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.     

Social inequalities and mortality in europe - results from a large multi-national cohort

Background

Socio-economic inequalities in mortality are observed at the country level in both North America and Europe. The purpose of this work is to investigate the contribution of specific risk factors to social inequalities in cause-specific mortality using a large multi-country cohort of Europeans.

Methods

A total of 3,456,689 person/years follow-up of the European Prospective Investigation into Cancer and Nutrition (EPIC) was analysed. Educational level of subjects coming from 9 European countries was recorded as proxy for socio-economic status (SES). Cox proportional hazard model''s with a step-wise inclusion of explanatory variables were used to explore the association between SES and mortality; a Relative Index of Inequality (RII) was calculated as measure of relative inequality.

Results

Total mortality among men with the highest education level is reduced by 43% compared to men with the lowest (HR 0.57, 95% C.I. 0.52–0.61); among women by 29% (HR 0.71, 95% C.I. 0.64–0.78). The risk reduction was attenuated by 7% in men and 3% in women by the introduction of smoking and to a lesser extent (2% in men and 3% in women) by introducing body mass index and additional explanatory variables (alcohol consumption, leisure physical activity, fruit and vegetable intake) (3% in men and 5% in women). Social inequalities were highly statistically significant for all causes of death examined in men. In women, social inequalities were less strong, but statistically significant for all causes of death except for cancer-related mortality and injuries.

Discussion

In this European study, substantial social inequalities in mortality among European men and women which cannot be fully explained away by accounting for known common risk factors for chronic diseases are reported.     

Inhibition of [3H]captopril binding by peptide analog angiotensin converting enzyme inhibitors

Ketomethylene containing peptide analogs, modeled after a snake venom pentapeptide, have been shown to be potent angiotensin converting enzyme inhibitors. Although the most potent compounds are up to five times more potent than captopril in inhibiting angiotensin converting enzyme activity, they are relatively weak inhibitors of [3H]captopril binding to membrane bound angiotensin converting enzyme. This indicates that inhibition of [3H]captopril binding and enzymatic activity is due to binding to distinct sites. These results suggest that the inhibitors bind to an additional site on the enzyme distinct from the captopril binding site.     

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.

     

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.     

Dynamics of submersed aquatic vegetation on shallow soft bottoms in the Baltic Sea

Abstract. Persistence and colonization of submersed aquatic plant species were studied in permanent plots (20 cm × 20 cm) at three shallow sites adjacent to Askö island, in the northern Baltic Sea. The study started in 1991 at two of the sites, in 1992 at a third site and continued until 1997. Two major weather‐induced disturbances occurred during the study: a long, stormy period during a mild winter and a cold winter with extreme low water levels. The stormy period caused a large loss of species from plots (95 ± 5% SE) at the most wave‐exposed site, resulting in a low species number per plot (0.8 ± 0.2) the following summer. During the three following years the mean species number increased to 3.6 ± 0.2. The cold winter caused high species turnover and increased species number per plot at the two most wave‐exposed sites. The species turnover at the sheltered site was highest in the two years with low water level in May, possibly due to increased waterfowl herbivory. Annuals, loosely anchored and highly reproductive species had significantly higher plot colonization rates and lower persistence than perennials, well‐anchored species and species with none or low reproduction. The extent of lateral growth had no significant effect on colonization or persistence. Although these disturbances have a large effect on the dynamics, species mobility was also high in other years. Relative to other, similar, studies in terrestrial vegetation mean persistence in plots was remarkably low and mean mobility and species turnover rates were very high.     

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.     

Absorption, metabolism, and excretion studies of carbon 14- and tritium-labeled derivatives of a ketomethylene containing tripeptide

Tritium and Carbon 14 analogs of the angiotensin converting enzyme inhibitor ketoACE were synthesized and their oral absorption, metabolism and excretion in rats were investigated. KetoACE, a ketomethylene analog of the tripeptide Bz-Phe-Gly-Pro, was slowly absorbed at a 35% level upon oral administration. It is rapidly eliminated from the blood with a half-life of about 10 minutes. Its excretion is primarily via the bile duct and it is excreted as 80% unchanged drug. The only identified metabolite consisting of 5-10% of the excreted radioactivity was determined to be the reduced ketoACE in which the ketone group was reduced to a hydroxyl.     

An active puromycin analog derived from a non-nephrotoxic aminonucleoside

Replacement of the 5'-OH group of puromycin aminonucleoside (PAN) with H resulted in the elimination of kidney toxicity associated with administration of PAN. Thus, 5'-deoxy-PAN was not nephrotoxic to rats under the usual criteria. The corresponding 5'-deoxypuromycin derived from 5'-deoxy-PAN was examined in a ribosomal peptidyl transferase assay and was found to be an excellent substrate for the transpeptidation reaction with bacterial ribosomes; the Km was 0.29 mM compared to the Km for puromycin of 0.20 mM. Thus, a puromycin analog has been prepared which retains puromycin-like activity at the ribosomal level, but which is capable of releasing only a non-nephrotoxic aminonucleoside by enzymatic hydrolysis of the $\text{p}$-methoxyphenylalanyl side-chain.