Evaluating Osteoarthritis Management Programs: outcome domain recommendations from the OARSI Joint Effort Initiative

OBJECTIVE

To develop sets of core and optional recommended domains for describing and evaluating Osteoarthritis Management Programs (OAMPs), with a focus on hip and knee Osteoarthritis (OA).

DESIGN

We conducted a 3-round modified Delphi survey involving an international group of researchers, health professionals, health administrators and people with OA. In Round 1, participants ranked the importance of 75 outcome and descriptive domains in five categories: patient impacts, implementation outcomes, and characteristics of the OAMP and its participants and clinicians. Domains ranked as "important" or "essential" by ≥80% of participants were retained, and participants could suggest additional domains. In Round 2, participants rated their level of agreement that each domain was essential for evaluating OAMPs: 0 = strongly disagree to 10 = strongly agree. A domain was retained if ≥80% rated it ≥6. In Round 3, participants rated remaining domains using same scale as in Round 2; a domain was recommended as "core" if ≥80% of participants rated it ≥9 and as "optional" if ≥80% rated it ≥7.

RESULTS

A total of 178 individuals from 26 countries participated; 85 completed all survey rounds. Only one domain, "ability to participate in daily activities", met criteria for a core domain; 25 domains met criteria for an optional recommendation: 8 Patient Impacts, 5 Implementation Outcomes, 5 Participant Characteristics, 3 OAMP Characteristics and 4 Clinician Characteristics.

CONCLUSION

The ability of patients with OA to participate in daily activities should be evaluated in all OAMPs. Teams evaluating OAMPs should consider including domains from the optional recommended set, with representation from all five categories and based on stakeholder priorities in their local context.

The patient enablement instrument for back pain: reliability, content validity, construct validity and responsiveness

Background

Currently, there are no outcome measures assessing the ability of people with non-specific low back pain to self-manage their illness. Inspired by the ‘Patient Enablement Instrument’, we developed the Patient Enablement Instrument for Back Pain (PEI-BP). The aim of this study was to describe the development of the Patient Enablement Instrument for Back Pain (PEI-BP) and investigate content validity, construct validity, internal consistency, test–retest reliability, measurement error, responsiveness and floor and ceiling effects.

Methods

The PEI-BP consists of 6 items that are rated on a 0–10 Numeric Rating Scale. Measurement properties were evaluated using the COSMIN taxonomy and were based on three cohorts from primary care with low back pain: The content validity cohort (N = 14) which participated in semi-structured interviews, the GLA:D® Back cohort (N = 272) and the test–retest cohort (N = 37) which both completed self-reported questionnaires. For construct validity and responsiveness, enablement was compared to disability (Oswestry Disability Index), back pain beliefs (Brief Illness Perception Questionnaire), fear avoidance (Fear-Avoidance Beliefs Questionnaire—physical activity), mental health (SF-36), educational level and number of previous episodes of low back pain.

Results

The PEI-BP was found to have acceptable content validity, construct validity, reliability (internal consistency, test–retest reliability and measurement error) and responsiveness. The Smallest Detectable Change was 10.1 points illustrating that a patient would have to change more than 1/6 of the scale range for it to be a true change. A skewed distribution towards the high scores were found at baseline indicating a potentially problematic ceiling effect in the current population.

Conclusions

The PEI-BP can be considered a valid and reliable tool to measure enablement on people seeking care for non-specific LBP. Further testing of the PEI-BP in populations with more severe LBP is recommended.

Trial registration: Not applicable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12955-021-01758-0.

Advances in 211At production at Texas A&M University

Alpha emitting radionuclides with medically relevant half-lives are interesting for treatment of tumors and other diseases because they deposit large amounts of energy close to the location of the radioisotope. Researchers at the Cyclotron Institute at Texas A&M University are developing a program to produce 211At, an alpha emitter with a medically relevant half-life. The properties of 211At make it a great candidate for targeted alpha therapy for cancer due to its short half-life (7.2 h). Astatine-211 has now been produced multiple times and reliability of this process is being improved.

Centralized Clinical Trial Imaging Data Management: Practical Guidance from a Comprehensive Cancer Center's Experience

Medical imaging is an integral part of clinical trial research and it must be managed properly to provide accurate data to the sponsor in a timely manner (Clune in Cancer Inform 4:33-56, 2007; Wang et al. in Proc SPIE Int Soc Opt Eng 7967, 2011). Standardized workflows for site qualification, protocol preparation, data storage, retrieval, de-identification, submission, and query resolution are paramount to achieve quality clinical trial data management such as reducing the number of imaging protocol deviations and avoiding delays in data transfer. Centralization of data management and implementation of relational databases and electronic workflows can help maintain consistency and accuracy of imaging data. This technical note aims at sharing the practical implementation of our centralized clinical trial imaging data management processes to avoid the fragmentation of tasks among various disease centers and research staff, and enable us to provide quality, accurate, and timely imaging data to clinical trial sponsors.

