Effects of the IQ1 motif of Drosophila myosin-5 on the calcium interaction of calmodulin.

In Drosophila compound eyes, myosin-5 (DmMyo5) plays a key role in organelle transportation, including transporting pigment granules from the distal end to the proximal end of the photoreceptor cells to regulate the amount of light reaching the photosensitive membrane organelle rhabdomere. It is generally accepted that, upon exposure to light, the dark-adapted compound eyes produce a rapid rise of free Ca2+ concentration, which in turn activates DmMyo5 to transport pigment granules. Considering the dynamic and compartmentation of Ca2+ signaling in photoreceptor cells during light exposure, it is necessary to understand the kinetics of Ca2+ interaction with DmMyo5. Here, we investigated the interaction of Ca2+ with Drosophila calmodulin (CaM) in complex with the IQ1 of DmMyo5 using steady-state and kinetic approaches. Our results show that IQ1 binding substantially increases the Ca2+ affinity of CaM and decreases the dissociation rate of Ca2+ from CaM. In addition, we found that Mlc-C, the light chain associated with the IQ2 of DmMyo5, has little effect on the Ca2+ kinetics of CaM in IQ1. We propose that, by decreasing the Ca2+ dissociation rate from CaM, IQ1 delays the deactivation of DmMyo5 after Ca2+ transition, thereby prolonging the DmMyo5-driven transportation of pigment granules.

An Integrated Analysis of Risk Factors of Cognitive Impairment in Patients with Severe Carotid Artery Stenosis.

OBJECTIVE: To investigate cognitive dysfunction in patients with carotid artery stenosis (CAS) and potential risk factors related to cognitive-especially memory-dysfunction. METHODS: Forty-seven patients with carotid artery stenosis were recruited into our study cohort. The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) were adopted to assess cognitive function, the Wechsler Memory Scale (WMS) to assess memory function, high-resolution MRI and enhanced ultrasound to evaluate carotid plaques, and computed tomography perfusion (CTP) imaging to evaluate intracranial blood perfusion. Single-factor analysis and multiple-factor regression analysis were used to analyze potential risk factors of cognitive impairment. RESULTS: Mini-Mental State Examination test results showed that 22 patients had cognitive impairment, and MoCA test results showed that 10 patients had cognitive impairment. Analysis of various risk factors indicated that the average memory quotient of female patients was higher than that of males (P = 0.024). The cognitive and memory performance of those with an educational background above high school were significantly better than those of participants with high school or lower (P = 0.045). Patients with abnormal intracranial perfusion performed worse on the MMSE test (P = 0.024), and their WMS scores were significantly lower (P = 0.007). The MMSE scores and the memory quotients were significantly lower in patients with a history of cerebral infarction (MMSE, P = 0.047, memory quotient score, P = 0.018). CONCLUSION: A history of cerebral infarction and abnormal cerebral perfusion are associated with decline in overall cognitive function and memory in patients with carotid stenosis. Being female and having an educational background above high school may be protective factors in the development of cognitive dysfunction.

Novel APP K724M mutation causes Chinese early-onset familial Alzheimer's disease and increases amyloid-ß42 to amyloid-ß40 ratio.

Alzheimer's disease (AD) is the most common neurodegenerative disorder among the elderly individuals. Although there are several million cases of AD estimated in China with the most population in the world, no Chinese early-onset familial AD caused by new APP gene mutation has ever been reported. Here, we first described a Chinese family with early-onset AD that was inherited in autosomal dominant manner, and the age of onset was 46.6 ± 7.7 years (n = 5; range, 40-58 years). By using genetic analysis of 3 collected patients' DNA samples, we identified a heterozygous APP gene mutation (g.275363A>T, K724M according to APP770). Finally, when APP695 with K724M mutation was ectopically expressed in HEK293 cell, the ratio of amyloid-ß42 to amyloid-ß40 was 2.23-fold higher than that of wild-type control. Together, our data suggest that APP K724M gene mutation may contribute to the cause of this Chinese early-onset familial AD.

[Genetic characterization of Chinese rubella virus isolates from 2003 to 2007].

57 rubella virus strains were isolated using Vero cell line or Vero/SLAM cell line from patients' throat swabs during rubella outbreaks and sporadics in 10 provinces of China from 2003 to 2007. Fragments of 1107 nucleotides of E1 genes of the isolates were amplified by RT-PCR, the PCR products were directly sequenced and analyzed. The phylogenetic analysis based on 739 nucleotides showed that out of 57 Chinese rubella virus strains, 55 belong to a distinguish branch of 1E genotype when comparing with 1E genotype rubella strains from other countries, and the other 2 Chinese rubella virus strains belong to 2B genotype. Most of the nucleotide mutations of 57 rubella viruses were silent mutations, and the amino acid sequences were highly conserved. Except one amino acid change (Thr212 --> Ser212) in two rubella viruses at the hemagglutination inhibition and neutralization epitopes, there had no change found at the important antigenic epitope sites of the other rubella viruses. 1E genotype rubella viruses isolated from 10 provinces of China from 2003 to 2007, and two imported 2B genotype rubella viruses from Vietnam suggested that 1E genotype was the predominant genotype in this period of time. The rubella virus genotypes circulated during 2003 to 2007 were different from that circulating during 1979 to 1984 and 1999 to 2002, the rubella prevailed in recent years was mainly caused by 1E genotype rubella viruses with multi-transmission routes.