How 5000 independent rowers coordinate their strokes in order to row into the sunlight: Phototaxis in the multicellular green alga Volvox

Ueki N, Matsunaga S, Inouye I, Hallmann A. How 5000 independent rowers coordinate their strokes in order to row into the sunlight: Phototaxis in the multicellular green alga Volvox. BMC Biology. 2010;8(1): 103.ABSTRACT: BACKGROUND: The evolution of multicellular motile organisms from unicellular ancestors required the utilization of previously evolved tactic behavior in a multicellular context. Volvocine green algae are uniquely suited for studying tactic responses during the transition to multicellularity because they range in complexity from unicellular to multicellular genera. Phototactic responses are essential for these flagellates because they need to orientate themselves to receive sufficient light for photosynthesis, but how does a multicellular organism accomplish phototaxis without any known direct communication among cells? Several aspects of the photoresponse have previously been analyzed in volvocine algae, particularly in the unicellular alga Chlamydomonas. RESULTS: In this study, the phototactic behavior in the spheroidal, multicellular volvocine green alga Volvox rousseletii (Volvocales, Chlorophyta) was analyzed. In response to light stimuli, not only did the flagella waveform and beat frequency change, but the effective stroke was reversed. Moreover, there was a photoresponse gradient from the anterior to the posterior pole of the spheroid, and only cells of the anterior hemisphere showed an effective response. The latter caused a reverse of the fluid flow that was confined to the anterior hemisphere. The responsiveness to light is consistent with an anterior-to-posterior size gradient of eyespots. At the posterior pole, the eyespots are tiny or absent, making the corresponding cells appear to be blind. Pulsed light stimulation of an immobilized spheroid was used to simulate the light fluctuation experienced by a rotating spheroid during phototaxis. The results demonstrated that in free-swimming spheroids, only those cells of the anterior hemisphere that face toward the light source reverse the beating direction in the presence of illumination; this behavior results in phototactic turning. Moreover, positive phototaxis is facilitated by gravitational forces. Under our conditions, V. rousseletii spheroids showed no negative phototaxis. CONCLUSIONS: On the basis of our results, we developed a mechanistic model that predicts the phototactic behavior in V. rousseletii. The model involves photoresponses, periodically changing light conditions, morphological polarity, rotation of the spheroid, two modes of flagellar beating, and the impact of gravity. Our results also indicate how recently evolved multicellular organisms adapted the phototactic capabilities of their unicellular ancestors to multicellular life

IDE Gene Polymorphism Influences on BPSD in Mild Dementia of Alzheimer's Type

Insulin degrading enzyme (IDE) degrades amyloid β (Aβ), which may inhibit the accumulation of Aβ in a brain affected with dementia of Alzheimer's type (DAT). A decrease in the activity of IDE results in changes in glucose utilization in the brain, which could affect the cognitive and psychiatric symptoms of DAT. We investigated a possible association of IDE gene polymorphism and the behavioral and psychological symptoms of dementia (BPSD) in mild DAT. The genotyping for IDE and apolipoprotein E (ApoE) was determined in 207 patients with mild DAT and 215 controls. The occurrence of BPSD was demonstrated using the Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD). IDE gene polymorphism is unlikely to play a substantial role in conferring susceptibility to DAT, but it may be involved in the development of affective disturbance through the course of mild DAT, regardless of the presence of an ApoE ε4 allele. The present data could be the result of a small sample size. Further investigations using larger samples are thus required to clarify the correlation between IDE gene polymorphism, susceptibility to DAT, and emergence of BPSD

Identification of the agg1 mutation responsible for negative phototaxis in a “wild-type” strain of Chlamydomonas reinhardtii

AbstractThe unicellular green alga Chlamydomonas reinhardtii is a model organism for various studies in biology. CC-124 is a laboratory strain widely used as a wild type. However, this strain is known to carry agg1 mutation, which causes cells to swim away from the light source (negative phototaxis), in contrast to the cells of other wild-type strains, which swim toward the light source (positive phototaxis). Here we identified the causative gene of agg1 (AGG1) using AFLP-based gene mapping and whole genome next-generation sequencing. This gene encodes a 36-kDa protein containing a Fibronectin type III domain and a CHORD-Sgt1 (CS) domain. The gene product is localized to the cell body and not to flagella or basal body

Control of pre-replicative complex during the division cycle in Chlamydomonas reinhardtii

