Dew measurement and estimation of rain-fed jujube (Zizyphus jujube Mill) in a semi-arid loess hilly region of China

Dew is an important water source for plants in arid and semi-arid regions. However, information on dew is scarce in such regions. In this study, we explored dew formation, amount, and duration of rain-fed jujube（Zizyphus jujube Mill） trees in a semi-arid loess hilly region of China（i.e., Mizhi County）. The data included dew intensity and duration, relative humidity, temperature, and wind speed measured from 26 July to 23 October, 2012 and from 24 June to 17 October, 2013 using a micro-climate system（including dielectric leaf wetness sensors, VP-3 Relative Humidity/Temperature Sensor, High Resolution Rain Gauge, and Davis Cup Anemometer）. The results show that atmospheric conditions of relative humidity of 〉78% and dew point temperature of 1°C–3°C are significantly favorable to dew formation. Compared with the rainfall, dew was characterized by high frequency, strong stability, and long duration. Furthermore, heavy dew accounted for a large proportion of the total amount. The empirical models（i.e., relative humidity model（RH model） and dew point depression model（DPD model）） for daily dew duration estimation performed well at 15-min intervals, with low errors ranging between 1.29 and 1.60 h, respectively. But it should be noted that the models should be calibrated firstly by determining the optimal thresholds of relatively humidity for RH model and dew point depression for DPD model. For rain-fed jujube trees in the semi-arid loess hilly regions of China, the optimal threshold of relative humidity was 78%, and the optimal upper and lower thresholds of dew point depression were 1°C and 5°C, respectively. The study further demonstrates that dew is an important water resource that cannot be ignored for rain-fed jujube trees and may affect water balance at regional scales.

Molecular cloning of partial 14-3-3 genes in the marine sponge Hymeniacidon perleve and its role in differentiating infectious and non-infectious bacteria

Sponges （phylum Porifera） are the phylogenetically oldest metazoa and highly efficient filter feeders. In the marine ecosystem, they are unconditionally exposed to environmental stresses. Understanding the sponge-bacteria interaction is hence of both eco- logical and biological significance. This study investigated the specific interaction between the sponge Hymeniacidon perleve and the non-infectious bacteria, Escherichia coli and infectious bacteria, Vibrio spp. by measuring the 14-3-3 mRNA expression of H. perleve. Three partial cDNAs of 14-3-3 proteins and partial 18S RNA in H. perleve were cloned and sequenced. Using Re- verse-transcription real-time PCR, the 14-3-3 mRNA expression of H. perleve was examined when exposed to three common bacteria in aquatic water--E, coli and two Vibrio spp. for different time and dosages. H. perleve could efficiently remove E. coli from the water column without self-infection; however Vibrio at higher dosages infected H. perleve. When H. perleve was ex- posed to E. coli （1.1×10^7 CFU mL^-1）, V. anguillarum II （1.2×10^6 CFU mL^-1） and V. alginolyticus （3.6×10^5 CFU mL-1） for 6 h, the 14-3-3 mRNA expression in the V. anguillarum II and V. alginolyticus groups was down-regulated by 2.67- and 2.36-fold, respectively. The 14-3-3 mRNA expression in the E. coli group was not significantly different. However, no clear trend was ob- served on the 14-3-3 transcript levels of H. perleve in response to different doses of V. anguillarum II for different time. The re- sults demonstrated that infectious bacteria can be discriminated by 14-3-3 mRNA expression of sponge H. perleve.