Roberto Cusano

Low-Pass DNA Sequencing of 1200 Sardinians Reconstructs European Y-Chromosome Phylogeny

Examining Y The evolution of human populations has long been studied with unique sequences from the nonrecombining, male-specific Y chromosome (see the Perspective by Cann). Poznik et al. (p. 562) examined 9.9 Mb of the Y chromosome from 69 men from nine globally divergent populations—identifying population and individual specific sequence variants that elucidate the evolution of the Y chromosome. Sequencing of maternally inherited mitochondrial DNA allowed comparison between the relative rates of evolution, which suggested that the coalescence, or origin, of the human Y chromosome and mitochondria both occurred approximately 120 thousand years ago. Francalacci et al. (p. 565) investigated the sequence divergence of 1204 Y chromosomes that were sampled within the isolated and genetically informative Sardinian population. The sequence analyses, along with archaeological records, were used to calibrate and increase the resolution of the human phylogenetic tree. Local human demographic history is inferred from in-depth DNA sequence analysis of Sardinian mens Y chromosomes. [Also see Perspective by Cann] Genetic variation within the male-specific portion of the Y chromosome (MSY) can clarify the origins of contemporary populations, but previous studies were hampered by partial genetic information. Population sequencing of 1204 Sardinian males identified 11,763 MSY single-nucleotide polymorphisms, 6751 of which have not previously been observed. We constructed a MSY phylogenetic tree containing all main haplogroups found in Europe, along with many Sardinian-specific lineage clusters within each haplogroup. The tree was calibrated with archaeological data from the initial expansion of the Sardinian population ~7700 years ago. The ages of nodes highlight different genetic strata in Sardinia and reveal the presumptive timing of coalescence with other human populations. We calculate a putative age for coalescence of ~180,000 to 200,000 years ago, which is consistent with previous mitochondrial DNA–based estimates.

Complete genome sequence of chloroplast DNA (cpDNA) of Chlorella sorokiniana

Abstract The complete chloroplast genome sequence of Chlorella sorokiniana strain (SAG 111–8u2009k) is presented in this study. The genome consists of circular chromosomes of 109,811u2009bp, which encode a total of 109 genes, including 74 proteins, 3 rRNAs and 31 tRNAs. Moreover, introns are not detected and all genes are present in single copy. The overall AT contents of the C. sorokiniana cpDNA is 65.9%, the coding sequence is 59.1% and a large inverted repeat (IR) is not observed.

Complete genome sequence of mitochondrial DNA (mtDNA) of Chlorella sorokiniana.

Abstract The complete sequence of mitochondrial genome of the Chlorella sorokiniana strain (SAG 111-8u2009k) is presented in this work. Within the Chlorella genus, it represents the second species with a complete sequenced and annotated mitochondrial genome (GenBank accession no. KM241869). The genome consists of circular chromosomes of 52,528u2009bp and encodes a total of 31 protein coding genes, 3 rRNAs and 26 tRNAs. The overall AT contents of the C. sorokiniana mtDNA is 70.89%, while the coding sequence is of 97.4%.

Mandibular hypoplasia, deafness, progeroid features and lipodystrophy (MDPL) syndrome in the context of inherited lipodystrophies

BACKGROUNDnLipodystrophies are a large heterogeneous group of genetic or acquired disorders characterized by generalized or partial fat loss, usually associated with metabolic complications such as diabetes mellitus, hypertriglyceridemia and hepatic steatosis. Many efforts have been made in the last years in identifying the genetic etiologies of several lipodystrophy forms, although some remain to be elucidated.nnnMETHODSnWe report here the clinical description of a woman with a rare severe lipodystrophic and progeroid syndrome associated with hypertriglyceridemia and diabetes whose genetic bases have been clarified through whole-exome sequencing (WES) analysis.nnnRESULTSnThis article reports the 5th MDPL (Mandibular hypoplasia, deafness, progeroid features, and lipodystrophy syndrome) patient with the same de novo p.S605del mutation in POLD1. We provided further genetic evidence that this is a disease-causing mutation along with a plausible molecular mechanism responsible for this recurring event. Moreover we overviewed the current classification of the inherited forms of lipodystrophy, along with their underlying molecular basis.nnnCONCLUSIONSnProgress in the identification of lipodystrophy genes will help in better understanding the role of the pathways involved in the complex physiology of fat. This will lead to new targets towards develop innovative therapeutic strategies for treating the disorder and its metabolic complications, as well as more common forms of adipose tissue redistribution as observed in the metabolic syndrome and type 2 diabetes.

