Effects of Reserve Capacity on Seismic Response of Concentrically Braced Frames by Considering Brace Failure.

In order to study the influence of brace failure on the seismic response of concentrically braced frames and the improvement of the residual structure's resistance to collapse due to reserve capacity, a series of concentrically braced frame prototypes with different story numbers is designed. A matrix of six finite-element concentrically braced-frame (CBF) models is established, which is varied by the number of stories and the level of reserve capacities. Accuracy of the numerical model is verified by comparing the responses of the shaking-table test of the concentrically braced frames, under 10 different working conditions. Then, a nonlinear time-history analysis, considering brace failure in one specified story, is carried out. The results show that the story-drift angle of the failure story as well as its adjacent stories increases greatly in the ideal pinned model. The above phenomenon is particularly serious, when the failure occurs at the top or bottom of the structure. With the reserve capacity brought by column continuity, and the semi-rigid rotation capacity of the beam-to-column and column-to-base connections are taken into consideration, the increase in story-drift angle caused by the brace failure is effectively reduced. However, the inherent reserve capacity has little influence on the dynamic characteristics of concentrically braced frames in the elastic stage.

Priming Galleria mellonella (Lepidoptera: Pyralidae) larvae with heat-killed bacterial cells induced an enhanced immune protection against Photorhabdus luminescens TT01 and the role of innate immunity in the process.

The current study investigated the characteristics and mechanism of the invertebrate immune priming using Galleria mellonella (L.) (Lepidoptera: Pyralidae) larvae (host) and Photorhabdus luminescens TT01 (pathogen) as a model. The following parameters of the G. mellonella larvae primed by hemocoel injection of heat-killed cells of TT01 or Bacillus thuringiensis HD-1 were determined at designated times after priming and then compared and analyzed systematically: mortality of the primed larvae against TT01 infection (immune protection level), hemocyte density, phagocytosis and encapsulation abilities ofhemocyte, and antibacterial activity of cell free hemolymph (major innate parameters). The results showed that 1) immune priming increased survival of the larvae against a lethal infection of TT01 and the levels and periods of protection correlated positively to the priming dose; 2) the changes on the levels of protection and the major innate parameters of the larvae primed with either TT01 or HD-1 followed a similar pattern of the convex curve, although the levels and the timing of changes differed significantly among the four innate immune parameters and between two priming bacteria; and 3) the immune protection level at a time after priming was correlated to the overall level of four innate immune parameters of the primed larvae. The current study demonstrated that the immune priming phenomenon of G. mellonella larvae has low level of specificity, and it was achieved mainly by the regulation on the quantity and activity of major innate immune parameters, such as hemocytes, antimicrobial peptides, and enzymes.

Next-generation sequencing-based transcriptome analysis of Helicoverpa armigera Larvae immune-primed with Photorhabdus luminescens TT01.

Although invertebrates are incapable of adaptive immunity, immunal reactions which are functionally similar to the adaptive immunity of vertebrates have been described in many studies of invertebrates including insects. The phenomenon was termed immune priming. In order to understand the molecular mechanism of immune priming, we employed Illumina/Solexa platform to investigate the transcriptional changes of the hemocytes and fat body of Helicoverpa armigera larvae immune-primed with the pathogenic bacteria Photorhabdus luminescens TT01. A total of 43.6 and 65.1 million clean reads with 4.4 and 6.5 gigabase sequence data were obtained from the TT01 (the immune-primed) and PBS (non-primed) cDNA libraries and assembled into 35,707 all-unigenes (non-redundant transcripts), which has a length varied from 201 to 16,947 bp and a N50 length of 1,997 bp. For 35,707 all-unigenes, 20,438 were functionally annotated and 2,494 were differentially expressed after immune priming. The differentially expressed genes (DEGs) are mainly related to immunity, detoxification, development and metabolism of the host insect. Analysis on the annotated immune related DEGs supported a hypothesis that we proposed previously: the immune priming phenomenon observed in H. armigera larvae was achieved by regulation of key innate immune elements. The transcriptome profiling data sets (especially the sequences of 1,022 unannotated DEGs) and the clues (such as those on immune-related signal and regulatory pathways) obtained from this study will facilitate immune-related novel gene discovery and provide valuable information for further exploring the molecular mechanism of immune priming of invertebrates. All these will increase our understanding of invertebrate immunity which may provide new approaches to control insect pests or prevent epidemic of infectious diseases in economic invertebrates in the future.

[Bacterial diversity of different successional stage forest soils in Dinghushan].

OBJECTIVE: The aim of the present study was to investigate the soil bacterial diversity of pine forest (PF), pine-broadleaf mixed forest (MF) and monsoon evergreen broadleaf forest (MEBF), the typical forest types that represent early, middle and late successional stage forests in Dinghushan, respectively. The results obtained will also provide information for further examination of the relationship between the soil bacterial diversity and ecological function of the forests. METHOD: Three total DNA samples were extracted directly from soil samples collected from PF, MF and MEBF, and then the 16S rDNA sequences were PCR amplified and the libraries were constructed, respectively. For each of the three libraries constructed, 150 positive clones were picked randomly and the inserted 16S rDNA were sequenced. The soil bacterial diversity of the forests was analyzed by Mothur based on the sequences obtained. RESULT: A total of 122, 118 and 120 valid 16S rDNA sequences were obtained from PF, MF and MEBF, which represented 70, 64 and 72 operational taxonomic units (OTUs, definition at a level of 97% similarity), respectively. Bacteria belonging to 8 phyla were identified. Among them, Acidobacteria accounted for 53.3%, 67.8% and 60%, while Proteobacteria took up 29.5%, 20.3% and 32.5% in PF, MF and MEBF, respectively. The other bacterial phyla identified each accounted for less than 10%. The bacterial community structure differed significantly at species level among three soil samples (P < 0.05) with the percentages of the shared OTUs between any two soil samples lower than 25%. MEBF had the highest Chao index (414.2), Shannon index (3.90) and the lowest Simpson dominance index (0.0249). CONCLUSION: The soil bacterial community structure differed significantly at species level among PF, MF and MEBF in Dinghushan, while they have a similar structure at phyla or class levels with Acidobacteria predominated followed by Proteobacteria.