates phagocytosis

Heat-shock protein 60 (Hsp60) is a highly conserved stress protein which has chaperone functions in prokaryotes and mammalian cells. Hsp60 is associated with the mitochondria and the plasma membrane through phosphorylation by protein kinase A, and is incorporated into lipid membranes as a protein-folding chaperone. Its diverse intracellular chaperone functions include the secretion of proteins where it maintains the conformation of precursors and facilitates their translocation through the plasma membrane. We report here that Hsp60 is concentrated in apoptotic membrane blebs and translocates to the surface of cells undergoing apoptosis. Hsp60 is also enriched in platelets derived from terminally differentiated megakaryocytes and expressed at the surface of senescent platelets. Furthermore, the exposure of monocytic U937 cells to Hsp60 enhanced their phagocytic activity. Our results suggests that externalized Hsp60 in apoptotic cells and senescent platelets influences events subsequent to apoptosis, such as the clearance of apoptotic cells by phagocytes.     

Megasatellites: a new class of large tandem repeats discovered in the pathogenic yeast Candida glabrata

Megasatellites are DNA tandem arrays made of large motifs; they were discovered in the yeast Candida glabrata. They are widespread in this species (40 copies) but are not found in any other hemiascomycete so far, raising the intriguing question of their origin. They are found mainly in genes encoding cell wall products, suggesting that megasatellites were selected for a function linked to cell–cell adhesion or to pathogenicity. Their putative role in promoting genome rearrangements by interfering with DNA replication will also be discussed.     

The algal flora of the campus of Brigham Young University, Provo, Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The algal flora of the Brigham Young University campus is more diverse than previously thought. Sixty - eight genera containing 160 species of Chlorophyta, Euglenophyta, Chrysophyta, and Cyanophyta were collected and identified. The greatest number of species was obtained from a small pond in the arboretum, with progressively fewer species obtained in the irrigation canal partly surrounding the campus and in specialized habitats in the greenhouses.     

Variants modulating the expression of a chromosome domain encompassing PLAG1 influence bovine stature

We report mapping of a quantitative trait locus (QTL) with a major effect on bovine stature to a ～780-kb interval using a Hidden Markov Model-based approach that simultaneously exploits linkage and linkage disequilibrium. We re-sequenced the interval in six sires with known QTL genotype and identified 13 clustered candidate quantitative trait nucleotides (QTNs) out of >9,572 discovered variants. We eliminated five candidate QTNs by studying the phenotypic effect of a recombinant haplotype identified in a breed diversity panel. We show that the QTL influences fetal expression of seven of the nine genes mapping to the ～780-kb interval. We further show that two of the eight candidate QTNs, mapping to the PLAG1-CHCHD7 intergenic region, influence bidirectional promoter strength and affect binding of nuclear factors. By performing expression QTL analyses, we identified a splice site variant in CHCHD7 and exploited this naturally occurring null allele to exclude CHCHD7 as single causative gene.     

A synonymous variant in IRGM alters a binding site for miR-196 and causes deregulation of IRGM-dependent xenophagy in Crohn's disease

Susceptibility to Crohn's disease, a complex inflammatory disease, is influenced by common variants at many loci. The common exonic synonymous SNP (c.313C>T) in IRGM, found in strong linkage disequilibrium with a deletion polymorphism, has been classified as non-causative because of the absence of an alteration in the IRGM protein sequence or splice sites. Here we show that a family of microRNAs (miRNAs), miR-196, is overexpressed in the inflammatory intestinal epithelia of individuals with Crohn's disease and downregulates the IRGM protective variant (c.313C) but not the risk-associated allele (c.313T). Subsequent loss of tight regulation of IRGM expression compromises control of intracellular replication of Crohn's disease-associated adherent invasive Escherichia coli by autophagy. These results suggest that the association of IRGM with Crohn's disease arises from a miRNA-based alteration in IRGM regulation that affects the efficacy of autophagy, thereby implicating a synonymous polymorphism as a likely causal variant.     

Genome-wide association study identifies new susceptibility loci for Crohn disease and implicates autophagy in disease pathogenesis

We present a genome-wide association study of ileal Crohn disease and two independent replication studies that identify several new regions of association to Crohn disease. Specifically, in addition to the previously established CARD15 and IL23R associations, we identified strong and significantly replicated associations (combined P < 10(-10)) with an intergenic region on 10q21.1 and a coding variant in ATG16L1, the latter of which was also recently reported by another group. We also report strong associations with independent replication to variation in the genomic regions encoding PHOX2B, NCF4 and a predicted gene on 16q24.1 (FAM92B). Finally, we demonstrate that ATG16L1 is expressed in intestinal epithelial cell lines and that functional knockdown of this gene abrogates autophagy of Salmonella typhimurium. Together, these findings suggest that autophagy and host cell responses to intracellular microbes are involved in the pathogenesis of Crohn disease.     

Birc2 (cIap1) regulates endothelial cell integrity and blood vessel homeostasis

Integrity of the blood vessel wall is essential for vascular homeostasis and organ function. A dynamic balance between endothelial cell survival and apoptosis contributes to this integrity during vascular development and pathological angiogenesis. The genetic and molecular mechanisms regulating these processes in vivo are still largely unknown. Here, we show that Birc2 (also known as cIap1) is essential for maintaining endothelial cell survival and blood vessel homeostasis during vascular development. Using a forward-genetic approach, we identified a zebrafish null mutant for birc2, which shows severe hemorrhage and vascular regression due to endothelial cell integrity defects and apoptosis. Using genetic and molecular approaches, we show that Birc2 positively regulates the formation of the TNF receptor complex I in endothelial cells, thereby promoting NF-kappaB activation and maintaining vessel integrity and stabilization. In the absence of Birc2, a caspase-8-dependent apoptotic program takes place that leads to vessel regression. Our findings identify Birc2 and TNF signaling components as critical regulators of vascular integrity and endothelial cell survival, thereby providing an additional target pathway for the control of angiogenesis and blood vessel homeostasis during embryogenesis, regeneration and tumorigenesis.