Is cardiorespiratory fitness associated with cognitive outcomes in mid-adulthood? Findings from the 1958 British birth cohort.

Identifying causal factors to intervene on to delay age-related declines in cognitive function is urgently needed. We examined associations between non-exercise testing cardiorespiratory fitness (NETCRF; estimated using sex, age, body mass index, resting heart rate, and physical activity) at 45 years and cognitive function outcomes (immediate and delayed verbal memory; verbal fluency; visual processing speed) at 50 years in 8130 participants from the 1958 British birth cohort. In unadjusted models, higher NETCRF was associated with better cognitive function across all outcomes. When adjusted for confounding factors, associations disappeared. In this cohort, associations between 45 years NETCRF and 50 years cognitive function likely result from confounding factors.

Associations between diabetes status and grip strength trajectory sub-groups in adulthood: findings from over 16 years of follow-up in the MRC National Survey of Health and Development.

BACKGROUND: Cross-sectional studies suggest a relationship between diabetes status and weaker grip strength (GS) in adulthood and limited evidence from longitudinal studies has focussed on the association with average change in GS. We aimed to investigate whether diabetes status was related to membership of distinct GS trajectories in mid-to-late adulthood in 2,263 participants in the Medical Research Council National Survey of Health and Development. METHODS: Grip strength (kg) was measured at 53, 60-64 and 69 years. Pre-/diabetes was defined at 53 years based on HbA1c > 5.6% and/or doctor-diagnosis of diabetes. Sex-specific latent class trajectory models were developed and multinomial logistic regression was used to investigate the association between pre-/diabetes status and membership into GS trajectory classes. RESULTS: For both males and females, a 3-class solution ('High', 'Intermediate', 'Low') provided the best representation of the GS data and the most plausible solution. There was no evidence that pre-/diabetes status was associated with class membership in either sex: e.g., adjusted odds ratios of being in the 'Low' class (vs. 'High') for males with pre-/diabetes (vs. no-diabetes) was 1.07 (95% CI:0.45,2.55). CONCLUSION: Using a flexible data-driven approach to identify GS trajectories between 53 and 69 years, we observed three distinct GS trajectories, all declining, in both sexes. There was no association between pre-/diabetes status at 53 years and membership into these GS trajectories. Understanding the diabetes status-GS trajectories association is vital to ascertain the consequences that projected increases in pre-/diabetes prevalence's are likely to have.

Defining the Optimal Treatment Strategy in Patients With Uterine Serous Carcinoma.

AIMS: Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer with high rates of relapse and death. As adjuvant therapy might be beneficial in early-stage disease, the impact of standard complete surgical staging is questioned. Therefore, we wanted to explore the optimal treatment strategy for women diagnosed with USC. MATERIALS AND METHODS: A retrospective multicentre study of women diagnosed with primary USC in the UK and the Netherlands. Treatment strategy in relation to overall survival and progression-free survival was recorded and evaluated with Kaplan-Meier and Cox regression analysis. Furthermore, primary surgical staging and/or adjuvant treatment in relation to patterns of recurrence were evaluated. RESULTS: In total, 272 women with a median age of 70 years were included. Most patients presented with International Federation of Gynecology and Obstetrics (FIGO) stage I disease (44%). Overall, 48% of patients developed recurrent disease, most (58%) with a distant component. Women treated with chemotherapy showed significantly better overall survival (hazard ratio 0.50, 95% confidence interval 0.31-0.81; P = 0.005) and progression-free survival (hazard ratio 0.48, 95% confidence interval 0.28-0.80; P = 0.04) in multivariable analysis. Furthermore, even in surgically staged women with FIGO stage IA disease, a high recurrence rate of 42% was seen. CONCLUSION: Women with USC who received adjuvant chemotherapy showed better survival rates compared with those who received other or no adjuvant treatment. The benefit of adjuvant chemotherapy was observed across all tumour stages, including surgically staged FIGO stage IA. These data question the role of surgical staging in the absence of macroscopic disease in USC.

