华北石质山地侧柏人工林C、N、P生态化学计量特征的季节变化

以北京九龙山自然保护区幼龄侧柏人工林为研究对象,对其不同生长季节叶、枝、根(0—10 cm、10—20 cm土层)的碳(C)、氮(N)、磷(P)含量及其生态化学计量学特征进行了分析,深入探讨了生长季节与器官以及两因素交互作用对以上特征的影响,研究有助于理解植物各性状之间的相互作用以及植物生长过程中资源的利用和分配状况。结果表明:1)不同器官间C含量为414.97—461.58 g/kg,枝最大,根(0—10 cm)最小;N含量为6.57—14.28 g/kg,叶最大,枝最小;P含量为0.39—1.28 g/kg,叶最大,根(10—20 cm)最小;C∶N为31.76—70.98,枝最大,叶最小;C∶P为369.93—1099.20,根(10—20 cm)最大,叶最小;N∶P为9.21—23.81,根(0—10 cm)最大,枝最小。整个生长季节中侧柏各器官C含量最稳定,变异系数均小于7%;P含量变异性最大,变异系数均超过15%,N含量变异性介于两者之间;各器官中C∶N和N∶P较C∶P更为稳定,C、N与P具有较好的耦合协同性,C∶P和N∶P的变化主要取决于P的变化。2)器官对C、N、P含量及其化学计量关系均存在显著影响,生长季节对N和P含量存在显著影响,两者交互作用只对P含量存在显著影响,器官对侧柏C、N、P含量及其化学计量变异的贡献大于生长季节。3)侧柏各器官间C、N、P含量及其化学计量比相关性多数未达到显著性水平,仅有叶与枝中的P及C∶P显著相关,说明侧柏器官分化过程中各器官对元素的吸收利用具有特异性。侧柏叶片N∶P14,说明生长季节里幼龄侧柏人工林更多受到N限制。     

Effects of stress and food deprivation on catfish, Heteropneustes fossilis (Bloch)

No significant changes in plasma cortisol and plasma osmolarity (the indicators of primary and secondary response respectively) were observed when the blood samples were obtained from unanaesthetized, anaesthetized and stressed catfish, H. fossilis. The results suggest that the catfish is fairly hardy and not easily susceptible to stress by routine laboratory handling. The sustained plasma glucose levels and decreased liver and muscle glycogen concentrations during cessation of feeding of the catfish suggest that during period of food deprivation, it draws its energy through glycogenolysis. Hence, in any study dealing with carbohydrate metabolism, the catfish needs to be fed during acclimation and experimental periods.     

The origin of interspersed repeats in the human genome

Over a third of the human genome consists of interspersed repetitive sequences which are primarily degenerate copies of transposable elements. In the past year, the identities of many of these transposable elements were revealed. The emerging concept is that only three mechanisms of amplification are responsible for the vast majority of interspersed repeats and that with each autonomous element a number of dependent non-autonomous sequences have co-amplified.     

Anomalous Cases of Conjugation and Spontaneous Autogamy in Stylonychia mytilus: A Note on the Asexuality of Early Conjugants

Four types of anomalous conjugation were documented in Stylonychia mytilus. Type I pairs were formed between mates of different sizes. These pairs exhibited an abnormal site of fusion in at least one of the mates, and the mates might face each other ventrally throughout conjugation instead of the normal side-by-side position. Type I pairs underwent sexual nuclear development and proceeded with the first cortical reorganization as in normal conjugants. Type II involved pairing at the anterior ends of mates with ventral surfaces facing the same direction. These pairs also underwent sexual nuclear development. Hence, aberrant orientation of the mates, and also ectopic sites of cytoplasmic fusion, if extensive, would permit sexual development. Type III pairs were united ventral-to-ventral with their anterior-left sides at the adoral zone of membranelles, and remained as such throughout conjugation. In these pairs, nuclear and cortical events were typical of the asexual development of physiological reorganization. In Type IV pairs, one mate of the pair possessed a fission furrow and developed two sets of ciliature typical of binary fission, while the other mate might undergo physiological reorganization or binary fission. Type III and Type IV pairs thus reveal the asexual state of early conjugants, which can pursue either one of the two modes of asexual cortical reorganization; these cases reinforce the notion of overlap of asexual and sexual cycles during conjugation of hypotrichs. Spontaneous autogamy was documented for the first time for this genus. The autogamonts proceeded with nuclear development and with the first cortical reorganization. Some probably underwent second and third reorganizations, as in conjugants, but accompanied by abnormalities, particularly in the stages beyond fertilization. Post-autogamous clones were nonviable except for one dubious case.     

犁头霉11α-羟基化制备16β-甲基-11α,17α,21-三羟基孕甾-1,4-二烯-3,20-二酮

选育到一株对16β-甲基,17α,21-二羟基孕甾-1,4-二烯-3,20-二酮(Ⅱa)11α-羟基化活性强的犁头霉A28菌株,并发现底物21-乙酰化(Ⅱb)可明显提高11α-羟基化的能力.在适宜的转化条件下,Ⅱb投料浓度0.5%,产物16β-甲基-11α,11α,21-三羟基孕甾-1,4-二烯-3,20-二酮(Ⅲ)收率为73%,结构经波谱分析确认.     