DNA replication is fundamental to all living organisms. In yeast and animals, it is triggered by an assembly of pre-replicative complex including ORC, CDC6 and MCMs. Cyclin Dependent Kinase (CDK) regulates both assembly and firing of the pre-replicative complex. We tested temperature-sensitive mutants blocking Chlamydomonas DNA replication. The mutants were partially or completely defective in DNA replication and did not produce mitotic spindles. After a long G1, wild type Chlamydomonas cells enter a division phase when it undergoes multiple rapid synchronous divisions (‘multiple fission’). Using tagged transgenic strains, we found that MCM4 and MCM6 were localized to the nucleus throughout the entire multiple fission division cycle, except for transient cytoplasmic localization during each mitosis. Chlamydomonas CDC6 was transiently localized in nucleus in early division cycles. CDC6 protein levels were very low, probably due to proteasomal degradation. CDC6 levels were severely reduced by inactivation of CDKA1 (CDK1 ortholog) but not the plant-specific CDKB1. Proteasome inhibition did not detectably increase CDC6 levels in the cdka1 mutant, suggesting that CDKA1 might upregulate CDC6 at the transcriptional level. All of the DNA replication proteins tested were essentially undetectable until late G1. They accumulated specifically during multiple fission and then were degraded as cells completed their terminal divisions. We speculate that loading of origins with the MCM helicase may not occur until the end of the long G1, unlike in the budding yeast system. We also developed a simple assay for salt-resistant chromatin binding of MCM4, and found that tight MCM4 loading was dependent on ORC1, CDC6 and MCM6, but not on RNR1 or CDKB1. These results provide a microbial framework for approaching replication control in the plant kingdom

Clinical Study IDE Gene Polymorphism Influences on BPSD in Mild Dementia of Alzheimer's Type

Insulin degrading enzyme (IDE) degrades amyloid β (Aβ), which may inhibit the accumulation of Aβ in a brain affected with dementia of Alzheimer's type (DAT). A decrease in the activity of IDE results in changes in glucose utilization in the brain, which could affect the cognitive and psychiatric symptoms of DAT. We investigated a possible association of IDE gene polymorphism and the behavioral and psychological symptoms of dementia (BPSD) in mild DAT. The genotyping for IDE and apolipoprotein E (ApoE) was determined in 207 patients with mild DAT and 215 controls. The occurrence of BPSD was demonstrated using the Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD). IDE gene polymorphism is unlikely to play a substantial role in conferring susceptibility to DAT, but it may be involved in the development of affective disturbance through the course of mild DAT, regardless of the presence of an ApoE ε4 allele. The present data could be the result of a small sample size. Further investigations using larger samples are thus required to clarify the correlation between IDE gene polymorphism, susceptibility to DAT, and emergence of BPSD

Morphology, taxonomy and mating‑type loci in natural populations of Volvox carteri in Taiwan

Background: Volvox carteri f. nagariensis is a model taxon that has been studied extensively at the cellular and molecular level. The most distinctive morphological attribute of V. carteri f. nagariensis within V. carteri is the production of sexual male spheroids with only a 1:1 ratio of somatic cells to sperm packets or androgonidia (sperm packet initials). However, the morphology of male spheroids of V. carteri f. nagariensis has been examined only in Japanese strains. In addition, V. carteri f. nagariensis has heterothallic sexuality; male and female sexes are determined by the sex-determining chromosomal region or mating-type locus composed of a \u3e 1 Mbp linear chromosome. Fifteen sexspecific genes and many sex-based divergent shared genes (gametologs) are present within this region. Thus far, such genes have not been identified in natural populations of this species. Results: During a recent fieldwork in Taiwan, we encountered natural populations of V. carteri that had not previously been recorded from Taiwan. In total, 33 strains of this species were established from water samples collected in Northern Taiwan. Based on sequences of the internal transcribed spacer 2 region of nuclear ribosomal DNA and the presence of asexual spheroids with up to 16 gonidia, the species was clearly identified as V. carteri f. nagariensis. However, the sexual male spheroids of the Taiwanese strains generally exhibited a 1:1 to \u3e 50:1 ratio of somatic cells to androgonidia. We also investigated the presence or absence of several sex-specific genes and the sex-based divergent genes MAT3m, MAT3f and LEU1Sm. We did not identify recombination or deletion of such genes between the male and female mating-type locus haplotypes in 32 of the 33 strains. In one putative female strain, the female-specific gene HMG1f was not amplified by genomic polymerase chain reaction. When sexually induced, apparently normal female sexual spheroids developed in this strain. Conclusions: Male spheroids are actually variable within V. carteri f. nagariensis. Therefore, the minimum ratio of somatic cells to androgonidia in male spheroids and the maximum number of gonidia in asexual spheroids may be diagnostic for V. carteri f. nagariensis. HMG1f may not be directly related to the formation of female spheroids in this taxon

