Mediterranean winter rainfall in phase with African monsoons during the past 1.36 million years.

Mediterranean climates are characterized by strong seasonal contrasts between dry summers and wet winters. Changes in winter rainfall are critical for regional socioeconomic development, but are difficult to simulate accurately1 and reconstruct on Quaternary timescales. This is partly because regional hydroclimate records that cover multiple glacial-interglacial cycles2,3 with different orbital geometries, global ice volume and atmospheric greenhouse gas concentrations are scarce. Moreover, the underlying mechanisms of change and their persistence remain unexplored. Here we show that, over the past 1.36 million years, wet winters in the northcentral Mediterranean tend to occur with high contrasts in local, seasonal insolation and a vigorous African summer monsoon. Our proxy time series from Lake Ohrid on the Balkan Peninsula, together with a 784,000-year transient climate model hindcast, suggest that increased sea surface temperatures amplify local cyclone development and refuel North Atlantic low-pressure systems that enter the Mediterranean during phases of low continental ice volume and high concentrations of atmospheric greenhouse gases. A comparison with modern reanalysis data shows that current drivers of the amount of rainfall in the Mediterranean share some similarities to those that drive the reconstructed increases in precipitation. Our data cover multiple insolation maxima and are therefore an important benchmark for testing climate model performance.

Dehydroxylative radical N-glycosylation of heterocycles with 1-hydroxycarbohydrates enabled by copper metallaphotoredox catalysis.

N-Glycosylated heterocycles play important roles in biological systems and drug development. The synthesis of these compounds heavily relies on ionic N-glycosylation, which is usually constrained by factors such as labile glycosyl donors, precious metal catalysts, and stringent conditions. Herein, we report a dehydroxylative radical method for synthesizing N-glycosides by leveraging copper metallaphotoredox catalysis, in which stable and readily available 1-hydroxy carbohydrates are activated for direct N-glycosylation. Our method employs inexpensive photo- and copper- catalysts and can tolerate some extent of water. The reaction exhibits a broad substrate scope, encompassing 76 examples, and demonstrates high stereoselectivity, favoring 1,2-trans selectivity for furanoses and α-selectivity for pyranoses. It also exhibits high site-selectivity for substrates containing multiple N-atoms. The synthetic utility is showcased through the late-stage functionalization of bioactive compounds and pharmaceuticals like Olaparib, Axitinib, and Metaxalone. Mechanistic studies prove the presence of glycosyl radicals and the importance of copper metallaphotoredox catalysis.

Deep drilling reveals massive shifts in evolutionary dynamics after formation of ancient ecosystem.

The scarcity of high-resolution empirical data directly tracking diversity over time limits our understanding of speciation and extinction dynamics and the drivers of rate changes. Here, we analyze a continuous species-level fossil record of endemic diatoms from ancient Lake Ohrid, along with environmental and climate indicator time series since lake formation 1.36 million years (Ma) ago. We show that speciation and extinction rates nearly simultaneously decreased in the environmentally dynamic phase after ecosystem formation and stabilized after deep-water conditions established in Lake Ohrid. As the lake deepens, we also see a switch in the macroevolutionary trade-off, resulting in a transition from a volatile assemblage of short-lived endemic species to a stable community of long-lived species. Our results emphasize the importance of the interplay between environmental/climate change, ecosystem stability, and environmental limits to diversity for diversification processes. The study also provides a new understanding of evolutionary dynamics in long-lived ecosystems.

Genome-wide identification, characterization and expression analysis of the MITF gene in Yesso scallops (Patinopecten yessoensis) with different shell colors.

The microphthalmia-associated transcription factor (MITF) is the center of the regulator network of melanin synthesis in vertebrates. However, the role of MITF in shell color formation is poorly studied in mollusks. In the present study, an MITF gene, PyMITF, was first identified at the whole-genome level in Yesso scallop (Patinopecten yessoensis), an evolutionarily and economically important species, the shell color of which shows polymorphism. The PyMITF is a large gene spanning ~37 kb in the genome with 7 introns and 8 exons. A basic helix-loop-helix leucine zipper (bHLH-LZ) domain was detected in the PyMITF protein sequence, which can bind the canonical E-box sequence in the promoter region of the downstream genes. Phylogenetic analysis of the MITFs among vertebrates and invertebrates revealed that the molecular evolution of MITFs was consistent with the species taxonomy. Different expression levels of PyMITF were detected among different shell color strains, indicating the important role of PyMITF involved in shell pigmentation. Besides, PyMITF was expressed at a significantly higher level in the central mantle than that in the edge mantle, proving the participation of the central mantle in shell color formation in molecular level for the first time. The work provides valuable information for the molecular mechanism study of shell color formation.

Transcriptional changes in the Japanese scallop (Mizuhopecten yessoensis) shellinfested by Polydora provide insights into the molecular mechanism of shell formation and immunomodulation.

The Japanese scallop (Mizuhopecten yessoensis) is one of the most important aquaculture species in Asian countries; however, it has suffered severe infection by Polydora in northern China in recent years, causing great economic losses. The Polydora parasitizes the shell of scallops, badly destroying the shell's structure. To investigate the molecular response mechanism of M. yessoensis to Polydora infestion, a comprehensive and niche-targeted cDNA sequence database for diseased scallops was constructed. Additionally, the transcriptional changes in the edge mantle, central mantle and hemocytes, tissues directly related to the disease, were first described in this study. The results showed that genes involved in shell formation and immunomodulation were significantly differentially expressed due to the infestation. Different transcriptional changes existed between the two mantle regions, indicating the different molecular functions likely responsible for the formation of different shell layers. The differential expression of genes for immune recognition, signal transduction and pathogen elimination presented an integrated immune response process in scallops. Moreover, neuromodulation and glycometabolism involved in the regulation process with relevant function significantly enriched. The study provides valuable information for mechanism study of shell formation and immunomodulation in scallops.