RECQL5基因的结构及其生物学功能的研究进展

RECQL5(Rec Q protein-like 5)是Rec Q DNA解旋酶家族的一个成员,同属于DEXH-box DNA/RNA解旋酶家族。Rec Q家族中的三成员(WRN、BLM、RECQL4)基因突变与人类一些遗传疾病相关,而RECQL5基因至今未发现与人类疾病相关。近年来研究发现,RECQL5对维持DNA的稳定以及在DNA的复制、修复、重组和转录等过程中发挥着非常重要的作用。该文主要对RECQL5基因的结构及其在DNA复制、修复和转录等方面的作用进行综述。     

Schlafen家族蛋白在肿瘤和病毒感染中的研究进展

Schlafen (SLFN)家族基因是在人类与小鼠中首先被发现的具有调控细胞生长及T细胞分化等诸多生物学功能的重要基因。该家族基因在小鼠、马和人等各个物种中广泛存在并具有较高的同源性。研究表明,SLFN蛋白在抑制细胞增殖、驱动减数分裂、调控造血细胞、下调血小板数量及调节免疫应答等方面均起到重要的作用,同时还可抑制HIV-1和流感等病毒复制。此外,SLFN蛋白还被发现与肿瘤的治疗密切相关,可以作为预测肿瘤发展进程和化疗敏感性的分子标记。本文介绍了SLFN家族蛋白的分类、结构和主要特征、定位与功能,重点综述了其在肿瘤和病毒感染等相关领域的研究进展,以期为SLFN蛋白新功能的探究提供新思路,对蛋白发挥作用的可能机制给予提示,并为各相关领域的研究提供参考。     

血管抑制素基因的克隆及表达

多年来,肿瘤的转移一直是肿瘤治疗的极大障碍,而血管抑制素(angiostatin)的发现很可能对肿瘤及其转移的治疗有重要意义。血管抑制素是从荷Luwis肿瘤小鼠血、尿中分离到的一种同源于纤维蛋白酶原内片段的多肽,在体外可抑制血管内皮细胞生长,在体内可显著抑制肿瘤组织转移及继发肿瘤的生长。故获得持续来源的血管抑制素对于肿瘤转移的治疗及     

罗仙子提取物对肝癌的体内外抑制作用研究

本文观察中药罗仙子提取物在离体细胞水平以及整体动物模型中对肝癌的治疗作用。在罗仙子提取物干预人肝癌SMMC-7721细胞24 h后,采用MTT法检测细胞活率;采用光学显微镜、荧光显微镜、透射电镜观察细胞形态学改变,流式细胞仪检测细胞凋亡率;以Heps肝癌小鼠模型观察罗仙子提取物体内对肿瘤生长的抑制作用。研究发现不同浓度罗仙子提取物可抑制SMMC-7721细胞增殖同时诱导典型的细胞凋亡形态学变化,与对照组相比细胞凋亡率显著升高,且具有浓度依赖性;不同浓度罗仙子提取物可显著抑制Heps肝癌小鼠体内肿瘤生长。实验证明罗仙子提取物可显著抑制Heps肝癌小鼠体内肿瘤生长,该作用可能与罗仙子提取物抑制肝癌细胞增殖、诱导细胞凋亡有关。     

Smad2条件基因剔除载体的构建及LoxP位点有效性鉴定

Smads家族是最新发现的TGF－β信号转导途径中一个重要的新基因家族,SMAD2属于受体激活的SMADs。Smad2在某些肿瘤中发生突变,是一种可能的肿瘤抑制基因。Smad2基因完全剔除小鼠在胚胎期E6．5天死亡,为了研究Smad2在成体各组织器官及肿瘤发生中的可能作用,构建了Smad2条件基因剔除载体,将LoxP置于Smad2基因组序列C末端功能域两侧,并在组成型表达Cre重组酶的大肠杆菌中检测了LoxP位点的功能,该载体的构建为进行Smad2组织特异性基因剔除研究了奠定了基础。     

蜈龙抗癌颗粒对小鼠移植性肿瘤的治疗实验

目的　观察新药“蜈龙抗癌颗粒”对四种小鼠移植性肿瘤的治疗效果 ,初步探讨该制剂对小鼠的毒副作用。方法　在小鼠急性毒性试验的基础上 ,选择三个剂量对小鼠移植性肿瘤Lewis肺癌、P388白血病、S1 80 肉瘤和H2 2 肝癌进行治疗实验 ,同时检查一批治疗Lewis肺癌实验小鼠的 15项血液学指标和脾脏、胸腺的相对重量。结果与结论　“蜈龙抗癌颗粒”在生药剂量为每日每公斤体重 10、2 5、4 0g(Lewis肺癌、P388白血病 )和每日每公斤体重 15、30、5 0g(S1 80 肉瘤和H2 2 肝癌 )时 ,对小鼠移植性肿瘤有肯定的治疗效果 ,并呈良好的量效关系 ,对小鼠Lewis肺癌的治疗效果最明显。该制剂大剂量时可能对小鼠的造血系统和免疫系统有明显影响。     