Changes in the quality of diabetes care in Japan between 2007 and 2015: A repeated cross-sectional study using claims data

AimTo assess the temporal changes in the quality indicators pertaining to the process measures of diabetes care during a recent decade in Japan.MethodsA five-fold repeated cross-sectional study was conducted using health insurance claims data provided by the Japan Medical Data Center between April 2006 and March 2016. We identified 46,631 outpatients with antidiabetic medication who regularly visited hospitals or clinics at least every three months. We evaluated the quality indicators pertaining to glycemic control monitoring, lipid profile monitoring, retinopathy screening, nephropathy screening, and appropriate medication choice. The proportions of patients who received appropriate examinations/prescriptions, by observation period and either the type of antidiabetic medication or facility type were estimated using generalized estimating equation (GEE) models with multiple covariate adjustments.ResultsThe quality indicator values for appropriate medication choice and nephropathy screening improved between 2007 and 2015, whereas those for glycemic control monitoring and retinopathy screening remained suboptimal. Patients prescribed medications in larger hospitals were likelier to undergo the recommended examinations (e.g. retinopathy screening: 36.1% (95% CI: 35.4–36.7%) for clinic, 40.6% (95% CI: 39.1–42.2%) for smaller hospital, and 46.0% (95% CI: 44.8–47.2%) for larger hospital in 2015).ConclusionsSeveral process measures of diabetes care remained suboptimal in Japan

Significance of measurement of tumor marker in primary breast cancer

We investigated a prognosis in the presence or absence of preoperative marker abnormality for 371 cases with primary breast cancer that we experienced in our department this time. 60 (16%) of 371 cases showed the abnormality of the tumor marker and 25 (41.7%) of 60 patients had a recurrence. The positive rate of the marker was 8.1% in CA 15 3, 6.7% in CEA, 4.1% in NCC ST 439, and each rate of recurrence was 56.7%, 48.0%, 33.3%. Rate of recurrence in the negative cases was 12.7%, 13.9, 15.0% respectively and recognized a significant difference statistically (p <0.001) . Of 11 cases (3.8%) shown CA 15 3 abnormal high level, 3 cases (27.2%) had recurrence when we examined in 0 3 metastases to lymph nodes according to markers. 281 cases (96.2%) was normal range in CA15 3. Only 15 cases (5%) had recurrence. It showed a significant difference statistically (p <0.05) . For the cases shown abnormality of the preoperative CA 15 3, careful serial observations are necessary

母親が認識した携帯用アドレナリン自己注射薬を所持する重症食物アレルギー児の幼児期における心理社会的問題と実施した対応策

This study aimed to clarify mothers\u27 perceptions about psychosocial issues and solutions in preschool-age foodallergic children (FA children) who need to carry adrenaline auto-injector (Epipen®). Semi-structured interviews were conducted with eight mothers of FA children, which were analyzed qualitatively and descriptively. The problems perceived by mothers were: situations that only FA children have to deal with; lack of experience with food; negative feelings about the allergy-inducing food; immaturity of judgment about allergies; and difficulty in transitioning to the stage of separation from parents. The mothers\u27 proposed solutions were: setting scenes to foster food experiences that are led by the FA child; adjusting the environment for shared experiences with other children; empathy for the feelings of FA children; preparing allergen-free elimination diet menus when going out; responding to a dietary therapy that considers the feelings of FA children; education to improve FA children’s self-care ability for allergies; and working to be understood by adults involved with FA children outside the home regarding food allergies.　母親が認識した携帯用アドレナリン自己注射薬を所持する重症食物アレルギー児の幼児期における心理社会的問題と母親が実施した対応策を明らかにすることを目的に、FA 児の母親8 名に半構成面接を行い、質的記述的に分析した。母親は、FA 児の幼児期の心理社会的問題として、【FA 児だけが我慢しなければならない状況】【食を通した体験の不足】【原因食物に対するネガティブな感情】【アレルギーに関する判断の未熟さ】【親元から離れる段階への移行が困難な状況】を認識していた。それらの問題に対して、【食への主体性を育める場面の設定】【他児と体験が共有できる環境の調整】【FA 児の気持ちへの共感】【外出時にアレルギー対応食を食べさせる準備】【FA 児の気持ちに配慮した食事療法への対応】【アレルギーに対するセルフケア能力の向上を目指した教育】【家庭外でFA 児に関わる大人に理解を得るための働きかけ】を有効な対応策として実施していた