Multiplex PCR: use of heat-stable Thermus thermophilus RecA protein to minimize non-specific PCR products

In this paper we report that the inclusion of heat-resistant RecA protein from a thermophilic bacteria, Thermus thermophilus, and its cofactor (ATP) in PCR effectively eliminates non-specific PCR products. The effect of RecA protein, which catalyzes pairing between homologous DNA molecules with great fidelity in genetic recombination, is due to its promotion of precise priming in PCR (i.e. priming at sites where the primer sequence is completely complementary to that of the target sequence). In addition, the RecA protein substantially reduces the primer concentration required for PCR. These experimental results have led to the realization of multiplex PCR, which involves PCR for multiple sites in the same reaction mixture. We were able to successfully perform multiplex PCR with over a dozen reactions without affecting the amplification pattern of the PCR products

Induction of specific protein tyrosine phosphatase transcripts during differentiation of mouse embryonal carcinoma (F9) cells

AbstractWe have investigated the pattern of PTPase transcript expression during in vitro differentiation of mouse embryonal carcinoma (F9) cells. While the transcripts of most PTPases were unchanged or undetected during embryonal differentiation induced by retinoic acid, several PTPase transcripts exhibited distinct patterns of induction. Mutant cells defective in differentiation did not display the induction of some of these PTPase transcripts. Interestingly, three out of the four PTPase transcripts induced were the same PTPase transcripts induced during in vitro erythroid differentiation of mouse erythroleukemia (MEL) cells [(1982) Biochem. Biophys. Res. Commun. 107, 1104–1109]. The possible role played by specific PTPases in cell differentiation is discussed

The Incidence of Proximal Extension of Ulcerative Proctitis in Japan and Factors Related to Proximal Extension

The incidence of proximal extension in patients with ulcerative proctitis is reported to be 18%-46%, but recent data on the incidence in Japan is inadequate. The aim of this study was to investigate the incidence of proximal extension of ulcerative proctitis and factors associated with the extension in Japan. This is a retrospective observational study involving a cohort of 53 patients with an initial diagnosis of ulcerative proctitis. Following verification of the diagnoses, demographic and clinical data were compiled. The cumulative incidence of proximal extension was estimated as ‘person-years’ and cumulative probability was calculated by the Kaplan-Meyer method. Univariate and multivariate analyses were performed to identify association factors. During a mean follow-up of 6.8 years, proximal extension was observed in 14 patients (26.4%). The cumulative incidence of proximal extension was 4.22/100 person-years and the cumulative probability at 5 years was 20.1%, consistent with recent reports from Western countries and data obtained in Japan over 2 decades ago. Univariate analysis showed active smoking (P = 0.025) and corticosteroid therapy (P = 0.006) to be risk factors in proximal extension, however multivariate analysis revealed that corticosteroid therapy was the only significant factor (P = 0.005) separating patients with and without proximal extension. No patient underwent colectomy. The incidence of proximal extension in ulcerative proctitis in Japan is comparable to that in Western countries and has not changed significantly over the past two decades. Corticosteroid therapy was identified as the only significant factor in proximal extension

Amphotericin B assembles into seven-molecule ion channels: An NMR and molecular dynamics study

Amphotericin B, an antifungal drug with a long history of use, forms fungicidal ion-permeable channels across cell membranes. Using solid-state nuclear magnetic resonance spectroscopy and molecular dynamics simulations, we experimentally elucidated the three-dimensional structure of the molecular assemblies formed by this drug in membranes in the presence of the fungal sterol ergosterol. A stable assembly consisting of seven drug molecules was observed to form an ion conductive channel. The structure is somewhat similar to the upper half of the barrel-stave model proposed in the 1970s but substantially different in the number of molecules and in their arrangement. The present structure explains many previous findings, including structure-activity relationships of the drug, which will be useful for improving drug efficacy and reducing adverse effects

Genotyping of Mycoplasma pneumoniae strains isolated in Japan during 2019 and 2020: spread of p1 gene type 2c and 2j variant strains

