Terrigenous sediment-dominated reef platform infilling: an unexpected precursor to reef island formation and a test of the reef platform size–island age model in the Pacific

Low-lying coral reef islands are considered highly vulnerable to climate change, necessitating an improved understanding of when and why they form, and how the timing of formation varies within and among regions. Several testable models have been proposed that explain inter-regional variability as a function of sea-level history and, more recently, a reef platform size model has been proposed from the Maldives (central Indian Ocean) to explain intra-regional (intra-atoll) variability. Here we present chronostratigraphic data from Pipon Island, northern Great Barrier Reef (GBR), enabling us to test the applicability of existing regional island evolution models, and the platform size control hypothesis in a Pacific context. We show that reef platform infilling occurred rapidly (~4–5 mm yr⁻¹) under a “bucket-fill” type scenario. Unusually, this infilling was dominated by terrigenous sedimentation, with platform filling and subsequent reef flat formation complete by ~5000 calibrated years BP (cal BP). Reef flat exposure as sea levels slowly fell post highstand facilitated a shift towards intertidal and subaerial-dominated sedimentation. Our data suggest, however, a lag of ~1500 yr before island initiation (at ~3200 cal BP), i.e. later than that reported from smaller and more evolutionarily mature reef platforms in the region. Our data thus support: (1) the hypothesis that platform size acts to influence the timing of platform filling and subsequent island development at intra-regional scales; and (2) the hypothesis that the low wooded islands of the northern GBR conform to a model of island formation above an elevated reef flat under falling sea levels.

     

Selection and molecular characterization of imidazolinone resistant mutation-derived lines of Tritordeum HT621

Imidazolinone herbicides resistant varieties, induced by mutations at the AHAS gene (acetohydroxyacid synthase), have been developed in many crops. Hexaploid tritordeum (Tritordeum Asch. & Graebn.) is the amphiploid derived from the cross between Hordeum chilense (H^chH^ch) and durum wheat Triticum turgidum L. (Thell) (AABB). Tritordeums have the potential to become a new crop with high added-value for food or feed. Mutagenesis with EMS was conducted to obtain imidazolinone resistant lines derived of the tritordeum HT621. Eleven M₃ plants were selected after imidazolinone treatment and five descendants of two of these lines (HT621-M3R1-3 and HT621-M3R10-1) were analyzed at the molecular level. Partial sequences of the three homologous AHAS loci in genomes A, B, and H^ch were obtained as well as those of HT621. A partial sequence of the AHAS gene in Hordeum chilense is first described in this work, and the designation ahasL-H ^ch 1 is proposed. A single Ser-Asn₆₂₇ substitution at the AHAS locus in the B genome is responsible of resistance in both lines. We propose the name AhasL-B2 for this resistance allele. This is the first report of the selection of imidazolinone resistant lines of tritordeum and the molecular characterization of the mutation conferring this resistance.     

Methylated DNA/RNA in Body Fluids as Biomarkers for Lung Cancer

DNA/RNA methylation plays an important role in lung cancer initiation and progression. Liquid biopsy makes use of cells, nucleotides and proteins released from tumor cells into body fluids to help with cancer diagnosis and prognosis. Methylation of circulating tumor DNA (ctDNA) has gained increasing attention as biomarkers for lung cancer. Here we briefly introduce the biological basis and detection method of ctDNA methylation, and review various applications of methylated DNA in body fluids in lung cancer screening, diagnosis, prognosis, monitoring and treatment prediction. We also discuss the emerging role of RNA methylation as biomarkers for cancer.     

Genetic Admixture in the Culturally Unique Peranakan Chinese Population in Southeast Asia

