Differences in PItotal of Quercus liaotungensis seedlings between provenance

The performance index of overall photochemistry (PItotal) is widely used in photosynthesis research, but the PItotal interspecies differences are unclear. To this end, seeds of Quercus liaotungensis from 10 geographical provenances were planted in two different climate types. Two years later, leaf relative chlorophyll content (SPAD) and chlorophyll a fluorescence transient of seedlings were measured. Meanwhile, the environmental factors of provenance location, including temperature, precipitation, solar radiation, wind speed, transpiration pressure, and soil properties, were retrieved to analyze the trends of PItotal among geographic provenance. The results showed that, in each climate type, there was no significant difference in SPAD and electron transfer status between PSII and PSI, but PItotal was significantly different among geographic provenances. The major internal causes of PItotal interspecies differences were the efficiency of electronic transfer to final PSI acceptor and the number of active reaction centers per leaf cross-section. The main external causes of PItotal interspecies differences were precipitation of the warmest quarter, solar radiation intensity in July, and annual precipitation of provenance location. PItotal had the highest correlation with precipitation of the warmest quarter of origin and could be fitted by the Sine function. The peak location and fluctuating trend of precipitation—PItotal fitted curve were different in two climate types, largely due to the difference of precipitation and upper soil conductivity in the two test sites. Utilizing the interspecific variation and trends of PItotal might be a good strategy to screen high and stable photosynthetic efficiency of Q. liaotungensis provenance.

Comparative characteristics of human betaherpesviruses 6A and 6B. A modern view on the problem

This review is devoted to the comparative characteristics of human herpesvirus 6A (HHV6A) and human herpesvirus 6B (HHV6B), taking into account their exogenous and endogenous (inherited chromosomally integrated) forms. The analysis of the literature data on the main interspecies differences and intraspecies features of these viruses in molecular-genetic, biological, epidemiological and clinical aspects has been consistently carried out. Modern views about HHV6A and HHV6B, including their unique inherited chromosomal-integrated form, are the basis for organizing a system of epidemiological surveillance of infections caused by these viruses, as well as developing standardized methodological approaches to differential diagnosis, treatment and specific prevention of a wide range of virus-associated diseases. The development of this direction requires a greater evidence base and intensification of joint efforts of the scientific and medical communities.

Single-cell RNA sequencing reveals species-specific time spans of cell cycle transitions in early oogenesis

Oogenesis is a highly regulated process and its basic cellular events are evolutionarily conserved. However, the time spans of oogenesis differ substantially among species. To explore these interspecies differences in oogenesis, we performed single-cell RNA-sequencing on mouse and monkey female germ cells and downloaded the single-cell RNA-sequencing data of human female germ cells. The cell cycle analyses indicate that the period and extent of cell cycle transitions are significantly different between the species. Moreover, hierarchical clustering of critical cell cycle genes and the interacting network of cell cycle regulators also exhibit distinguished patterns across species. We propose that differences in the regulation of cell cycle transitions may underlie female germ cell developmental allochrony between species. A better understanding of the cell cycle transition machinery will provide new insights into the interspecies differences in female germ cell developmental time spans.