We characterized 118 Mycoplasma pneumoniae strains isolated from three areas of Japan (Saitama, Kanagawa, and Osaka) during the period of 2019 and 2020. Genotyping of the p1 gene in these strains revealed that 29 of them were type 1 lineage (29/118, 24.6%), while 89 were type 2 lineage (89/118, 75.4%), thereby indicating that type 2 lineage was dominant in this period. The most prevalent variant of type 2 lineage was type 2c (57/89, 64%), while the second-most was type 2j, a novel variant identified in this study (30/89, 33.7%). Type 2j p1 is similar to type 2 g p1, but cannot be distinguished from reference type 2 (classical type 2) using the standard polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP) with HaeIII digestion. Thus, we used MboI digestion in the PCR-RFLP analysis and re-examined the data from previous genotyping studies as well. This revealed that most strains reported as classical type 2 after 2010 in our studies were actually type 2j. The revised genotyping data showed that the type 2c and 2j strains have been spreading in recent years and were the most prevalent variants in Japan during the time-period of 2019 and 2020. We also analyzed the macrolide-resistance (MR) mutations in the 118 strains. MR mutations in the 23S rRNA gene were detected in 29 of these strains (29/118, 24.6%). The MR rate of type 1 lineage (14/29, 48.3%) was still higher than that of type 2 lineage (15/89, 16.9%); however, the MR rate of type 1 lineage was lower than that found in previous reports published in the 2010s, while that of type 2 lineage strains was slightly higher. Thus, there is a need for continuous surveillance of the p1 genotype and MR rate of M. pneumoniae clinical strains, to better understand the epidemiology and variant evolution of this pathogen, although M. pneumoniae pneumonia cases have decreased significantly since the COVID-19 pandemic

チーター（Acinonyx jubatus）における半規管の配置と直交性について

The purpose of this study was to clarify the spatial orientation of the semicircular canals in the cheetah (Acinonyx jubatus) using computed tomography (CT). CT scan was performed on the skull of a cheetah. Scanning data were reconstructed into the cross-sectional images, and then the landmark coordinates were determined to define the planes of the semicircular canals and the cross-sections of the skull. In the cheetah, the lateral semicircular canal was parallel to the base of the skull. The angles between the anterior and posterior semicircular canals was lager than 90 degrees, and each canal showed the similar angle with the sagittal cross-section of the skull, although these planar directions were different. One limitation of this study is that here we provided only one specimen, and thus the present results need to be confirmed by examining a larger number of cases in future studies. However, the method outlined in this study provided quantitative descriptions of orientations and orthogonalities of the semicircular canals of the cheetah. This is potentially useful for indentifying the morphological features of the semicircular canals in felids

アメリカグマ（Ursus americanus），マレーグマ（Helarctos malayanus），ホッキョクグマ（Ursus maritimus）における手内筋の筋重量について

The hands of the American black bear (Ursus americanus), the sun bear (Helarctos malayanus), the polar bear (Ursus maritimus), and the lion (Panthera leo) were dissected and the mass of the intrinsic hand muscles were systematically recorded to explore possible interspecies variation. Muscle mass was divided by the third metacarpal bone size for normalization. The results indicated that the normalized muscle masses of the thenar muscles were larger in the three bears than the lion, and the abductor pollicis muscle was larger in the sun bear than other bears. For the abductor digiti minimi muscle, the normalized muscle mass was larger in the three bears than the lion, but smaller in the polar bear among three bears. One limitation of this study is that here we provided only one specimen for each species, and thus the present results need to be confirmed by examining a larger number of cases in future studies. However, these differences in the intrinsic hand muscles of the four species may reflect adaptation for their different habits

Daytime nap and nighttime breastfeeding are associated with toddlers\u27 nighttime sleep

The purpose of the present study is to examine the association between toddlers\u27 sleep arrangements and their nighttime sleep duration and other sleep variables. For this investigation, we performed a study in which child activity and sleep levels were recorded using actigraphy. The parents of 1.5-year-old toddlers (n = 106) were asked to attach an actigraphy unit to their child’s waist with an adjustable elastic belt and complete a sleep diary for 7 consecutive days. Questionnaires were used to assess the sleep arrangements of the toddlers. There was a significant negative correlation between nap duration and nighttime sleep duration, suggesting that longer nap sleep induces shorter nighttime sleep duration. Among the sleep arrangements, such as nighttime breastfeeding or co-sleeping, only nighttime breastfeeding predicted shorter nighttime sleep duration. Our findings indicate that shorter naps induce a longer nighttime sleep in 1.5-year-old toddlers while nighttime breastfeeding decreases their nighttime sleep duration

Sleep maturation influences cognitive development of preterm toddlers

Our recent study on full-term toddlers demonstrated that daytime nap properties affect the distribution ratio between nap and nighttime sleep duration in total sleep time but does not affect the overall total amount of daily sleep time. However, there is still no clear scientific consensus as to whether the ratio between naps and nighttime sleep or just daily total sleep duration itself is more important for healthy child development. In the current study, to gain an answer to this question, we examined the relationship between the sleep properties and the cognitive development of toddlers born prematurely using actigraphy and the Kyoto scale of psychological development (KSPD) test. 101 premature toddlers of approximately 1.5 years of age were recruited for the study. Actigraphy units were attached to their waist with an adjustable elastic belt for 7 consecutive days and a child sleep diary was completed by their parents. In the study, we found no significant correlation between either nap or nighttime sleep duration and cognitive development of the preterm toddlers. In contrast, we found that stable daily wake time was significantly associated with better cognitive development, suggesting that sleep regulation may contribute to the brain maturation of preterm toddlers