Obesity in early adulthood and physical functioning in mid-life: Investigating the mediating role of c-reactive protein.

INTRODUCTION: Obesity in adulthood is associated with reduced physical functioning (PF) at older ages. However, mechanisms underpinning this association are not well understood. We investigated whether and the extent to which C-reactive protein (CRP) mediates the association between early-adult obesity and mid-life PF. METHODS: We used data from 8495 participants in the 1958 British birth cohort study. Body mass index (BMI), CRP and PF were measured at 33, 45 and 50y, respectively. Poor PF was defined as the lowest (sex-specific) 10% on the Short-form 36 Physical Functioning subscale. We accounted for prospectively measured confounders in early-life (e.g., social class at birth) and in mid-adulthood (e.g., 42y comorbidities). We decomposed the total effect of early-adult obesity on mid-life PF into direct and indirect (via CRP) effects, by employing a mediation analysis based on parametric g-computation. RESULTS: The estimated total effect of obesity at 33y on poor PF at 50y, expressed as an odds ratio (OR), was 2.41 (95% CI: 1.89, 3.08). The direct effect of obesity on poor PF (i.e., not operating via CRP), was 1.97 (95% CI: 1.51, 2.56), with an indirect effect of 1.23 (95% CI: 1.10, 1.37). As such, the proportion of the total effect which was mediated by the effect of obesity on CRP at 45y, was 23.27% (95% CI: 8.64%, 37.90%). CONCLUSION: Obesity in early-adulthood was associated with over twice the odds of poor PF in mid-life, with approximately 23% of the obesity effect operating via a downstream effect on CRP. As current younger generations are likely to spend greater proportions of their life course in older age and with obesity, both of which are associated with poor PF, there is an urgent need to identify mechanisms, and thus potential modifiable intermediaries, linking obesity to poor PF.

Changes over time in latent patterns of childhood-to-adulthood BMI development in Great Britain: evidence from three cohorts born in 1946, 1958, and 1970.

BACKGROUND: Most studies on secular trends in body mass index (BMI) are cross-sectional and the few longitudinal studies have typically only investigated changes over time in mean BMI trajectories. We aimed to describe how the evolution of the obesity epidemic in Great Britain reflects shifts in the proportion of the population demonstrating different latent patterns of childhood-to-adulthood BMI development. METHODS: We used pooled serial BMI data from 25,655 participants in three British cohorts: the 1946 National Survey of Health and Development (NSHD), 1958 National Child Development Study (NCDS), and 1970 British Cohort Study (BCS). Sex-specific growth mixture models captured latent patterns of BMI development between 11 and 42 years. The classes were characterised in terms of their birth cohort composition. RESULTS: The best models had four classes, broadly similar for both sexes. The 'lowest' class (57% of males; 47% of females) represents the normal weight sub-population, the 'middle' class (16%; 15%) represents the sub-population who likely develop overweight in early/mid-adulthood, and the 'highest' class (6%; 9%) represents those who likely develop obesity in early/mid-adulthood. The remaining class (21%; 29%) reflects a sub-population with rapidly 'increasing' BMI between 11 and 42 years. Both sexes in the 1958 NCDS had greater odds of being in the 'highest' class compared to their peers in the 1946 NSHD but did not have greater odds of being in the 'increasing' class. Conversely, males and females in the 1970 BCS had 2.78 (2.15, 3.60) and 1.87 (1.53, 2.28), respectively, times higher odds of being in the 'increasing' class. CONCLUSIONS: Our results suggest that the obesity epidemic in Great Britain reflects not only an upward shift in BMI trajectories but also a more recent increase in the number of individuals demonstrating more rapid weight gain, from normal weight to overweight, across the second, third, and fourth decades of life.

Quality control of ultrasound for fetal biometry: results from the INTERGROWTH-21st Project.

