适用于鼠学习记忆行为训练的三个新模型

目的检测模拟自然生活状态下大鼠的学习记忆行为。方法：自制微机控制的多功能训练系统,设计训练模型,即指定通过、交替选择和择洞逃避。结果：三个新模型能较好地检测大鼠日常生活有关学习记忆行为。结论：模型具备客观、形象直观和省时的特点     

Can Biochar and Phytoextractors Be Jointly Used for Cadmium Remediation?

Phytoremediation of soils contaminated with cadmium was tested after liming (CaO) or biochar addition, using red amaranth (Amaranthus tricolor L.) as test plant species. Two biochars with contrasting characteristics were prepared from two feedstocks and added to the soil at a rate of 3% (w:w): Eucalyptus pyrolysed at 600°C (EB) and poultry litter at 400°C (PLB). Liming was carried out in two treatments (CaO1) and (CaO2) to the same pH as the treatments EB and PLB respectively. Total plant mass increased in soils amended with PLB and with a mixture of PLB and EB; however this was not sufficient to increase the efficiency of phytoextraction. Bioavailable and mobile fractions of Cd diminished after liming or biochar addition. Our study infers that, both the amount of Cd immobilized and the main mechanism responsible for this immobilization varies according to biochar properties.     

The Abi Proteins and Their Involvement in Bacteriocin Self-Immunity

The Abi protein family consists of putative membrane-bound metalloproteases. While they are involved in membrane anchoring of proteins in eukaryotes, little is known about their function in prokaryotes. In some known bacteriocin loci, Abi genes have been found downstream of bacteriocin structural genes (e.g., pln locus from Lactobacillus plantarum and sag locus from Streptococcus pyogenes), where they probably are involved in self-immunity. By modifying the profile hidden Markov model used to select Abi proteins in the Pfam protein family database, we show that this family is larger than presently recognized. Using bacteriocin-associated Abi genes as a means to search for novel bacteriocins in sequenced genomes, seven new bacteriocin-like loci were identified in Gram-positive bacteria. One such locus, from Lactobacillus sakei 23K, was selected for further experimental study, and it was confirmed that the bacteriocin-like genes (skkAB) exhibited antimicrobial activity when expressed in a heterologous host and that the associated Abi gene (skkI) conferred immunity against the cognate bacteriocin. Similar investigation of the Abi gene plnI and the Abi-like gene plnL from L. plantarum also confirmed their involvement in immunity to their cognate bacteriocins (PlnEF and PlnJK, respectively). Interestingly, the immunity genes from these three systems conferred a high degree of cross-immunity against each other''s bacteriocins, suggesting the recognition of a common receptor. Site-directed mutagenesis demonstrated that the conserved motifs constituting the putative proteolytic active site of the Abi proteins are essential for the immunity function of SkkI, and to our knowledge, this represents a new concept in self-immunity.Bacteriocins are ribosomally synthesized antimicrobial peptides and proteins produced by a wide variety of bacterial genera. The majority of bacteriocins from Gram-positive bacteria are classified into two groups: the class I lantibiotics, containing posttranslationally modified peptides with ring-forming lanthionine or methyllanthionine residues, and the nonmodified class II peptide bacteriocins (8, 33, 34). Class II bacteriocins are further subdivided into pediocin-like bacteriocins (class IIa), two-peptide bacteriocins (class IIb), and nonpediocin one-peptide bacteriocins (class IIc) (33). Bacteriocin-producing bacteria normally possess a mechanism of immunity to protect themselves from their own bacteriocins, and such self-immunity is often mediated by a dedicated protein (32). For a few bacteriocin systems, the mechanisms by which these proteins confer immunity have been elucidated. For instance, immunity to the lantibiotic nisin (class I) involves a combined action which includes (i) sequestering of bacteriocins on the bacterial cell membrane by a protein called NisI and (ii) removal of the bacteriocins from cells by a dedicated ABC transporter (NisFEG) (39, 44). On the other hand, proteins conferring immunity to pediocin-like bacteriocins (class IIa) as well as lactococcins A and B (class IIc) have been shown to bind directly to the bacteriocin receptor and thereby inhibit pore formation (13). Hitherto, no immunity mechanism is known for any class IIb two-peptide bacteriocins.Recently, we reported that several bacteriocin loci encode proteins belonging to the Pfam Abi protein family (Pfam accession no. PF02517) (14). These loci include the plantaricin (pln) locus of Lactobacillus plantarum, encoding two two-peptide bacteriocins (12), the multibacteriocin pnc locus of Streptococcus pneumoniae (25), and the streptolysin S (sag) locus found in group A streptococci (35) (Fig. ​(Fig.1A).1A). Some of the Abi proteins encoded in these loci (PlnI in L. plantarum, PncO in S. pneumoniae, and SagE in Streptococcus pyogenes) are probable bacteriocin self-immunity proteins on the basis of gene knockout studies (10, 25) and genetic organization (i.e., being closely associated with bacteriocin structural genes), while others (e.g., PlnP and PlnTUVW in L. plantarum and PncP in S. pneumoniae) have completely unknown functions.Open in a separate windowFIG. 