MOTS-c通过TLR4对肠源性脓毒症的作用及其机制

目的:脓毒症是机体对感染产生的全身性炎症反应综合征,由于具体机制尚不明确,临床治疗效果不佳,死亡率一直居高不下。本实验通过研究线粒体来源多肽MOTS-c通过影响Toll样受体4在肠源性脓毒症小鼠模型中的作用及其相关机制,寻找新的临床治疗靶标,为感染性疾病的研究开拓新的思路。方法:在盲肠结扎穿孔(CLP)所致肠源性脓毒症小鼠给予MOTS-c处理后检测小肠组织中检测炎症相关因子TNF-α,IL-6,IL-1β水平,检测TLR4表达水平,并且在野生型和TLR4过表达小鼠中构建CLP模型并给予MOTS-c处理,将其与对照组进行比较,以明确TLR4在MOTS-c对脓毒症影响中的作用。结果:在MOTS-c组CLP小鼠模型中,小鼠体内促炎因子TNF-α,IL-6,IL-1β水平与对照组相比显著降低(P0.05),此外,TLR4与对照组相比表达下降,进一步在TLR4过表达小鼠CLP模型中对小鼠给予MOTS-c处理发现,MOTS-c对小鼠CLP的抗炎作用被抑制,小鼠体内促炎性因子TNF-α,IL-6,IL-1β水平与野生型小鼠比较均显著上升,差异具有统计学意义,说明过表达TLR4逆转了MOTS-c的抗炎作用,提示MOTS-c可以在肠源性脓毒症中发挥抗炎作用,并且此过程可能依赖于TLR4。结论:MOTS-c可以在脓毒症中抑制小肠上皮细胞中TLR4过度激活,最终抑制炎症,因此可能对脓毒症有治疗效果,有望用于临床治疗。     

红色诺卡氏菌细胞壁骨架对小鼠肝癌细胞生长的抑制效果

目的:通过构建H22荷瘤小鼠模型,观察红色诺卡氏菌细胞壁骨架(Nocardia Rubra Cell Wall Skeleton,N-CWS)对H22荷瘤小鼠肝癌细胞生长的抑制效果。方法:复苏并培养H22细胞,将H22细胞以皮下方式接种到小鼠右侧腋部,建立H22荷瘤小鼠肝癌模型,随机分为对照组(生理盐水组)、低浓度N-CWS组(400μg/m L)与高浓度N-CWS组(800μg/m L),分别灌胃1次/d,共灌胃14 d,最长接种肿瘤15 d后处死小鼠,观察肝癌细胞的大小和重量。结果:治疗组小鼠肿瘤质量明显低于对照组(1.46±0.16)g,且高浓度组小鼠肿瘤质量(0.52±0.13)g明显低于低浓度组(0.79±0.13)g,组间对比差异有统计学意义(P0.05)。在治疗第3 d起直至结束,治疗组小鼠肿瘤体积均明显低于对照组,从第5 d起直至结束,高浓度组小鼠肿瘤体积明显低于低浓度组(P0.05)。第5 d起至结束,治疗组小鼠肿瘤体积增长的变化明显缓于对照组(P0.05)。高浓度组小鼠肿瘤体积的增长在第5 d后明显缓于低浓度组(P0.05)。对照组在第9 d时,增长变化最为显著,较第7 d增加约400 mm3。低浓度组变化较稳定。高浓度组肿瘤增长明显变缓,第7 d后最为明显,后逐渐趋于缓和。结论:N-CWS可以明显抑制肿瘤生长,且高浓度N-CWS抑制肿瘤生长效果更佳。     