Multicellular compartmentation of catharanthus roseus alkaloid biosynthesis predicts intercellular translocation of a pathway intermediate

In situ RNA hybridization and immunocytochemistry were used to establish the cellular distribution of monoterpenoid indole alkaloid biosynthesis in Madagascar periwinkle (Catharanthus roseus). Tryptophan decarboxylase (TDC) and strictosidine synthase (STR1), which are involved in the biosynthesis of the central intermediate strictosidine, and desacetoxyvindoline 4-hydroxylase (D4H) and deacetylvindoline 4-O-acetyltransferase (DAT), which are involved in the terminal steps of vindoline biosynthesis, were localized. tdc and str1 mRNAs were present in the epidermis of stems, leaves, and flower buds, whereas they appeared in most protoderm and cortical cells around the apical meristem of root tips. In marked contrast, d4h and dat mRNAs were associated with the laticifer and idioblast cells of leaves, stems, and flower buds. Immunocytochemical localization for TDC, D4H, and DAT proteins confirmed the differential localization of early and late stages of vindoline biosynthesis. Therefore, we concluded that the elaboration of the major leaf alkaloids involves the participation of at least two cell types and requires the intercellular translocation of a pathway intermediate. A basipetal gradient of expression in maturing leaves also was shown for all four genes by in situ RNA hybridization studies and by complementary studies with dissected leaves, suggesting that expression of the vindoline pathway occurs transiently during early leaf development. These results partially explain why attempts to produce vindoline by cell culture technology have failed.     

SA-hIL2双功能融合蛋白的研制及其生物学鉴定

目的：制备链亲和素标记的人白细胞介素-2(SA-hIL2)融合蛋白,并研究其生物学功能。方法：构建SA-L-IL2-pET24重组表达质粒,在大肠杆菌中表达SA-hIL2融合蛋白,对表达的SA-hIL2融合蛋白采用镍金属螯合（Ni-NTA）层析柱进行纯化,透析复性。CCK-8法检测SA-hIL2融合蛋白对PHA刺激的人外周血淋巴细胞的增值活性,流式细胞仪分析SA-hIL2融合蛋白对生物素化的B16.F10肿瘤细胞表面锚定修饰效率。结果：SA-hIL2在大肠杆菌中实现了高效表达,约占菌体总蛋白的20％,制备的SA-hIL2融合蛋白纯度达到95％,并具有双重活性,即hIL-2促进PHA刺激的人外周血淋巴细胞的增值活性和SA介导的高效结合至已生物素化的B16.F10肿瘤细胞表面的功能（表面锚定修饰效率约95％）。结论：研制的SA-hIL2融合蛋白具有双重活性,可为研制表面修饰的新型肿瘤细胞疫苗提供基础。     

Visual stabilization of the eyes in primates

Observers moving through a texture three-dimensional world experience potentially confusing patterns of optic flow. Recent experiments on monkeys and humans have revealed the existence of rapid, yet cortically mediated, reflex eye movements that automatically single out images in the plane of fixation for stabilization and ignore images that are nearer or further.     

Wheat kernel dimensions: how do they contribute to kernel weight at an individual QTL level?

Kernel dimensions (KD) contribute greatly to thousand-kernel weight (TKW) in wheat. In the present study, quantitative trait loci (QTL) for TKW, kernel length (KL), kernel width (KW) and kernel diameter ratio (KDR) were detected by both conditional and unconditional QTL mapping methods. Two related F(8:9) recombinant inbred line (RIL) populations, comprising 485 and 229 lines, respectively, were used in this study, and the trait phenotypes were evaluated in four environments. Unconditional QTL mapping analysis detected 77 additive QTL for four traits in two populations. Of these, 24 QTL were verified in at least three trials, and five of them were major QTL, thus being of great value for marker assisted selection in breeding programmes. Conditional QTL mapping analysis, compared with unconditional QTL mapping analysis, resulted in reduction in the number of QTL for TKW due to the elimination of TKW variations caused by its conditional traits; based on which we first dissected genetic control system involved in the synthetic process between TKW and KD at an individual QTL level. Results indicated that, at the QTL level, KW had the strongest influence on TKW, followed by KL, and KDR had the lowest level contribution to TKW. In addition, the present study proved that it is not all-inclusive to determine genetic relationships of a pairwise QTL for two related/causal traits based on whether they were co-located. Thus, conditional QTL mapping method should be used to evaluate possible genetic relationships of two related/causal traits.     

Two new cytotypes reinforce that <Emphasis Type="Italic">Micronycteris hirsuta</Emphasis> Peters, 1869 does not represent a monotypic taxon

Background

The genus Micronycteris is a diverse group of phyllostomid bats currently comprising 11 species, with diploid number (2n) ranging from 26 to 40 chromosomes. The karyotypic relationships within Micronycteris and between Micronycteris and other phyllostomids remain poorly understood. The karyotype of Micronycteris hirsuta is of particular interest: three different diploid numbers were reported for this species in South and Central Americas with 2n?=?26, 28 and 30 chromosomes. Although current evidence suggests some geographic differentiation among populations of M. hirsuta based on chromosomal, morphological, and nuclear and mitochondrial DNA markers, the recognition of new species or subspecies has been avoided due to the need for additional data, mainly chromosomal data.

Results

We describe two new cytotypes for Micronycteris hirsuta (MHI) (2n?=?26 and 25, NF?=?32), whose differences in diploid number are interpreted as the products of Robertsonian rearrangements. C-banding revealed a small amount of constitutive heterochromatin at the centromere and the NOR was located in the interstitial portion of the short arm of a second pair, confirmed by FISH. Telomeric probes hybridized to the centromeric regions and weakly to telomeric regions of most chromosomes. The G-banding analysis and chromosome painting with whole chromosome probes from Carollia brevicauda (CBR) and Phyllostomus hastatus (PHA) enabled the establishment of genome-wide homologies between MHI, CBR and PHA.

Conclusions

The karyotypes of Brazilian specimens of Micronycteris hirsuta described here are new to Micronycteris and reinforce that M. hirsuta does not represent a monotypic taxon. Our results corroborate the hypothesis of karyotypic megaevolution within Micronycteris, and strong evidence for this is that the entire chromosome complement of M. hirsuta was shown to be derivative with respect to species compared in this study.