1.Abi-associated bacteriocin and bacteriocin-like loci. (A) Three known bacteriocin loci containing Abi genes, including the pln locus of L. plantarum (14), the pnc locus of S. pneumoniae (25), and the sag locus of S. pyogenes (10). (B) Seven potential new bacteriocin loci identified by genome mining for bacteriocin-associated Abi genes. Abi genes are shown as black arrows, bacteriocin structural genes are shown in red, ABC transporter genes are shown in blue, regulatory genes are shown in green, and other genes are shown in white. Gene names or locus tags are shown below the arrows. The genes are drawn approximately to scale. The boxed arrows in the L. sakei 23K genome represent a disrupted histidine protein kinase gene.The Abi family, also known as the CAAX amino-terminal protease family, consists of putative membrane-bound metalloproteases from both eukaryotes and prokaryotes (38), with the majority being bacterial proteins (90%). The Abi family is recognized by three highly conserved motifs (38): motif 1, consisting of two neighboring and invariant glutamate residues and a conserved arginine separated by three residues (EEXXXR, where X denotes any amino acid); motif 2, consisting of a conserved phenylalanine and a conserved histidine separated by three residues (FXXXH); and motif 3, with an invariant histidine. The three conserved motifs are thought to constitute the active site of the Abi protease, and their importance in proteolytic activity has been demonstrated by mutational analysis of the yeast Abi protease RCE1 (15). In eukaryotic cells, Abi family proteins are involved in membrane targeting of proteins harboring the C-terminal sequence CAAX (C, cysteine; A, aliphatic amino acid; and X, any amino acid) via a process known as prenylation, which consists of the following three sequential reactions (23): (i) a geranylgeranyltransferase/farnesyltransferase attaches a prenyl group (lipid anchor) to the cysteine in the fourth-to-last position, (ii) a CAAX protease of the Abi family cleaves off the three C-terminal amino acids (-AAX), and (iii) an isoprenylcysteine carboxyl methyltransferase then attaches a methyl group to the C-terminal cysteine.Despite being widespread in prokaryotic genomes, the function of Abi proteins has not been investigated much in bacteria, with the exception of gene knockout experiments on the Abi genes sagE and pncO, which implies their involvement in bacteriocin self-immunity in streptococci (10, 25). Another Abi-like gene, prsW in Bacillus subtilis, has been studied to some extent (16). PrsW does not belong to any Pfam family but contains the same three motifs as the Abi proteins, with the exception of the conserved histidine in motif 2, which has been replaced by a glutamate in this protein. PrsW is a protease involved in response to antimicrobial peptides via a process known as regulated intracellular proteolysis (16). In this process, PrsW together with another protease (YluC) cleaves an anti-σ factor (RsiW) to release σ^W, which subsequently regulates gene expression in a manner that protects the cells from antimicrobial peptides. However, the PrsW target protein RsiW in B. subtilis does not harbor the C-terminal consensus sequence CAAX found for Abi target proteins in eukaryotes.Pfam (http://pfam.sanger.ac.uk/) is a comprehensive collection of protein families and domains. For each protein family in Pfam, a profile hidden Markov model (profile HMM) is built from an alignment of sequences from nonredundant representatives of the family (seed sequences), and this profile HMM is then used in an iterative fashion to find new members of the protein family (18, 43). The Abi family in Pfam contains a large number of sequences (1,966 by September 2009). However, several proteins containing Abi or Abi-like motifs are somehow not detected by the current search tool. Examples of this include PrsW from B. subtilis and PlnL from L. plantarum, which apparently contain all three motifs but somehow do not fit into Pfam''s Abi family. These observations suggest that the profile HMM for Abi may be based upon a slightly skewed sample of seed sequences, resulting in a low sensitivity. We provide here an updated profile HMM to detect Abi-like proteins in prokaryotes that are omitted in the present protein family. Furthermore, searches for novel Abi-associated bacteriocin loci were also performed in silico. Several potentially novel bacteriocin loci were identified, and one of them was assessed further by experimentation. The role of bacteriocin-associated Abi genes in self-immunity was also addressed by heterologous expression and site-directed mutagenesis.     

