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.

     

Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.     

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.     

Epithelial trafficking of Sonic hedgehog by megalin.

We present here evidence of in vivo epithelial endocytosis and trafficking of non-lipid-modified Sonic hedgehog (ShhN) when infused into rat efferent ducts via microinjection. Initially, exogenous ShhN is detected in endocytic vesicles and early endosomes located near the apical plasma membrane of non-ciliated cells. Within 30-60 min following infusion, ShhN can be detected in lysosomes and at basolateral regions of non-ciliated cells. Basolaterally, ShhN was observed along the extracellular surfaces of interdigitated plasma membranes of adjacent cells and in the extracellular compartment underlying the efferent duct epithelium. Uptake and subcellular trafficking of infused ShhN by non-ciliated cells could be blocked by either anti-megalin IgG or the megalin antagonist, RAP. Ciliated cells, which do not express megalin, displayed little if any apical internalization of ShhN even though they were found to express Patched-1. However, ShhN was found in coated pits of lateral plasma membranes of ciliated cells as well as in underlying endocytic vesicles. We conclude that megalin-mediated endocytosis of ShhN can occur in megalin-expressing epithelia in vivo, and that the internalized ShhN can be targeted to the lysosome or transcytosed in the plane of the epithelium or across the epithelium. These findings highlight the multiple mechanisms by which megalin may influence Shh morphogen gradients in vivo.     

Molecular characterization and identification of markers for toxic and non-toxic varieties of <Emphasis Type="Italic">Jatropha curcas</Emphasis> L. using RAPD,AFLP and SSR markers

Jatropha curcas L., a multipurpose shrub has acquired significant economic importance for its seed oil which can be converted to biodiesel, is emerging as an alternative to petro-diesel. The deoiled seed cake remains after oil extraction is toxic and cannot be used as a feed despite having best nutritional contents. No quantitative and qualitative differences were observed between toxic and non-toxic varieties of J. curcas except for phorbol esters content. Development of molecular marker will enable to differentiate non-toxic from toxic variety in a mixed population and also help in improvement of the species through marker assisted breeding programs. The present investigation was undertaken to characterize the toxic and non-toxic varieties at molecular level and to develop PCR based molecular markers for distinguishing non-toxic from toxic or vice versa. The polymorphic markers were successfully identified specific to non-toxic and toxic variety using RAPD and AFLP techniques. Totally 371 RAPD, 1,442 AFLP markers were analyzed and 56 (15.09%) RAPD, 238 (16.49%) AFLP markers were found specific to either of the varieties. Genetic similarity between non-toxic and toxic verity was found to be 0.92 by RAPD and 0.90 by AFLP fingerprinting. In the present study out of 12 microsatellite markers analyzed, seven markers were found polymorphic. Among these seven, jcms21 showed homozygous allele in the toxic variety. The study demonstrated that both RAPD and AFLP techniques were equally competitive in identifying polymorphic markers and differentiating both the varieties of J. curcas. Polymorphism of SSR markers prevailed between the varieties of J. curcas. These RAPD and AFLP identified markers will help in selective cultivation of specific variety and along with SSRs these markers can be exploited for further improvement of the species through breeding and Marker Assisted Selection (MAS).     

C-Dimethylated Flavones as Possible Potential Anti-Tubercular and Anticancer Agents.

The present investigation describes an intramolecular Oxa-Michael addition of penta-substituted phenols to the enone of the tether in the presence of iodine as the oxidizing agent. Ten C-Dimethylated flavones with moderate to good yields ( 10a – j , 60–89 %) were isolated by heating the corresponding C-dimethylated chalcones using iodine in DMSO. Using the Microplate Alamar Blue test (MABA) technique, the drugs′ quantitative drug susceptibility against the H37Rv strain of replicating Mycobacterium TB was determined. The sensitivity of two of the developed compounds ( 10e , 10h ) was up to 6.25 g/mL. The human lung adenocarcinoma cell lines (A549) were used in the anticancer study, which was carried out using the MTT cell proliferation assay. In A549 cell lines, four flavones demonstrated anticancer activity with IC₅₀ values between 39 and 48 μM. The C-dimethylated flavones, 10b (3,4-dimethoxy), 10c (2,3,4-trimethoxy), 10e (p-fluoro) and 10 g (N-methyl indole) substitutions on ring ‘B’ showed good anticancer activity with IC₅₀ values 39.17, 39.21, 48.43 and 43.48 μM, respectively. The compounds 10b , 10c , 10d , 10e , and 10i had improved binding and interaction profiles among all the compounds examined during the current In Silico research, as shown by the docking simulations against two targets EGFR and MTB MurI.     

Cross species amplification ability of novel microsatellites isolated from <Emphasis Type="Italic">Jatropha curcas</Emphasis> and genetic relationship with sister taxa

The present investigation was undertaken with an aim to check the ability of cross species amplification of microsatellite markers isolated from Jatropha curcas—a renewable source of biodiesel to deduce the generic relationship with its six sister taxa (J. glandulifera, J. gossypifolia, J. integerrima, J. multifida, J. podagrica, and J. tanjorensis). Out of the 49 markers checked 31 markers showed cross species amplification in all the species studied. JCDS-30, JCDS-69, JCDS-26, JCMS-13 and JCMS-21 amplified in J. curcas. However, these markers did not show any cross species amplification. Overall percentage of polymorphism (PP) among the species studied was 38% and the mean genetic similarity (GS) was found to be 0.86. The highest PP (24) and least GS (0.76) was found between J. curcas/J. podagrica and J. curcas/J. multifida and least PP (4.44) and highest GS (0.96) was found between J. integerrima/J. tanjorensis. Dendrogram analysis showed good congruence to RAPD and AFLP than nrDNA ITS data reported earlier. The characterized microsatellites will pave way for intraspecies molecular characterization which can be further utilized in species differentiation, molecular identification, characterization of interspecific hybrids, exploitation of genetic resource management and genetic improvement of the species through marker assisted breeding for economically important traits.     

Cartilage link protein 1 (Crtl1), an extracellular matrix component playing an important role in heart development

To expand our insight into cardiac development, a comparative DNA microarray analysis was performed using tissues from the atrioventricular junction (AVJ) and ventricular chambers of mouse hearts at embryonic day (ED) 10.5-11.0. This comparison revealed differential expression of approximately 200 genes, including cartilage link protein 1 (Crtl1). Crtl1 stabilizes the interaction between hyaluronan (HA) and versican, two extracellular matrix components essential for cardiac development. Immunohistochemical studies showed that, initially, Crtl1, versican, and HA are co-expressed in the endocardial lining of the heart, and in the endocardially derived mesenchyme of the AVJ and outflow tract (OFT). At later stages, this co-expression becomes restricted to discrete populations of endocardially derived mesenchyme. Histological analysis of the Crtl1-deficient mouse revealed a spectrum of cardiac malformations, including AV septal and myocardial defects, while expression studies showed a significant reduction in versican levels. Subsequent analysis of the hdf mouse, which carries an insertional mutation in the versican gene (CSPG2), demonstrated that haploinsufficient versican mice display septal defects resembling those seen in Crtl1(-/-) embryos, suggesting that reduced versican expression may contribute to a subset of the cardiac abnormalities observed in the Crtl1(-/-) mouse. Combined, these findings establish an important role for Crtl1 in heart development.