The Peranakan Chinese are culturally unique descendants of immigrants from China who settled in the Malay Archipelago ∼300–500 years ago. Today, among large communities in Southeast Asia, the Peranakans have preserved Chinese traditions with strong influence from the local indigenous Malays. Yet, whether or to what extent genetic admixture co-occurred with the cultural mixture has been a topic of ongoing debate. We performed whole-genome sequencing (WGS) on 177 Singapore (SG) Peranakans and analyzed the data jointly with WGS data of Asian and European populations. We estimated that Peranakan Chinese inherited ∼5.62% (95% confidence interval [CI]: 4.76–6.49%) Malay ancestry, much higher than that in SG Chinese (1.08%, 0.65–1.51%), southern Chinese (0.86%, 0.50–1.23%), and northern Chinese (0.25%, 0.18–0.32%). A sex-biased admixture history, in which the Malay ancestry was contributed primarily by females, was supported by X chromosomal variants, and mitochondrial (MT) and Y haplogroups. Finally, we identified an ancient admixture event shared by Peranakan Chinese and SG Chinese ∼1,612 (95% CI: 1,345–1,923) years ago, coinciding with the settlement history of Han Chinese in southern China, apart from the recent admixture event with Malays unique to Peranakan Chinese ∼190 (159–213) years ago. These findings greatly advance our understanding of the dispersal history of Chinese and their interaction with indigenous populations in Southeast Asia.     

Isolation and identification of ethisolide as an antibiotic product from Penicillium capsulatum

Summary Ethisolide has been isolated from cultures of Penicillium capsulatum, and its structure determined by means of infrared, mass spectrometry, ¹H- and ¹³C nuclear magnetic resonance. Antibiotic activity against a number of microorganisms is reported. Correspondence to: J. Atienza     

A cytoplasmic male sterility (CMS) system in durum wheat

Cytoplasmic male sterility (CMS) systems are based in the incompatible interaction between nucleus and cytoplasm and are commonly used for hybrid seed production in many crop species. The msH1 CMS system in common wheat results from the incompatibility between the nuclear genome of wheat and the cytoplasm of Hordeum chilense. Fertility restoration of the CMS phenotype is associated with the addition of the short arm of chromosome 6H^ch from H. chilense. In this work, we attempt to transfer the msH1 system to durum wheat and to evaluate its potential as a new source of CMS for the production of hybrid durum wheat. For that purpose, an alloplasmic durum wheat line was developed by substituting wheat cytoplasm by that from H. chilense. This line was completely male sterile. Also, the double translocation T6H^chS·6DL was transferred from common wheat into durum wheat, to test its potential as a restorer line. Finally, the system was tested by using the double T6H^chS·6DL translocation in durum wheat as pollen donor for the alloplasmic male sterile line, which confirmed the fertility restoration ability of 6H^chS in durum wheat.     

Rat blood and brain amino acid pattern in short term experimental diabetes

Some serum and brain amino acid variations occurring in animals with short term streptozotocin-diabetes (24 h) are studied in this work. Diabetic animals showed an increase in serum of the three branched-chain amino acids as well as an increase in free tryptophan, besides a decrease in total serum tryptophan and in the tryptophan/competitor amino acids ratio. In brain, the three branched-chain amino acids increased, but there were no variation in whole brain tryptophan. Nevertheless, by studying levels of tryptophan in different brain regions, an increase in medulla-pons was recorded. This circumstance could be explained by the increase in free serum tryptophan levels, in agreement with several authors who assign this reason for brain tryptophan.     

Trophic ecology of Calanoides acutus in Gerlache Strait and Bellingshausen Sea waters (Antarctica, December 2002)

We measured ingestion rates of Calanoides acutus on different microbial components of the Gerlache Strait (GE) and Bellingshausen Sea (BE) waters during December 2002. At the time of the study the abundance of both zooplankton (42–133 ind m⁻³) and phytoplankton (0.76–1.5 µg chlorophyll a l⁻¹) were low, indicating that the spring phytoplankton bloom was still not fully developed. C. acutus showed high clearance rates along the study (up to 432 ml ind⁻¹ day⁻¹), selecting for large motile organisms such as ciliates and the dinoflagellate Gyrodinium spp., although their feeding impact was always <0.1% of the standing stock of any of their prey. The total daily rations were low (∼2% body carbon per day), mostly the result of phytoplankton consumption (except for station GE3 in which heterotrophic flagellates contributed to 73% of the diet), and barely enough to cover metabolic demands. Based on the relationship between oxygen (carbon) consumption and ammonia excretion (considered as indicative of the metabolic substrate) it seems that standard metabolic demands were supplied, apart from the diet, by the use of their own non-structural proteins, whereas the remaining reserve-lipids were used to produce eggs.