KIR and their HLA Class I ligands: Two more pieces towards completing the puzzle of chronic rejection and graft loss in kidney transplantation

Background Kidney transplantation is a life-saving treatment for patients with end-stage renal disease. However, despite progress in surgical techniques and patient management, immunological rejection continues to have a negative impact on graft function and overall survival. Incompatibility between donors and recipients for human leukocyte antigens (HLA) of the major histocompatibility complex (MHC) generates a series of complex cellular and humoral immune response mechanisms that are largely responsible for rejection and loss of graft function. Within this context, a growing amount of evidence shows that alloreactive natural killer (NK) cells play a critical role in the immune response mechanisms elicited by the allograft. Killer immunoglobulin-like receptors (KIRs) are prominent mediators of NK cell alloreactivity. Methods and findings A cohort of 174 first cadaveric kidney allograft recipients and their donors were selected from a total cohort of 657 transplanted patients for retrospective immunogenetic analyses. Patients with HLA Class II mismatches were excluded. HLA Class I allele frequencies were compared among patients with chronic rejection, patients with stable graft function and a group of 2388 healthy controls. Activating and inhibitory KIR gene frequencies, KIR haplotypes, KIR-HLA ligand matches/mismatches and combinations of recipient KIRs and donor HLA Class I ligands were compared among patients with and without chronic rejection and a group of 221 healthy controls. Patients transplanted from donors homozygous for HLA-C1 antigens had a significantly higher risk for chronic rejection than patients transplanted from donors homozygous or heterozygous for HLA-C2 antigens or with epitopes belonging to the HLA-Bw4 ligand group. The Kaplan-Meier curves obtained by dividing the patients into 3 groups according to the presence or absence of one or both of the combinations of recipient KIRs and donor HLA ligands (rKIR2DL1/dHLA-C2 and rKIR3DL1/dHLA-Bw4) showed a significantly higher cumulative incidence of chronic rejection in the group of patients completely lacking these functional units. These patients showed a progressively stronger decline in modification of diet in renal disease-estimated glomerular filtration rate. Conclusions KIR genotyping should be performed at the time of enrolment of patients on the waiting list for organ transplantation. In our study, a significantly higher risk of chronic rejection after kidney transplantation was observed when recipient (r) and donor (d) pairs completely lacked the two functional rKIR-dHLA ligand combinations rKIR2DL1/dHLA-C2 and rKIR3DL1/dHLA-Bw4. This immunogenetic profile corresponds to low levels of NK cell inhibition. Therefore, patients with this high risk profile could benefit from immunosuppressive therapy aimed at reducing NK-cell cytotoxicity.

Complete sequence and characterization of mitochondrial and chloroplast genome of Chlorella variabilis NC64A

Abstract The complete nucleotide sequences of the mitochondrial (mtDNA) and chloroplast (cpDNA) genomes of Chlorella variabilis NC64A (Trebouxiophyceae) have been determined in this study (GenBank accession no. KP271968 and KP271969, respectively). The mt genome assembles as a circle of 78,500u2009bp and contains 62 genes, including 32 protein-coding, 27 tRNA and 3 rRNA genes. The overall GC content is 28.2%, while the coding sequence is 34%. The cp genome forms a circle of 124,793u2009bp, containing 114 genes, including 79 protein-coding, 32 tRNA and 3 rRNA genes. The overall GC content is 33,9%, while the coding sequence is 50%.

HLA-G molecules and clinical outcome in Chronic Myeloid Leukemia

The human leukocyte antigen-G (HLA-G) gene encodes a tolerogenic protein known to promote tumor immune-escape. We investigated HLA-G polymorphisms and soluble molecules (sHLA-G) in 68 chronic myeloid leukemia (CML) patients. Patients with G*01:01:01 or G*01:01:02 allele had higher value of sHLA-G compared to G*01:01:03 (109.2±39.5 vs 39.9±8.8 units/ml; p=0.03), and showed lower event free survival (EFS) (62.3% vs 90.0%; p=0.02). The G*01:01:03 allele was associated with higher rates and earlier achievement of deep molecular response (MR)4.5 (100% vs 65%, median of 8 vs 58 months, p=0.001). HLA-G alleles with higher secretion of sHLA-G seem associated with lower EFS, possibly because of an inhibitory effect on the immune system. Conversely, lower levels of sHLA-G promoted achievement of MR4.5, suggesting increased cooperation with immune system.