MicroRNA与肿瘤相关的信号转导通路

信号转导通路在细胞代谢、生长、增殖、应激、发育和凋亡等生命活动中具有极为重要的作用。干扰这些通路将可能影响细胞的正常发育, 甚至导致肿瘤。MicroRNA(miRNA)是近年来在真核生物中发现的、在转录后水平负调节基因表达的一类长度约22个核苷酸的非编码小RNA, 其靶基因数目众多, 生物学功能广泛。在多种肿瘤中发现了miRNA的异常表达, 提示后者与肿瘤发生有关, 可能机制为调控癌基因或肿瘤抑制基因的表达。此外亦发现miRNA的靶基因有许多作用于肿瘤相关的信号转导通路。miRNA在肿瘤发生过程中的重要调控功能预示其将成为人类癌症诊断和治疗方面的新星。     

抗CD90单克隆抗体在治疗黑色素细胞瘤中的基础研究

目的:探讨应用抗CD90单克隆抗体治疗黑色素细胞瘤的可行性及相关机制。方法:首先通过流式细胞检测技术,探究抗CD90单克隆抗体是否能在体外诱导B16细胞凋亡。之后,通过向C57BL/6J小鼠皮下注射B16细胞建立小鼠黑色素瘤模型,并给予抗CD90单克隆抗体治疗,评价其抗肿瘤的治疗效果。同时,应用免疫组织化学的方法观察小鼠成瘤组织中新生血管的形成和分布情况,统计肿瘤中微血管密度进行比较。结果:抗CD90单克隆抗体在体外不能直接诱导B16细胞凋亡,但抗CD90单克隆抗体能够抑制小鼠黑色素瘤的原位生长(p=0.049);使用免疫组织化学染色法对肿瘤组织切片进行染色,发现经过抗体治疗的小鼠成瘤组织中的新生血管明显减少,治疗组和对照组肿瘤组织的微血管密度存在显著性差异(p=0.011)。结论:抗CD90单克隆抗体能够通过抑制肿瘤组织中新生血管的形成影响黑色素瘤的发生发展,从而达到治疗黑色素瘤的效果。     

Ectogenesis and the case against the right to the death of the foetus

Ectogenesis, or the use of an artificial womb to allow a foetus to develop, will likely become a reality within a few decades, and could significantly affect the abortion debate. We first examine the implications for Judith Jarvis Thomson’s violinist analogy, which argues for a woman’s right to withdraw life support from the foetus and so terminate her pregnancy, even if the foetus is granted full moral status. We show that on Thomson’s reasoning, there is no right to the death of the foetus, and abortion is not permissible if ectogenesis is available, provided it is safe and inexpensive. This raises the question of whether there are persuasive reasons for the right to the death of the foetus that could be exercised in the context of ectogenesis. Eric Mathison and Jeremy Davis have examined several arguments for this right, doubting that it exists, while Joona Räsänen has recently criticized their reasoning. We respond to Räsänen’s analysis, concluding that his arguments are unsuccessful, and that there is no right to the death of the foetus in these circumstances.     

On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

---

Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Arranging the elements of the potassium channel: the T1 domain occludes the cytoplasmic face of the channel

The voltage-gated potassium channel is currently one of the few membrane proteins where functional roles have been mapped onto specific segments of sequence. Although high-resolution structures of the transmembrane portions of three bacterial potassium channels, the tetramerization domain and the cytoplasmic ball are available, their relative spatial arrangement in mammalian channels remains a matter of ongoing debate. Cryo-electron microscopic images of the six transmembrane voltage-gated Kv channel have been reconstructed at up to 18 Å resolution, revealing that the T1 domain tetramerizes and is suspended below the transmembrane segments. However, the resolution of these images is insufficient to reveal the location of the third piece of the puzzle, the inactivating ball domain. We have used the aberrant interactions observed in a series of chimæric channels to establish that an assembled T1 domain restricts access to the cytoplasmic face of the channel, suggesting that the N-terminal ball and chain may be confined in the space between the T1 domain and the transmembrane portion of the channel.     

Feeding the vertebrate retina from the Cambrian to the Tertiary

The retina of the vertebrate eye is metabolically active and requires nutritive support. During the last 540 million years it has evolved into forms as complicated and nutritionally demanding as those found in avian or primate eyes. Diffusion from the choroid is generally able to supply the metabolic needs of thin retinae. However, when the thickness exceeds the limits of diffusion, structures are needed to supplement the vascular supply from the choroid. These supplemental nutritive devices include the choroidal gland, the falciform process and preretinal vascular plexus of fish, the conus papillaris of lizards, the pecten oculi of birds, the intraretinal vessels of mammals and a few novel systems that remain difficult to classify. These vascular systems are among the most variable features of the vertebrate eye. Here, we review classical and recent findings regarding such retinal nutrition systems, propose a three category classification for them based on histologic origins and speculate on the evolutionary forces which drove their development.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418