Nanometer-Resolution Long-term Tracking of Single Cargos Reveals Dynein Motor Mechanisms

Cytoplasmic dynein is essential for intracellular transport, but because of its complexity, we still do not fully understand how this 1.5 megadalton protein works. Here, we used novel optical probes that enable single-particle tracking (SPT) of individual cargos transported by dynein motors in live neurons over 900 μm. Analyses using the Fluctuation Theorem (FT) showed that the number of dynein molecules switches between 1-5 motors during the transport. Clearly resolved single-molecular steps revealed that the dwell times between individual steps were accurately described by an enzymatic cycle dominated by two equal and thermally-activated rate constants. Based on these data, we propose a new molecular model whereby each step requires the hydrolysis of 2 ATPs. The model is consistent with extensive structural, single-molecule and biochemical measurements.

Allosteric stabilization of calcium and lipid binding engages three synaptotagmins in fast exocytosis

The release of neurotransmitters from presynaptic terminals is a strongly Ca2+-dependent process controlled by synaptotagmins, especially by their C2B domains. Biochemical measurements have reported Ca2+ affinities of synaptotagmin too low to account for synaptic function. However, binding of the C2B domain to the membrane phospholipid PI(4,5)P2 increases the Ca2+ affinity and vice versa, indicating a positive allosteric stabilization of simultaneous binding. Here, we construct a mathematical model of the release-triggering mechanism of synaptotagmin based on measured Ca2+/PI(4,5)P2 affinities and reported protein copy numbers. The model reproduced the kinetics of synaptic transmission observed at the calyx of Held over the full range of Ca2+ stimuli, with each C2B domain crosslinking Ca2+ and PI(4,5)P2 lowering the energy barrier for fusion by 4.85 kBT. The allosteric stabilization of simultaneous Ca2+ and PI(4,5)P2 binding was crucial to form multiple crosslinks which enabled fast fusion rates. Only three crosslinking C2B domains were needed to reproduce physiological responses, but high copy numbers per vesicle sped up the collision-limited formation of crosslinks. In silico evaluation of theoretical mutants revealed that affection of the allosteric properties might be a determinant of the severity of synaptotagmin mutations and may underlie dominant-negative, disease-causing effects. We conclude that allostericity is a crucial feature of synaptotagmin action.

The role of kisspeptin and MKRN3 in the diagnosis of central precocious puberty in girls

Objective: To evaluate the characteristics and significance of serum kisspeptin and MKRN3 levels for the diagnostic of central precocious puberty (CPP) in girls. Method: 34 individuals with CPP, 17 individuals with premature thelarche (PT) and 28 age-matched prepubertal girls as normal control (NC) were recruited in this case-control study. Physical measurements included of body mass index and tests for breast, bone and sexual characteristics were carried out. Biochemical measurements included serum LH, FSH, estradiol, insulin-like growth factor-1, MKRN3 and kisspeptin. Blood samples were taken from individuals with CPP and PT before the gonadotrophin-releasing hormone stimulation test and at 30, 60, 90 and 120min after injection with triptorelin. Results: Serum kisspeptin levels were higher in the CPP group when compared to the NC group (P=0.020), while serum MKRN3 levels lower in the two groups (P=0.028). There were no significant differences between the CPP and PT groups as well as the PT and NC groups (all, P<0.05). The cut-off value of serum kisspeptin differentiating patients with CPP from those without CPP was 0.40nmol/L, with 82.4% sensitivity and 57.1% specificity; while the cut-off value of serum MKRN3 was 0.33pmol/L, with 79.4% sensitivity and 53.6% specificity. The area under the curves (AUCs) of both kisspeptin and MKRN3 for differentiating those girls with CPP from PT were less than 0.5. Conclusions: Serum levels of kisspeptin and MKRN3 may play an auxiliary role in predicting CPP. However, the two measurements were not able to differentiate girls with CPP from PT and prepubertal control. This study emphasizes the need to search for markers to simplify the accurate diagnosis of CPP in girls.

The association between subclinical hypothyroidism and TPOAb positivity with infertility in a population-based study: Tehran thyroid study (TTS)

Background Thyroid autoimmunity(TAI) is the most prevalent autoimmune condition in women of fertile age. There are increasing data regarding the association of thyroid dysfunction and thyroid autoimmunity with adverse pregnancy outcomes but there is no consensus regarding infertility and TPOAb positivity; thus we aimed to evaluate the association between thyroid TPOAb positivity and infertility in females and males in a population-based study (TTS). Methods Cross-sectional study of 3197 female and male participants in Tehran Thyroid Study (TTS) at the framework of the Tehran Lipid and Glucose Study (TLGS). Data included biochemical measurements and a self-administered questionnaire. Results A total of 12,823 cases in phase 4, 3719 cases (2108 female and 1611 male) were analyzed. The mean TSH of the infertile female and male was 2.52 ± 2.68 μIU/ml and 3.24 ± 10.26 μIU/ml respectively. The TPO median(IQR) of women with and without a history of infertility were 6.05 (3.30–13.96)and 6.04 (3.17–11.15);(P = 0.613), they were 5.08 (3.20–125.68) and 5.31 (3.93–125.68);(P = 0.490) in male participants, respectively. Results of crude and adjusted logistic regression analysis of the development of infertility by thyroid function and TPOAb, except for fT4 in male subjects, depicted no association between infertility and other variables in both crude and adjusted models. Conclusion Based on the result, thyroid autoimmunity was not associated with infertility in both females and males.

