Future N deposition and precipitation changes will be beneficial for the growth of Haloxylon ammodendron in Gurbantunggut Desert, northwest China.

Evaluation of precipitation and nitrogen (N) deposition in desert ecosystems helps to elucidate the reaction of desert ecosystems to future environmental changes. An in-situ field experiment was established to examine the influence of a long-term enhanced precipitation and N deposition on the photosynthetic traits and physiological characteristics of Haloxylon ammodendron in the Gurbantunggut Desert, northwest China, throughout the growing season in 2014-2016. Results showed a significant interaction between precipitation and N applications. Increased precipitation and N deposition and their coupling could significantly improve photosynthetic capacity, alter the variability in amplitude of water potential and change the content of substances regulating osmotic pressure in H. ammodendron. According to the comprehensive evaluation of H. ammodendron's adaptability using six different water and N coupling models, a combination of a 30% increase in precipitation and a 30 kg N ha-1 yr-1 addition in nitrogen deposition, or the addition of N at a concentration of 60 kg N ha-1 yr-1 with natural precipitation were beneficial to H. ammodendron growth and development. Hence, changes in the future global environment can be anticipated to be beneficial to H. ammodendron growth.

[Meiotic recombination hotspots in eukaryotes].

Meiotic recombination may occur more frequently in some regions of the eukaryotic genome. These regions are referred to as meiotic recombination hotspot loci. Genetic studies in the yeast have revealed that these hotspots contain special sites for recombination initiation and result in heterogeneous distribution of recombination (along the chromosome length or across the genome). However, the data for recombination hotspot is so far limited to organisms such as fungi, maize and human. In the present paper, we listed several typical approaches to characterizing recombination hotspots in different organisms, summarizing current progress in mapping of the meiotic recombination hotspots and discussing the factors and mechanisms for activation of eukaryotic meiotic recombination. Some unresolved questions and future prospects were also discussed.