Optimization of storage condition for maintaining long-term viability of nematophagous fungus Esteya vermicola as biocontrol agent against pinewood nematode.

The fungus, Esteya vermicola has been proposed as biocontrol agent against pine wilting disease caused by Bursaphelenchus xylophilus. In this study, we reported the effects of temperature and different additives on the viability and biocontrol efficacy of E. vermicola formulated by alginate-clay. The viability of the E. vermicola formulation was determined for six consecutive months at temperature ranged from -70 to 25 °C. The fresh conidia without any treatment were used as control. Under the optimal storage conditions with E. vermicola alginate-clay formulation, the results suggested that E. vermicola alginate-clay formulation with a long shelf life could be a non-vacuum-packed formulation that contains 2 % sodium alginate and 5 % clay at 4 °C. Three conidial formulations prepared with additives of 15 % glycerol, 0.5 % yeast extract and 0.5 % herbal extraction, respectively significantly improved the shelf life. In addition, these tested formulations retained the same biocontrol efficacy as the fresh conidial against pinewood nematode. This study provided a tractable and low-cost method to preserve the shelf life of E. vermicola.

Comparison between conidia and blastospores of Esteya vermicola, an endoparasitic fungus of the pinewood nematode, Bursaphelenchus xylophilus.

Esteya vermicola, an endoparasitic fungus of Bursaphelenchus xylophilus, the pinewood nematode (PWN), exhibits great potential as a biological control agent against this nematode. E. vermicola produces blastospores in liquid media and aerial conidia on solid media. The agent was mass-produced using two kinds of culture media: S (50 % wheat bran and 50 % pine wood powder), L (0.5 g wheat bran and 0.5 g pinewood powder in 200 ml of potato dextrose broth), and two controls: SC (potato dextrose agar), LC (potato dextrose broth). Yields, multiple stress tolerance, storage life, new generation conidial number, and PWN mortality rates of the spores were measured in each of these four media and compared. The spore yields, new generation conidial number, and nematode mortality rates of blastospores were higher than those of conidia. Nevertheless, the conidia had a higher germination rate than the blastospores during the storage process and multiple stress treatments. Considering the number of spores surviving from the process of the storage and multiple stress treatments per unit of mass media, the blastospores from L survived most. Comprehensive analysis indicates that the L culture medium is the most optimal medium for mass production relatively.

Compound K is able to ameliorate the impaired cognitive function and hippocampal neurogenesis following chemotherapy treatment.

Chemotherapy frequently results in neurocognitive deficits that include impaired learning and memory. Thus, it is important to prevent or ameliorate the persistence of cognitive impairment. Compound K was employed to examine the ameliorating effect on chronic treatment with cyclophosphamide. Eight week-old ICR mice were given 80 mg/kg cyclophosphamide, cyclophosphamide combined with compound K (2.5, 5 and 10 mg/kg) or saline injections once per week for 4 weeks. Passive avoidance test and Y maze were used to evaluate memory and learning ability. Immunohistochemical staining for progenitor cell and immature neurons was used to assess changes in neurogenesis. Compound K (10 mg/kg) is able to ameliorate the decrease of neurogenesis in the hippocampus caused by cyclophosphamide. These results suggest that compound K might be a potential strategy to ameliorate or repair the disrupted hippocampal neurogenesis induced by the side effect of chemotherapy agent.

[Effects of NaCl stress on leaf photosynthesis characteristics and free amino acid metabolism of Heyedysarum scoparium].

This paper studied the variations of leaf photosynthesis gas exchange, chlorophyll fluorescence, and free amino acid contents of Heyedysarum scoparium under the stress of different concentration NaCl, aimed to understand the effects of salt stress on the leaf physiological characteristics and free amino acid metabolism of the plant. Under mild salt stress, the photo-damage of the leaf photosystem II was avoided via the dissipation of excess excitation energy, and stomatal limitation was the main factor reducing the photosynthesis rate. With the increase of salt stress, the leaf photoprotection was not sufficient to avoid oxidative damage, and thus, the damage to photosystem II happened. Under the stress of 200 mmol NaCl x L(-1), non-stomatal limitation was the main factor responsible for the inhibition of photosynthesis. The accumulation and metabolism of major free amino acids in H. scoparium leaves varied under salt stress. Under mild salt stress, the major free amino acids such as proline, glutamate, aspartate, and alanine had a significant accumulation, but with the further increase of salt stress, the aspartate and alanine contents in H. scoparium leaves decreased, while the synthesis and accumulation of praline increased.