OBJECTIVE: To assess a comprehensive package of ultrasound quality control in the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project, a large multicenter study of fetal growth. METHODS: Quality control (QC) measures were performed for 20 313 ultrasound scan images obtained prospectively from 4321 fetuses at 14-41 weeks' gestation in eight geographical locations. At the time of each ultrasound examination, three fetal biometric variables (head circumference (HC), abdominal circumference (AC) and femur length (FL)) were measured in triplicate on separately generated images. All measurements were taken in a blinded fashion. QC had two elements: (1) qualitative QC: visual assessment by sonographers at each study site of their images based on specific criteria, with 10% of images being re-assessed at the Oxford-based Ultrasound Quality Unit (compared using an adjusted kappa statistic); and (2) quantitative QC: assessment of measurement data by comparing the first, second and third measurements (intraobserver variability), remeasurement of caliper replacement in 10% (interobserver variability), both by Bland-Altman plots and plotting frequency histograms of the SD of triplicate measurements and assessing how many were above or below 2 SD of the expected distribution. The system allowed the sonographers' performances to be monitored regularly. RESULTS: A high level of agreement between self- and external scoring was demonstrated for all measurements (κ = 0.99 (95% CI, 0.98-0.99) for HC, 0.98 (95% CI, 0.97-0.99) for AC and 0.96 (95% CI, 0.95-0.98) for FL). Intraobserver 95% limits of agreement (LoA) of ultrasound measures for HC, AC and FL were ± 3.3%, ± 5.6% and ± 6.2%, respectively; the corresponding values for interobserver LoA were ± 4.4%, ± 6.0% and ± 5.6%. The SD distribution of triplicate measurements for all biometric variables showed excessive variability for three of 31 sonographers, allowing prompt identification and retraining. CONCLUSIONS: Qualitative and quantitative QC monitoring was feasible and highly reproducible in a large multicenter research study, which facilitated the production of high-quality ultrasound images. We recommend that the QC system we developed is implemented in future research studies and clinical practice. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

"Shaped" humeral head autograft reverse shoulder arthroplasty : Treatment for primary glenohumeral osteoarthritis with significant posterior glenoid bone loss (B2, B3, and C type).

BACKGROUND: Posterior glenoid bone loss in primary glenohumeral osteoarthritis (GHOA) presents a challenge when considering replacement surgery. Results with anatomic shoulder arthroplasty are unpredictable due to posterior humeral instability and limited bone stock for glenoid component fixation. OBJECTIVES: To describe and evaluate the results of a "shaped" humeral head autograft with reverse shoulder arthroplasty (RSA) for the treatment of primary GHOA with significant posterior glenoid bone loss and an intact, functional rotator cuff. MATERIALS AND METHODS: We retrospectively reviewed 29 "shaped" humeral head autografts with RSA for the treatment of GHOA with B2 (n = 16), B3 (n = 10), or C (n = 3) glenoid morphology based on the Walch classification system. Average glenoid retroversion was 32.3°. Humeral head autografts were "shaped" to match each patient's individual glenoid morphology. Functional outcome scores, range of motion, strength, and radiographic outcomes were evaluated. RESULTS: At average follow-up of 34.6 months (range 23.7-88.9 months), significant improvements were seen in all functional outcome scores, ranges of motion, and strength (p <0.01). No recurrent instability or glenoid fixation failure occurred. Two complications (1 superficial and 1 deep infection) in 2 patients were identified. All autografts incorporated without radiographic evidence of loosening. Scapular notching was observed in 8 shoulders. No negative correlations were identified with glenoid morphology. CONCLUSIONS: "Shaped" humeral head autograft with RSA for the treatment of primary GHOA with significant posterior glenoid bone loss is associated with excellent clinical and radiographic outcomes and a low complication profile at short- to mid-term follow-up.

Revision shoulder arthroplasty with a reverse shoulder prosthesis : Use of structural allograft for glenoid bone loss.