Population and individual effects of non-coding variants inform genetic risk factors

Identifying functional non-coding variants can enhance genome interpretation and inform novel genetic risk factors. We used whole genomes and peripheral white blood cell transcriptomes from 624 Sardinian individuals to identify non-coding variants that contribute to population, family, and individual differences in transcript abundance. We identified 21,183 independent expression quantitative trait loci (eQTLs) and 6,768 independent splicing quantitative trait loci (sQTLs) influencing 73 and 41% of all tested genes. When we compared Sardinian eQTLs to those previously identified in Europe, we identified differentiated eQTLs at genes involved in malarial resistance and multiple sclerosis, reflecting the long-term epidemiological history of the island’s population. Taking advantage of pedigree data for the population sample, we identify segregating patterns of outlier gene expression and allelic imbalance in 61 Sardinian trios. We identified 809 expression outliers (median z-score of 2.97) averaging 13.3 genes with outlier expression per individual. We then connected these outlier expression events to rare non-coding variants. Our results provide new insight into the effects of non-coding variants and their relationship to population history, traits and individual genetic risk.

Deep genomic analysis of the Chlorella sorokiniana SAG 211-8k chloroplast

Abstract The chloroplast genome contains information that is applicable in many scientific fields, such as plant systematics, phylogenetic reconstruction and biotechnology, because its features are highly conserved among species. To date, several complete green algal chloroplast genomes have been sequenced and assembled. In this study, the nucleotide sequence of the chloroplast genome (cpDNA) of Chlorella sorokiniana SAG 211-8k is reported and compared for the first time to the chloroplast genomes of 10 Chlorellaceae. The recently updated Chlorella sorokiniana cpDNA sequence, assembled as a circular map of 109u2009811 bp, encodes 113 genes. Similar to other Chlorella strains, this chloroplast genome does not show a quadripartite structure and lacks the large rRNA operon-encoding Inverted Repeat (IR). The Chlorella sorokiniana plastid encodes the tRNA(Ile)-lysidine synthetase (tilS), which is responsible for modifying the CAU anticodon of a unique tRNA. Gene ordering and clustering highlight the close relationships among Chlorella clade members and the preservation of crucial gene clusters in photosynthetic strains. The features of Chlorella sorokiniana presented here reinforce the monophyletic character of Chlorellaceae and provide important information that sheds light on chloroplast genome evolution among species of Chlorella.

Novel action of FOXL2 as mediator of Col1a2 gene autoregulation

FOXL2 belongs to the evolutionarily conserved forkhead box (FOX) superfamily and is a master transcription factor in a spectrum of developmental pathways, including ovarian and eyelid development and bone, cartilage and uterine maturation. To analyse its action, we searched for proteins that interact with FOXL2. We found that FOXL2 interacts with specific C-terminal propeptides of several fibrillary collagens. Because these propeptides can participate in feedback regulation of collagen biosynthesis, we inferred that FOXL2 could thereby affect the transcription of the cognate collagen genes. Focusing on COL1A2, we found that FOXL2 indeed affects collagen synthesis, by binding to a DNA response element located about 65Kb upstream of this gene. According to our hypothesis we found that in Foxl2(-/-) mouse ovaries, Col1a2 was elevated from birth to adulthood. The extracellular matrix (ECM) compartmentalizes the ovary during folliculogenesis, (with type I, type III and type IV collagens as primary components), and ECM composition changes during the reproductive lifespan. In Foxl2(-/-) mouse ovaries, in addition to up-regulation of Col1a2, Col3a1, Col4a1 and fibronectin were also upregulated, while laminin expression was reduced. Thus, by regulating levels of extracellular matrix components, FOXL2 may contribute to both ovarian histogenesis and the fibrosis attendant on depletion of the follicle reserve during reproductive aging and menopause.