Little is known about the factors affecting the relative influences of stochastic and deterministic processes that govern the assembly of microbial communities in successional soils. Here, we conducted a meta-analysis of bacterial communities using six different successional soil datasets distributed across different regions. Different relationships between pH and successional age across these datasets allowed us to separate the influences of successional age (i.e., time) from soil pH. We found that extreme acidic or alkaline pH conditions lead to assembly of phylogenetically more clustered bacterial communities through deterministic processes, whereas pH conditions close to neutral lead to phylogenetically less clustered bacterial communities with more stochasticity. We suggest that the influence of pH, rather than successional age, is the main driving force in producing trends in phylogenetic assembly of bacteria, and that pH also influences the relative balance of stochastic and deterministic processes along successional soils. Given that pH had a much stronger association with community assembly than did successional age, we evaluated whether the inferred influence of pH was maintained when studying globally distributed samples collected without regard for successional age. This dataset confirmed the strong influence of pH, suggesting that the influence of soil pH on community assembly processes occurs globally. Extreme pH conditions likely exert more stringent limits on survival and fitness, imposing strong selective pressures through ecological and evolutionary time. Taken together, these findings suggest that the degree to which stochastic vs. deterministic processes shape soil bacterial community assembly is a consequence of soil pH rather than successional age.

Background: Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic cholinergic transmission in the insect central nervous system. The insect nAChR is the molecular target of a class of insecticides, neonicotinoids. Like mammalian nAChRs, insect nAChRs are considered to be made up of five subunits, coded by homologous genes belonging to the same family. The nAChR subunit genes of Drosophila melanogaster, Apis mellifera and Anopheles gambiae have been cloned previously based on their genome sequences. The silkworm Bombyx mori is a model insect of Lepidoptera, among which are many agricultural pests. Identification and characterization of B. mori nAChR genes could provide valuable basic information for this important family of receptor genes and for the study of the molecular mechanisms of neonicotinoid action and resistance.

Large areas of rainforest in Asia have been converted to plantations, with uncertain effects on soil biodiversity. Using standard metagenetic methods, we compared the soil biota of bacteria, fungi, and nematodes at three rainforest sites in Malaysia with two rubber plantation sites with similar soils and geology. We predicted the following: (1) that the rubber sites would have a lower α- and β-diversity than the rainforest sites, due to the monospecific canopy cover and intensive management with herbicides, pesticides, and fertilizers, and (2) that due to differences in the physical and biotic environment associated with cultivation, there would be distinct communities of bacteria, fungi, and nematodes. However, regarding (1), the results showed no consistent difference in α- and β-diversity of bacteria, fungi, or nematodes between rainforest and rubber plantation sites. It appears that conversion of rainforest to rubber plantations does not necessarily result in a decrease in diversity of soil biota. It may be that heterogeneity associated with the cultivation regimen compensates for loss of biotically imposed heterogeneity of the original rainforest. Regarding (2), as predicted there were statistically significant differences in community composition between rainforest and rubber plantation for bacteria, fungi, and nematodes. These differences could be related to a range of factors including light level, litter fall composition, pH, C and N, selecting a distinct set of soil taxa, and it is possible that this in itself would affect long-term soil function.

miR-34a was identified as one of the downregulated microRNAs (miRNAs) in human lung cancer. However, the precise biological role of miR-34a in p53 deficient lung cancer cell lines remains largely elusive. In the present study, we aimed to identify the role of miR-34a in the regulation of lung cancer cell proliferation. Using quantitative RT-PCR analysis, we found that miR-34a was highly upregulated in the p53 wild-type A549 human lung cancer cell line when treated with the DNA damaging agent adriamycin (ADR), but not in the SBC-5 cells harboring mutated p53. Transient introduction of miR-34a into A549 and SBC-5 cell lines caused complete suppression of cell proliferation and induced the cell cycle arrested at the G(1) phase. When we knockdown the miR-34a downstream target--Sitr1--using the small-interfering RNA, there was also a cell growth inhibition in both cell lines though not as much as miR-34a did. Moreover, we demonstrated that pretransfection of miR-34a could increase the sensitivity of both lung cancer cell lines to cisplatin (DDP), and this could be reverted by the miR-34a inhibitor. Moreover, when cells pretreated with siR-Sirt1, they are more sensitive to DDP than the control pretreated cells as well. We thus hypothesize the miR-34a/Sirt1 cascade involved with p53-independent functions. Overall, in this study, we found the proliferation inhibition function of miR-34a in vitro in lung cancer cell lines is p53 independent, and also demonstrated the combination therapeutic potential of miR-34a and DDP in lung cancer cell lines.

No abstract

Radiation-induced gastrointestinal syndrome, including nausea, diarrhea and dehydration, contributes to morbidity and mortality after medical or industrial radiation exposure. No safe and effective radiation countermeasure has been approved for clinical therapy. In this study, we aimed to investigate the potential protective effects of seabuckthorn pulp and seed oils against radiation-induced acute intestinal injury. C57/BL6 mice were orally administered seabuckthorn pulp oil, seed oil and control olive oil once per day for 7 days before exposure to total-body X-ray irradiation of 7.5 Gy. Terminal deoxynucleotidyl transferase dUTP nick end labeling, quantitative real-time polymerase chain reaction and western blotting were used for the measurement of apoptotic cells and proteins, inflammation factors and mitogen-activated protein (MAP) kinases. Seabuckthorn oil pretreatment increased the post-radiation survival rate and reduced the damage area of the small intestine villi. Both the pulp and seed oil treatment significantly decreased the apoptotic cell numbers and cleaved caspase 3 expression. Seabuckthorn oil downregulated the mRNA level of inflammatory factors, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-8. Both the pulp and seed oils elevated the level of phosphorylated extracellular-signal-regulated kinase and reduced the levels of phosphorylated c-Jun N-terminal kinase and p38. Palmitoleic acid (PLA) and alpha linolenic acid (ALA) are the predominant components of pulp oil and seed oil, respectively. Pretreatment with PLA and ALA increased the post-radiation survival time. In conclusion, seabuckthorn pulp and seed oils protect against mouse intestinal injury from high-dose radiation by reducing cell apoptosis and inflammation. ALA and PLA are promising natural radiation countermeasure candidates.

A genetic analysis of parasitic ability in the soybean cyst nematode Heterodera glycines was performed. To identify and characterize genes involved in parasitism, we developed three highly inbred H. glycines lines, OP20, OP25 and OP50, for use as parents for controlled crosses. Through these crosses, we have identified genes in the inbred parents that control reproduction of the nematode on hosts that carry resistance genes. These genes, designated as ror-* for reproduction on a resistant host, segregate in a normal Mendelian fashion as independent loci. Host range tests of F1 generation progeny indicated that at least one parasitism gene in both the OP20 and OP50 lines for host PI 88788 was dominant. Parasitism genes in OP50 for hosts “Peking” and PI 90763 are recessive. Two types of single female descent populations, a single backcrossed BC1F2-derived and a double backcrossed BC2F1-derived, were established on the susceptible soybean cultivar “Lee 68.” Host range tests for parasitism in these lines demonstrated the presence of two independent genes in OP50, one for host PI 88788 designated ror-1 and one for host PI 90763 designated ror-2. OP20 carries two independent genes for parasitism on PI 88788, designated as alleles kr3 and kr4.