INTRODUCTION: Revision shoulder arthroplasty presents many unique and complex challenges when glenoid bone loss is involved. A distorted and medialized anatomy prevents the proper mechanics of the reverse prosthesis with regard to deltoid tension and ultimate function. This paper highlights one surgeon's experience using structural allograft for glenoid bone loss. PATIENTS AND METHODS: In all, 20 patients for a total of 24 surgeries with a medialized glenoid and/or substantial glenoid bone loss of grade IIB or higher were evaluated in this retrospective study. The allograft surgeries were performed as a one-stage procedure except for three patients. Recombinant human bone morphogenetic protein-2 (BMP2) was added to supplement incorporation in all cases. Four patients had two separate allograft procedures. Eight of the allograft procedure were femoral shaft, eleven of the allografts were femoral neck/head, and five of the allograft procedures were from proximal humerus. A graft was considered a success if they had at least 12 months of clinical and radiographic follow-up without subsequent removal of the graft or radiographic failure. Patients with less than 12 months of follow-up were included if the graft was removed or had early failure. RESULTS: All femoral shaft allografts except one failed, and during revision surgery it was often noted that the graft was cracked where the peripheral screws had been drilled. In nine patients the graft was still in place at last follow-up, seven of these were femoral neck/head allografts. Five grafts were removed secondary to infection. Average follow-up was 24 months (range 5-45 months). CONCLUSIONS: Femoral neck allografts are an option in patients with substantial bone loss. The authors do not recommend use of femoral shaft allografts.

Obesity in adolescents with chronic fatigue syndrome: an observational study.

OBJECTIVE: Identify the prevalence of obesity in patients with chronic fatigue syndrome (CFS) compared with healthy adolescents, and those identified with CFS in a population cohort. DESIGN: Cross-sectional analysis of multiple imputed data. SETTING: Data from UK paediatric CFS/myalgic encephalomyelitis (CFS/ME) services compared with data collected at two time points in the Avon Longitudinal Study of Parents and Children (ALSPAC). PATIENTS: 1685 adolescents who attended a CFS/ME specialist service between 2004 and 2014 and 13 978 adolescents aged approximately 13 years and 16 years participating in the ALSPAC study. MAIN OUTCOME MEASURES: Body mass index (BMI) (kg/m2), sex-specific and age-specific BMI Z-scores (relative to the International Obesity Task Force cut-offs) and prevalence of obesity (%). RESULTS: Adolescents who had attended specialist CFS/ME services had a higher prevalence of obesity (age 13 years: 9.28%; age 16 years: 16.43%) compared with both adolescents classified as CFS/ME in ALSPAC (age 13 years: 3.72%; age 16 years: 5.46%) and those non-CFS in ALSPAC (age 13 years: 4.18%; age 16 years: 4.46%). The increased odds of obesity in those who attended specialist services (relative to non-CFS in ALSPAC) was apparent at both 13 years (OR: 2.31 (1.54 to 3.48)) and 16 years, with a greater likelihood observed at 16 years (OR: 4.07 (2.04 to 8.11)). CONCLUSIONS: We observed an increased prevalence of obesity in adolescents who were affected severely enough to be referred to a specialist CFS/ME service. Further longitudinal research is required in order to identify the temporal relationship between the two conditions.

Scientific basis for standardization of fetal head measurements by ultrasound: a reproducibility study.

