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.     

Influence of progesterone administration in early stage of development on morphometric parameters of the rat uterus

The aim of this study was to evaluate the effects of single injection of 0.5 mg progesterone in neonatal stage of development on morphometric parameters of the adult rat uterus. The results showed that there were no changes ofendometrial morphometry in respect to oestrous cycle in neonatal treated rats. Neonatal administration of progesterone decreased the myometrium thickness in oestrus and dioestrums owing to circular muscle layer, and disturbed sex steroids secretion during the oestrous cycle. These data suggest that neonatal administration progesterone reduces the endometrium sensitivity to sex steroids and produces the myometrium atrophy.     

Characteristics of Basic Parameters of the Hormonal Function of the Adrenal Cortex and Its Modification in Rat Ontogenesis

The stress-reactivity of the pituitary-adrenocortical system (PAS) as assessed by the dynamics of the blood corticosterone level changes was studied in rats administered with cortisol at different periods of their pre- and postnatal ontogenesis. The participation of the activation and deactivation mechanisms in this process was estimated by means of a mathematical modeling, using the basic parameters of hormonal wave. It is established that in the one-month old rat pups born from mothers injected with cortisol from the day 14 to 18 of pregnancy, the basal and stress-evoked PAS activity was not essentially changed, whereas the adult animals demonstrated a faster decrease of the stress-induced corticosterone level. Injection of cortisol at the early neonatal ontogenesis (1–5 day of life) decreased the basal and stress-induced corticosterone levels at the morning hours in one-month old rats, whereas in adult rats it increased the PAS stress-reactivity. Injection of cortisol in the late neonatal ontogenesis, i.e., during the period of formation of the sensory systems (opening of the ears, eyes, maximal motor activity) resulted predominantly in changing the time of completion of the stress-induced hormonal response that became longer than in control animals of the same age. With the aid of mathematical modeling, we have found that at the early neonatal period of development the hormonal exposure mainly increases the rate of PAS activation, whereas injection of glucocorticoids at the late neonatal period changes PAS regulation by a feedback mechanism, thus decreasing the rate of system inactivation and increasing the time of completion of PAS stress-induced reaction. It is concluded that the phenotypic reorganization of PAS stress-reactivity by exogenous corticosteroids depends on the time of their action on development of the excitatory and inhibitory mechanisms during the critical periods of their formation.     

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.

     

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.