Human CCT4 and CCT5 Chaperonin Subunits Expressed in Escherichia coli Form Biologically Active Homo-oligomers

Chaperonins are a family of chaperones that encapsulate their substrates and assist their folding in an ATP-dependent manner. The ubiquitous eukaryotic chaperonin, TCP-1 ring complex (TRiC), is a hetero-oligomeric complex composed of two rings, each formed from eight different CCT (chaperonin containing TCP-1) subunits. Each CCT subunit may have distinct substrate recognition and ATP hydrolysis properties. We have expressed each human CCT subunit individually in Escherichia coli to investigate whether they form chaperonin-like double ring complexes. CCT4 and CCT5, but not the other six CCT subunits, formed high molecular weight complexes within the E. coli cells that sedimented about 20S in sucrose gradients. When CCT4 and CCT5 were purified, they were both organized as two back-to-back rings of eight subunits each, as seen by negative stain and cryo-electron microscopy. This morphology is consistent with that of the hetero-oligomeric double-ring TRiC purified from bovine testes and HeLa cells. Both CCT4 and CCT5 homo-oligomers hydrolyzed ATP at a rate similar to human TRiC and were active as assayed by luciferase refolding and human γD-crystallin aggregation suppression and refolding. Thus, both CCT4 and CCT5 homo-oligomers have the property of forming 8-fold double rings absent the other subunits, and these complexes carry out chaperonin reactions without other partner subunits.     

ECHOLOCATION IN DOLPHINS WITH A DOLPHIN-BAT COMPARISON

ABSTRACT

Dolphins possess a highly sophisticated auditory system and a keen capability for echolocation. Signals are emitted in the form of high intensity, short duration, broadband exponentially decaying pulses. The frequency spectra of echolocation signals used by many dolphins are dependent on the output intensity of the signals and not on any fine tuning by the animals. When the output intensity is low, the center frequency of the click tends to be low. As the output intensity increases, the center frequency also tends to increase. The pulses propagate from the dolphin's melon in a relatively narrow beam, and echoes are received via the lower jaw, with a slightly wider beam. Echo- locating dolphins can detect targets at ranges of approximately 100 plus meters, depending on the size of the targets. Target discrimination experiments have shown that dolphins can discriminate the shape, size, material composition and internal structure of targets from the echoes. The broadband short duration properties of the signal allow the echoes to have high temporal resolution, so that within the structure of the echoes a considerable amount of information on the properties of the target can be conveyed. A brief comparison between the bat and dolphin sonar system will also be made. Bats typically emit much longer signals and a wider variety of different types of signals than dolphins. Signals used by some bats are suited to detecting Doppler shift, whereas the dolphin signal is designed to be tolerant of Doppler effects.     

Chitin Coated Cellulose as an Adsorbent of lysozyme like Enzymes Preparation and Properties

As a new adsorbent of lysozyme-like enzymes, chitin coated (CC-)cellulose was prepared. CC-cellulose was stable and had good flow properties for use in column chromatography. Affinity chromatography with CC-cellulose showed that 3~5 mg of lysozyme/ml resin was adsorbed specifically and desorbed quantitatively under mild conditions. The utilities of the method of affinity chromatography with CC-cellulose are discussed.     

慢性阻塞性肺病患者急性加重期外周血IL-8、TNF-alpha及IGF-I表达变化 的意义

目的：研究慢性阻塞性肺病（COPD）患者急性加重期外周血白细胞介素-8（IL-8）、肿瘤坏死因子-a（TNF-a）及胰岛素样生长 因子-I（IGF-I）表达变化的临床意义。方法：选取2013 年12 月-2014 年12月我院收治的COPD 急性加重患者100 例为观察组, 选取同期健康体检者100 例为对照组,检测观察组患者治疗前、治疗稳定后及对照组外周血IL-8、TNF-alpha及IGF-I水平。结果：观 察组患者治疗前外周血IL-8、TNF-alpha及IGF-I水平显著高于治疗稳定后,差异有统计学意义（P＜ 0.05）;观察组患者治疗稳定后外 周血IL-8、TNF-alpha及IGF-I水平显著高于对照组,差异有统计学意义（P＜0.05）。结论：COPD 急性加重期外周血IL-8、TNF-琢及 IGF-I水平显著增高,治疗稳定后其水平显著降低,IL-8、TNF-alpha及IGF-I水平对COPD 的诊断和治疗具有重要意义。