OBJECTIVE: To compare the standard methods for ultrasound measurement of fetal head circumference (HC) and biparietal diameter (BPD) (outer-to-outer (BPDoo) vs outer-to-inner (BPDoi) caliper placement), and compare acquisition of these measurements in transthalamic (TT) vs transventricular (TV) planes. METHODS: This study utilized ultrasound images acquired from women participating in the Oxford arm of the INTERGROWTH-21(st) Project. In the first phase of the study, BPDoo and BPDoi were measured on stored images. In the second phase, real-time measurements of BPD, occipitofrontal diameter (OFD) and HC in TT and TV planes were obtained by pairs of sonographers. Reproducibility of measurements made by the same (intraobserver) and by different (interobserver) sonographers, as well as the reproducibility of caliper placement and measurements obtained in different planes, was assessed using Bland-Altman plots. RESULTS: In Phase I, we analyzed ultrasound images of 108 singleton fetuses. The mean intraobserver and interobserver differences were < 2% (1.34 mm) and the 95% limits of agreement were < 5% (3 mm) for both BPDoo and BPDoi. Neither method for measuring BPD showed consistently better reproducibility. In Phase II, we analyzed ultrasound images of 100 different singleton fetuses. The mean intraobserver and interobserver differences were < 1% (2.26 mm) and the 95% limits of agreement were < 8% (14.45 mm) for all fetal head measurements obtained in TV and TT planes. Neither plane for measuring fetal head showed consistently better reproducibility. Measurement of HC using the ellipse facility was as reproducible as HC calculated from BPD and OFD. OFD by itself was the least reproducible of all fetal head measurements. CONCLUSIONS: Measurements of BPDoi and BPDoo are equally reproducible; however, we believe BPDoo should be used in clinical practice as it allows fetal HC to be measured and compared with neonatal HC. For all head measurements, TV and TT planes provide equally reproducible values at any gestational age, and HC values are similar in both planes. Fetal head measurement in the TT plane is preferable as international standards in this plane are available; however, measurements in the TV plane can be plotted on the same standards. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Colonoscopy in rural communities: a systematic review of the frequency and quality.

INTRODUCTION: In this systematic review, the authors review studies of rural colonoscopy to determine specialty types providing rural colonoscopy and the quality of these procedures. METHODS: A systematic MEDLINE search was conducted for articles pertaining to rural colonoscopy. Inclusion criteria were rural location, report of quality outcomes, or report of endoscopy workforce in rural areas. Two investigators independently reviewed and abstracted included articles. The following information was obtained from each study: author identification, citation, study design, source of funding, study duration and follow-up, study population, sample size, study setting, population characteristics, outcomes and results. Standard abstraction forms were used to summarize and assess the quality of evidence. RESULTS: From 121 articles in the MEDLINE search, 11 met inclusion criteria. One additional article found from a reference list was included. Eleven articles from three countries reported on 8703 colonoscopies performed by 25 rural generalists. Reach-the-cecum rates (RCR) ranged from 36% to 96.5% with more recent studies showing higher RCRs. Adenoma detection rates ranged from 16.6% to 46%. The rate of complications was low in all studies. One study of the rural endoscopist workforce reported that general surgeons performed most rural colonoscopies in Canada. CONCLUSIONS: Rural generalist physicians can safely and effectively perform colonoscopies. More research is needed on the rural endoscopist workforce.

Small-for-gestational age and large-for-gestational age thresholds to predict infants at risk of adverse delivery and neonatal outcomes: are current charts adequate? An observational study from the Born in Bradford cohort.

OBJECTIVES: Construct an ethnic-specific chart and compare the prediction of adverse outcomes using this chart with the clinically recommended UK-WHO and customised birth weight charts using cut-offs for small-for-gestational age (SGA: birth weight <10th centile) and large-for-gestational age (LGA: birth weight >90th centile). DESIGN: Prospective cohort study. SETTING: Born in Bradford (BiB) study, UK. PARTICIPANTS: 3980 White British and 4448 Pakistani infants with complete data for gestational age, birth weight, ethnicity, maternal height, weight and parity. MAIN OUTCOME MEASURES: Prevalence of SGA and LGA, using the three charts and indicators of diagnostic utility (sensitivity, specificity and area under the receiver operating characteristic (AUROC)) of these chart-specific cut-offs to predict delivery and neonatal outcomes and a composite outcome. RESULTS: In White British and Pakistani infants, the prevalence of SGA and LGA differed depending on the chart used. Increased risk of SGA was observed when using the UK-WHO and customised charts as opposed to the ethnic-specific chart, while the opposite was apparent when classifying LGA infants. However, the predictive utility of all three charts to identify adverse clinical outcomes was poor, with only the prediction of shoulder dystocia achieving an AUROC>0.62 on all three charts. CONCLUSIONS: Despite being recommended in national clinical guidelines, the UK-WHO and customised birth weight charts perform poorly at identifying infants at risk of adverse neonatal outcomes. Being small or large may increase the risk of an adverse outcome; however, size alone is not sensitive or specific enough with current detection to be useful. However, a significant amount of missing data for some of the outcomes may have limited the power needed to determine true associations.