Biomass Accumulation and Carbon Sequestration in Four Different Aged Casuarina equisetifolia Coastal Shelterbelt Plantations in South China

Thousands of kilometers of shelterbelt plantations of Casuarina equisetifolia have been planted to protect the southeast coastline of China. These plantations also play an important role in the regional carbon (C) cycling. In this study, we examined plant biomass increment and C accumulation in four different aged C. equisetifolia plantations in sandy beaches in South China. The C accumulated in the C. equisetifolia plant biomass increased markedly with stand age. The annual rate of C accumulation in the C. equisetifolia plant biomass during 0–3, 3–6, 6–13 and 13–18 years stage was 2.9, 8.2, 4.2 and 1.0 Mg C ha⁻¹ yr⁻¹, respectively. Soil organic C (SOC) at the top 1 m soil layer in these plantations was 17.74, 5.14, 6.93, and 11.87 Mg C ha⁻¹, respectively, with SOC density decreasing with increasing soil depth. Total C storage in the plantation ecosystem averaged 26.57, 38.50, 69.78, and 79.79 Mg C ha⁻¹ in the 3, 6, 13 and 18- yrs plantation, with most of the C accumulated in the aboveground biomass rather than in the belowground root biomass and soil organic C. Though our results suggest that C. equisetifolia plantations have the characteristics of fast growth, high biomass accumulation, and the potential of high C sequestration despite planting in poor soil conditions, the interactive effects of soil condition, natural disturbance, and human policies on the ecosystem health of the plantation need to be further studied to fully realize the ecological and social benefits of the C equisetifolia shelterbelt forests in South China.     

棉花miR397 LAC4模块调控棉铃虫抗性研究

miRNA(microRNA)通过调控其靶标基因在植物的生长、发育和抗逆过程中扮演着重要的角色。该研究采用分子生物学和生物化学等方法,探讨棉花miR397 LAC4参与植株木质素生物合成和对棉铃虫抗性响应机制。结果发现：(1)棉花miR397(ghr miR397)在转录后调控漆酶基因(GhLAC4)的表达,GhLAC4属于蓝铜氧化酶家族,通过调控木质素合成,抵御棉铃虫入侵棉花。(2)GUS报告基因融合表达和酶活性测定表明,ghr miR397在转录后切割靶标基因GhLAC4抑制其表达。(3)利用VIGS(virus induced gene silencing)技术在棉花中沉默和过表达ghr miR397,棉铃虫抗性检测分析表明,沉默miR397表达会增加棉花对棉铃虫的抗性,但过表达ghr miR397则会降低棉花的抗性。(4)选择性和非选择性棉铃虫实验分析、组织化学染色和木质素含量测定表明,沉默GhLAC4表达会减少木质素的积累,增加棉花对棉铃虫的敏感性。研究表明,ghr miR397 GhLAC4模块共同微调棉花木质素合成来参与棉花抗虫性调控,同时也为棉花抗虫育种提供了新思路。     

不同产地浙贝母生物碱含量及其合成相关基因表达研究

为了探究浙贝母(Fritillaria thunbergii)药效成分积累量与生物碱合成相关基因表达水平之间的关系,该研究采用UPLC-MS、qPCR技术分别测定不同产地11个样品中总生物碱(贝母素甲和贝母素乙之和)含量和3个参与生物碱合成途径相关基因(HMGR、FPS和DXR)的表达量,同时运用生物统计学方法分析成熟期鳞茎生物碱含量与各基因表达量之间的相关性。结果表明:不同产地浙贝母成熟期鳞茎总生物碱含量存在显著差异(P<0.05),为0.2105% ～ 0.4612%; HMGR和FPS基因在盛花期组织表达、盛花期至成熟期鳞茎表达变化趋势同生物碱含量变化趋势基本一致; DXR基因在成熟期鳞茎中表达量最高,盛花期组织表达、盛花期至成熟期鳞茎表达变化趋势同生物碱含量变化趋势大体不一致; HMGR、FPS基因表达量分别与贝母素甲、贝母素乙和总生物碱含量呈显著或极显著正相关性(P<0.05或P<0.01),以FPS基因表达量与生物碱含量相关系数为最高,相关系数分别为0.672,0.631,0.664,DXR基因与生物碱含量呈低度相关性。由此可以推断,生物碱的积累受MVA途径中HMGR、FPS基因协同调控或者修饰作用明显,受MEP途径中DXR基因调控作用不明显。     

The effect of different maternal deprivation paradigms on the expression of hippocampal glucocorticoid receptors, calretinin and calbindin-D28k in male and female adolescent rats

Maternal deprivation (MD) is a well-established protocol used to investigate neurobiological changes that are associated with the etiology of and vulnerability to stress-related diseases in animal models. The resulting psychophysiological effects, the timing and duration of these adverse stimuli, and the method by which they exert their effects on the animals remain unclear. This study characterized differences in the hippocampal expression of glucocorticoid receptors (GRs) and the calcium-binding proteins calretinin (CALR) and calbindin-D28k (CALB) in male and female rats that underwent different MD paradigms during the stress hyporesponsive period (SHRP). Both GRs and the two calcium-binding proteins were much more abundant in females than in males. MD paradigms had a significant effect on CALR and CALB expression in both males and females but affected GR levels only in males. Additionally, expression of the two calcium-binding proteins in the hippocampus responded differently to MD-induced stress, especially in females. Taken together, these results indicate that females are able to modulate their response to stress better than males.