New insights into the role of acidocalcisomes in trypanosomatids.

Acidocalcisomes are electron-dense organelles rich in polyphosphate and inorganic and organic cations that are acidified by proton pumps, and possess several channels, pumps, and transporters. They are present in bacteria and eukaryotes and have been studied in greater detail in trypanosomatids. Biogenesis studies of trypanosomatid acidocalcisomes found that they share properties with lysosome-related organelles of animal cells. In addition to their described roles in autophagy, cation and phosphorus storage, osmoregulation, pH homeostasis, and pathogenesis, recent studies have defined the role of these organelles in phosphate utilization, calcium ion (Ca2+ ) signaling, and bioenergetics, and will be the main subject of this review.

Mining novel effector proteins from the esophageal gland cells of Meloidogyne incognita.

Meloidogyne incognita is one of the most economically damaging plant pathogens in agriculture and horticulture. Identifying and characterizing the effector proteins which M. incognita secretes into its host plants during infection is an important step toward finding new ways to manage this pest. In this study, we have identified the cDNAs for 18 putative effectors (i.e., proteins that have the potential to facilitate M. incognita parasitism of host plants). These putative effectors are secretory proteins that do not contain transmembrane domains and whose genes are specifically expressed in the secretory gland cells of the nematode, indicating that they are likely secreted from the nematode through its stylet. We have determined that, in the plant cells, these putative effectors are likely to localize to the cytoplasm. Furthermore, the transcripts of many of these novel effectors are specifically upregulated during different stages of the nematode's life cycle, indicating that they function at specific stages during M. incognita parasitism. The predicted proteins showed little to no homology to known proteins from free-living nematode species, suggesting that they evolved recently to support the parasitic lifestyle. On the other hand, several of the effectors are part of gene families within the M. incognita genome as well as that of M. hapla, which points to an important role that these putative effectors are playing in both parasites. With the discovery of these putative effectors, we have increased our knowledge of the effector repertoire utilized by root-knot nematodes to infect, feed on, and reproduce on their host plants. Future studies investigating the roles that these proteins play in planta will help mitigate the effects of this damaging pest.

[Pollution characteristics and evaluation of nitrogen, phosphorus and organic matter in surface sediments of Lake Changshouhu in Chongqing, China].

In order to reveal spatial distribution characteristics of nutrient in the surface sediments of Lake Changshouhu, contents of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) of 62 surface sediments samples were determined and compared with other urban (suburban) lakes in China. C/N and the correlation of TN, TP and OM had also been analyzed. The results showed that the average contents of TN and TP were 2 255.89 mg x kg(-1) and 622.03 mg x kg(-1) respectively. Nitrogen and phosphorus pollution were very serious all over the lake, with a significantly different spatial distribution. The average content of OM was 2.80%. So the contents of TN, TP and OM were in the middle level compared with other lakes. 87.10% of C/N was between 5 and 14 (72.58% within which was between 6 and 13) and 3.23% of C/N was between 2.8 and 3.4, which showed that OM came from algae, phytoplankton and zooplankton. Besides, a small part of OM came from aquatic organisms. OM and TN were significantly correlated (Pearson coefficient was 0.849), but with less significant correlation to TP. The spatial distribution characteristics of OM were very similar with that of TN. The content of OM in water samples collected from western and middle waterbody was higher than that in eastern waterbody, which was the same as TN. By evaluating pollution situation with organic index and organic nitrogen, the average organic index was 0.386 which was on the III level still belonged to clean category. However, the average number of organic nitrogen was up to 0.214% which was on the IV level indicated the pollution degree. This showed that the lake Changshouhu was in a serious pollution situation especially in nitrogen pollution.

[Influence of disturbance intensity on nitrogen, phosphorus and permanganate index release of Potamogeton crispus during soaking in water].

Influence of various disturbance intensities on nitrogen, phosphorus and permanganate index (PI) release of Potamogeton crispus were investigated during the plant soaking in water, and the plant materials were collected in an urban lake of Beijing. Results showed that more rapid release of TP and PI from Potamogeton crispus were caused by disturbance, NH4(+) -N and TN in water were significantly increased (ANOVA, p < 0.05) under the condition of high disturbance (120 r/min) for 240 h. However, PI and TP were significantly decreased (ANOVA, p < 0.05) after 240 h disturbance in all treatments. When the release equilibrium of 2.13 g dry mass Potamogeton crispus in one liter of water was reached, the PI, TN, and TP released from unit mass Potamogeton crispus were 35, 5.1 and 4.1 mg x g(-1), respectively. The release ratio of TP from Potamogeton crispus was the highest, while the release ratio of PI was the lowest. The simulated experiment results showed that the highest pollution load to water released from Potamogeton crispus was the TP among the three nutrients. Phosphorus is one of the key factors which causing water eutrophication in lake, thus after submerged plants declining in lake, the field research of phosphorus release and migration from submerged plants into water is the focus of future research work.