Terahertz generation by dynamical photon drag effect in graphene excited by femtosecond optical pulses.

Graphene has been proposed as a particularly attractive material for the achievement of strong optical nonlinearities, in particular generation of terahertz radiation. However, owing to the particular symmetries of the C-lattice, second-order nonlinear effects such as difference-frequency or rectification processes are predicted to vanish in a graphene layer for optical excitations (ℏω ≫ 2EF) involving the two relativistic dispersion bands. Here we experimentally demonstrate that graphene excited by femtosecond optical pulses generate a coherent THz radiation ranging from 0.1 to 4 THz via a second-order nonlinear effect. We fully interpret its characteristics with a model describing the electron and hole states beyond the usual massless relativistic scheme. This second-order nonlinear effect is dynamical photon drag, which relies on the transfer of light momentum to the carriers by the ponderomotive electric and magnetic forces. The model highlights the key roles of next-C-neighbor couplings and of unequal electron and hole lifetimes in the observed second-order response. Finally, our results indicate that dynamical photon drag effect in graphene can provide emission up to 60 THz, opening new routes for the generation of ultrabroadband terahertz pulses.

Toward parametric amplification in plasmonic systems: second harmonic generation enhanced by surface plasmon polaritons.

Having in mind parametric amplification of surface plasmon polaritons (SPPs) as the final goal, we took the first step and studied in the Kretschmann geometry a simpler nonlinear optical process - second harmonic generation (SHG) enhanced by SPPs propagating at the interface between gold film and 2-methyl-4-nitroaniline (MNA). The experimentally demonstrated SHG efficiency was nearly 10(6) times larger than the one reported previously in the SPP system with different nonlinear optical material. The experimentally measured nonlinear conversion efficiency is estimated to be sufficient for parametric amplification of surface plasmon polaritons at ultra-short laser pumping.

Investigating the relationship between prenatal growth and postnatal outcomes: a systematic review of the literature.

Theories regarding the relationship between pre- and postnatal growth and programming of health have been based on characteristics at birth, with little or no reference to the patterns of growth occurring in utero. Review of the literature to identify studies using ultrasonographically obtained fetal dimensions to track prenatal growth and relate these patterns of growth to postnatal anthropometry and cardiovascular and metabolic risk factors. Review of Medline, Scopus and Proquest for studies reporting on ultrasonographically derived estimates of fetal growth and their association with postnatal anthropometry, body composition or cardiovascular and metabolic risk factors. Quality of papers were assessed using the method developed by Downs and Black. Twenty-nine studies met the inclusion criteria, with a mean score of high quality. Twenty of the studies had follow-up in infancy, five in childhood, three in adolescence and one in adulthood. The associations observed suggest that centile tracking may occur early in pregnancy though whether this is as early as the first trimester is uncertain. The second trimester may be a critical period for the programming of blood pressure and abdominal circumference may be the most sensitive fetal dimension to indicate any programming.

Repeatability of subjective evaluation of lameness in horses.

