The effect of SARS-CoV-2 infection on human embryo early development:a multicenter prospective cohort study

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARSCo V-2)infection has swept the globe for 3 years(Zhou et al.,2020).With the nationwide relaxation of controls on the coronavirus disease 2019(COVID-19)epidemic since December 2022 in China,fertility and in vitro fertilization(IVF)centers are receiving increasing numbers of infected patients.

Centennial-scale monsoon collapses during Marine Isotope Stage(MIS)7e detected in a northern Chinese stalagmite record

Occurrence or absence of centennial-scale climatic variability during Marine Isotope Stage(MIS)7e,the first peak interval of the Penultimate Interglacial,remains ambiguous due to the limited available high-resolved records.Here,we present a decadal-resolved stalagmiteδ^(18)O record from northern China spanning from 242.3 to 236.8 ka BP,covering MIS7e.The composite KLSδ^(18)O record,integrating this study with the previous record in the same cave,shows a descending trend from TerminationⅢto MIS7e,which follows the increasing Northern Hemisphere summer insolation(NHSI).This observation further emphasizes the important influence of NHSI on the glacial/interglacial transition.There are more large-amplitude,millennial-to centennial-scale variability occurring during TerminationⅢcompared with MIS7e,implying that ice-sheet decay potentially plays an important role in climatic excursions.Four centennial-scale summer monsoon collapses,peaking at~242.1,~240.8,~239.3 and~238.2 ka BP,are detected in our new record,indicating the pervasiveness of the intra-interglacial climatic instability.Given the lack of solar activity and freshwater outbursts data during MIS7e,it is not possible to conclude about the drivers of the identified abrupt climatic anomalous.Following the dynamic mechanisms of sub-millennial climatic anomalous during early Holocene,we tentatively propose that slowdown of the meridional overturning circulation caused by freshwater fluxes into North Atlantic and/or attenuated solar irradiance is the potential forcing for the abrupt climate events within MIS7e.Additionally,attenuated solar irradiance could also result in climatic anomalies through low-latitude processes.

Spatiotemporal evolution of C3/C4 vegetation and its controlling factors in southern China since the last glacial maximum

To date, few research have been reported on the evolution of C3/C4 vegetation in southern China, and the main mechanism influencing the evolution of C3/C4 vegetation is unclear. That makes it difficult for researchers to understand the competition mechanism of C3 and C4 plants under different climate environments and its relationship with the climate factors. It is also not conducive for researchers to assess the influence of future climate change on regional C3/C4 vegetation. Exactly, C3/C4 vegetation change in the regional-scale will have a significant impact on the global carbon cycle and agricultural production.Therefore, it is especially important to reconstruct the evolutionary history of C3/C4 vegetation in southern China and clarify the influencing mechanism of climate change. In this study, we systematically analyzed stable carbon isotope(δ13 C) of the longchain n-alkanes in sediment samples from eight lakes and four peat profiles in southern China, to reconstruct the spatiotemporal evolution of C3/C4 vegetation in these regions since the Last Glacial Maximum(LGM) and to investigate the climate factors that affect the C4 plant abundance change in the research area. The integrated long-chain n-alkane(C27–C33) stable carbon isotope results of samples from Zhanjiang Huguangyan Maar Lake, Xingyun Lake, Lugu Lake and Dingnan peat showed that, from the LGM to the Early Holocene, C4 plant relative abundance exhibited a gradually increasing trend from 21% to 34%. In the Middle Holocene, the C4 plant abundance significantly declined and reached a lowest value of 10%. In space, the C4 plant abundance generally exhibited a gradually declining trend from south to north in the LGM and the Early Holocene, while it showed an opposite trend in the Holocene Climate Optimum(6.0 cal ka BP). It reflected that the main influencing factor on C4 plants spatial distribution was changing from temperature to precipitation. This study indicated that temperature was the dominant factor affecting C4 plant distribution in southern China, however, when the temperature condition was appropriate, an increase in precipitation(especially more spring precipitation) would reduce the competitive advantages of C4 plants. Therefore, the combination of temperature and seasonal precipitation was the important factor that determines the C3/C4 vegetation proportion change in the southern China. Under the premise that the temperature will rise and precipitation will increase in the future, the reduction of a competitive advantage for the C4 plants could affect agricultural production in China.

Perinatal outcome and postnatal health in children born from cryopreserved embryos

Frozen-thawed embryo transfer(FET)has been increasingly adopted as an adjunct to in vitro fertilization or intracytoplasmic sperm injection in recent years.It can reduce the risks of ovarian hyperstimulation syndrome and multiple pregnancies,and may even improve pregnancy outcomes in some subgroups such as patients with polycystic ovary syndrome.However,embryo cryopreservation may cause DNA damage,epigenetic changes,and alterations to gene expression profiles,and the potential impacts of cryopreservation on the embryos and on the long-term health of the resulting offspring are receiving increasing attention.Here,we aim to summarize the impact of cryopreservation on the embryos,perinatal outcomes,and long-term health of the offspring,hoping to explore the potential mechanisms and help guide the next steps in designing clinical studies.In this review,we found that there was no apparent difference in most perinatal outcomes between neonates born following FET and fresh embryo transfer,except for higher risks of large-for-gestational age and macrosomia in FET neonates.Studies on the long-term health and development of FET children are currently lacking;however,the limited evidence so far has found no risk of growth retardation,or chronic or malignant diseases.Large,well-designed,prospective studies taking full consideration of the confounding factors,including parental information,lifestyle,and environmental factors,are needed to confirm these conclusions.