Circulating Prokineticin 2 Levels Are Increased in Children with Obesity and Correlated with Insulin Resistance

Objective. Prokineticin 2 (PK2) has been shown to regulate food intake, fat production, and the inflammation process, which play vital roles in the pathogenesis of obesity. The first aim of this study was to investigate serum PK2 levels in children with obesity and normal-weight children. The second aim was to compare the levels of PK2 between children with obesity, with and without nonalcoholic fatty liver disease (NAFLD). Methods. Seventy normal-weight children and 91 children with obesity (22 with NAFLD) were recruited. Circulating PK2, IL-6, and TNF-α were measured by enzyme-linked immunosorbent assays. Anthropometric and biochemical measurements related to adiposity, lipid profile, and insulin resistance were examined for all participants. Results. Serum PK2 was significantly higher in children with obesity than in the normal-weight controls. Circulating PK2 levels were not different between the patients with and without NAFLD. Circulating PK2 was positively correlated with BMI, BMI z-score, insulin, glucose, HOMA-IR, total cholesterol, low-density lipoprotein cholesterol, alanine aminotransferase, and gamma-glutamyl transpeptidase. Binary logistic regression revealed that the odds ratios for obesity were significantly elevated with increasing PK2. Conclusions. PK2 was strongly associated with obesity, and it may also be related to metabolic disorders and insulin resistance. This trial is registered with ChiCTR2000038838.

Effects of Different Packaging Materials on Storage Quality of Crisp Plum

This experiment uses “Bashan crisp plum” as the material, uses nano-bags and spontaneous modified atmosphere preservation bags for packaging, combined with 1-MCP fumigation treatment, and stores in a cold storage at 1±1.5℃. The physiological and biochemical measurements are measured every 15 days Indicators to discuss the low-temperature storage effects of different packaging materials. The results showed that the use of nano-bags and air-permeability of 3000mL/bag/24h modified atmosphere packaging can reduce fruit rot, delay the yellowing of the peel, better maintain the fruit texture and organic acid content, and better maintain the original fruit.

Metabolic syndrome amongst adults in Jordan: prevalence, trend, and its association with socio-demographic characteristics

Background Multiple epidemiological studies were conducted amongst a variety of ethnic groups and showed discrepancies in the prevalence of metabolic syndrome (MeS) and its individual components. This study aimed to determine the prevalence of MeS in Jordan using both the Adult Treatment Panel Guidelines (ATP III) and the International Diabetes Federation (IDF) criteria. The study also aimed to assess the changes in the prevalence of MeS over time and determine its association with sociodemographic variables. Methods Data from the 2017 Cardiovascular Disease Risk Factors Survey were used for this study. Socio-demographic and clinical data were collected using a structured questionnaire. Blood samples were taken for biochemical measurements. Furthermore, anthropometric characteristics were measured by the same team of trained field researchers. A sample of 4,056 individuals aged between 18 and 90 years was included in this study. The findings from the 2017 survey were compared with the findings of a 2009 survey that adopted the same methods and procedures. Results According to the IDF criteria, the crude prevalence of Metabolic syndrome was 48.2% (52.9% among men and 46.2% among women; p < 0.001). Using the ATP III criteria, the prevalence was 44.1% (51.4% among men and 41% among women, p < 0.001). The age-standardized prevalence rate of metabolic syndrome was 44% (95% CI 42.7, 45.4) and 39.9% (95% CI 39.6, 41.2), according to both the IDF definition and ATP III criteria, respectively. The Kappa measure of agreement showed excellent agreement between the two definitions (k = 81.9%, p < 0.001). Of all participants, 41.7% met both the IDF and ATP III diagnostic criteria, 6.6% met the IDF criteria only, and 2.5% met the ATP III criteria only. The age-standardized prevalence rate of metabolic syndrome was significantly higher in 2017 (45.7% in men and 44.5% in women) than that in 2009 survey (34.6% in men and 39.8% in women). Gender, age, occupation, region, and marital status were significantly associated with metabolic syndrome. Conclusions The prevalence of metabolic syndrome in Jordan is considerably high and it is increasing. Healthy lifestyle programs encouraging appropriate dietary habits and physical activity are strongly recommended in Jordan.