REASONS FOR PERFORMING STUDY: Previous studies have suggested that agreement between equine veterinarians subjectively evaluating lameness in horses is low. These studies were limited to small numbers of horses, evaluating movement on the treadmill or to evaluating previously-recorded videotape. OBJECTIVES: To estimate agreement between equine practitioners performing lameness evaluations in horses in the live, over ground setting. METHODS: 131 mature horses were evaluated for lameness by 2-5 clinicians (mean 3.2) with a weighted-average of 18.7 years of experience. Clinicians graded each limb using the AAEP lameness scale by first watching the horse trot in a straight line only and then after full lameness evaluation. Agreement was estimated by calculation of Fleiss' (kappa). Evaluators agreed if they picked the same limb as lame or not lame regardless of the severity of perceived lameness. RESULTS: After only evaluating the horse trot in a straight line clinicians agreed whether a limb was lame or not 76.6% of the time (kappa= 0.44). After full lameness evaluation clinicians agreed whether a limb was lame or not 72.9% of the time (kappa= 0.45). Agreement on forelimb lameness was slightly higher than on hindlimb lameness. When the mean AAEP lameness score was >1.5 clinicians agreed whether or not a limb was lame 93.1% of the time (kappa= 0.86), but when the mean score was < or = 1.5 they agreed 61.9% (kappa= 0.23) of the time. When given the task of picking whether or not the horse was lame and picking the worst limb after full lameness evaluation, clinicians agreed 51.6% (kappa= 0.37) of the time. CONCLUSIONS: For horses with mild lameness subjective evaluation of lameness is not very reliable. POTENTIAL RELEVANCE: A search for and the development of more objective and reliable methods of lameness evaluation is justified and should be encouraged and supported.

Biogeographic and phylogenetic diversity of thermoacidophilic cyanidiales in Yellowstone National Park, Japan, and New Zealand.

Members of the rhodophytan order Cyanidiales are unique among phototrophs in their ability to live in extreme environments that combine low pH levels ( approximately 0.2 to 4.0) and moderately high temperatures of 40 to 56 degrees C. These unicellular algae occur in far-flung volcanic areas throughout the earth. Three genera (Cyanidium, Galdieria, and Cyanidioschyzon) are recognized. The phylogenetic diversity of culture isolates of the Cyanidiales from habitats throughout Yellowstone National Park (YNP), three areas in Japan, and seven regions in New Zealand was examined by using the chloroplast RuBisCO large subunit gene (rbcL) and the 18S rRNA gene. Based on the nucleotide sequences of both genes, the YNP isolates fall into two groups, one with high identity to Galdieria sulphuraria (type II) and another that is by far the most common and extensively distributed Yellowstone type (type IA). The latter is a spherical, walled cell that reproduces by internal divisions, with a subsequent release of smaller daughter cells. This type, nevertheless, shows a 99 to 100% identity to Cyanidioschyzon merolae (type IB), which lacks a wall, divides by "fission"-like cytokinesis into two daughter cells, and has less than 5% of the cell volume of type IA. The evolutionary and taxonomic ramifications of this disparity are discussed. Although the 18S rRNA and rbcL genes did not reveal diversity among the numerous isolates of type IA, chloroplast short sequence repeats did show some variation by location within YNP. In contrast, Japanese and New Zealand strains showed considerable diversity when we examined only the sequences of 18S and rbcL genes. Most exhibited identities closer to Galdieria maxima than to other strains, but these identities were commonly as low as 91 to 93%. Some of these Japanese and New Zealand strains probably represent undescribed species that diverged after long-term geographic isolation.

Chromosomes of tuatara, Sphenodon, a chromosome heteromorphism and an archaic reptilian karyotype.

We examined karyotypes of the endemic New Zealand reptile genus Sphenodon (tuatara) from five populations, finding a karyotype unchanged for at least one million years. Animals karyotyped were from five geographically distinct populations, representing three groups, namely S. guntheri, S. punctatus (Cook Strait group), and S. punctatus (northeastern North Island group). All five populations have a diploid chromosome number of 2n = 36, consisting of 14 pairs of macrochromosomes and four pairs of microchromosomes. Chromosomal differences were not found between the five populations nor between female and male animals, except for one animal with a structural heteromorphism. Similarity between Sphenodon and Testudine karyotypes suggests an ancestral karyotype with a macrochromosome complement of 14 pairs and the ability to accumulate variable numbers of microchromosome pairs. Our research supports molecular phylogenies of the Reptilia.