Diabetic foot ulcer incidence and survival with improved diabetic foot services: an 18-year study

AIMS

To ascertain the effects of improvements in diabetic foot services over 18 years on incidence of diabetic foot ulceration. We also compared survival time from first ulcer development with presence of neuropathy, peripheral vascular disease, age and healing.

METHODS

Persons with new ulceration and those at high risk of ulcer development were referred to community podiatry from 1998. Their details were recorded, with verbal consent, on a central database. The effects of neuropathy, peripheral vascular disease, healing and age on survival were analysed by Cox proportional hazards ratios.

RESULTS

The incidence of first ulcer presentation decreased from 11.1 to 6.1 per 1000 persons between 2003 to 2017 (P <0.0001). Recurrent ulceration incidence remained stable. Prevalence of chronic and new foot ulceration combined increased from 20.7 to 33.1 per 1000 persons (P <0.0001). Ten-year survival was 85% for persons presenting with first ulcer and aged < 65 years, 50% for those aged 65-74 years and 25% for those aged 75-81 years (P < 0.0001). In those with peripheral vascular disease 5-year survival was 35% (P <0.001).

CONCLUSIONS

Integrated care for the diabetic foot in one National Health Service (NHS) health service area over 18 years was associated with a reduction in first presentations of diabetic foot ulceration, but failed to reduce recurrent ulceration. Cumulative prevalence of all ulcers continues to increase. Monitoring ulceration incidence can inform audit and planning of diabetic foot care services. Survival is better than reported previously in persons < 65 years and in the absence of peripheral vascular disease.

Diabetes-related major lower limb amputation incidence is strongly related to diabetic foot service provision and improves with enhancement of services: peer review of the South-West of England

AIMS

To investigate the relationship between high diabetes-related lower limb amputation incidence and foot care services in the South-West region of England.

METHODS

The introduction of 10 key elements of foot care service provision in one area of the South-West resulted in stabilization of foot ulcer incidence and sustained reduction in amputation incidence from 2007. Services introduced included administrative support, standardized general practice foot screening, improved community podiatry staffing, hospital multidisciplinary foot clinics, effective care pathways, availability of an orthotist and audit. Peer reviews of the region's diabetes foot care services were undertaken to assess delivery of these service provisions and compare this with major amputation incidence in other regions with data provided by Yorkshire and Humber Public Health Observatory Hospital Episode Statistics. Recommendations were made to improve service provision. In 2015 changes in service provision and amputation incidence were reviewed.

RESULTS

Initial reviews in 2013 showed that the 3-year diabetes-related major amputation incidence correlated inversely with adequate delivery of diabetes foot care services (P=0.0024, adjusted R² =0.51). Repeat reviews in 2015 found that two or more foot care service improvements were reported by six diabetes foot care providers, with improvement in outcomes. The negative relationship between major amputation incidence and service provision remained strong both in the period 2012-2015 and in the year 2015 only (P ≤0.0012, adjusted R² =0.56, and P= 0.0005, R² =0.62, respectively).

CONCLUSIONS

Major diabetes-related lower limb amputation incidence is significantly inversely correlated with foot care services provision. Introduction of more effective service provision resulted in significant reductions in major amputation incidence within 2 years. Failure to improve unsatisfactory service provision resulted in continued high amputation incidence.

Implementing an electronic clinical handover system in a university teaching hospital

INTRODUCTION

Clinical handover is defined as inter-clinician communication occurring at care interfaces. In this study, we analyse the clinical outcomes and physician attitudes associated with the implementation of a electronic clinical handover system in our medical department.

AIM

The aim of this project was to introduce a reliable, standardised, reproducible method of communicating information regarding inpatients within our medical department. We also sought to assess the attitudes of physicians within our department to medical handover.

METHODS

We designed and implemented an electronic handover template with a protocol to guide staff as to its use. Handover was audited weekly. In addition, we surveyed attitudes of doctors to handover before and after our handover pilot.

RESULTS

An average of 32 patients were handed over each week. Compliance with mandatory handover of ICU/CCU patients averaged at 59%. Extrapolating our pilot results for the year would result in approximately 1655 handover events per annum in our department. One hundred percent of physicians surveyed felt that documentation of handover was beneficial, and staff satisfaction with handover improved after initiation of the pilot (81 vs 24%, p = 0.000914). While 64% of staff were concerned that typed electronic handover would increase their workload, only 6% of the post pilot survey group felt that it did increase workload significantly.

CONCLUSION

Electronic clinical handover is feasible and practical within the Irish healthcare system. In addition, it was found in our study to be attractive and effective to physicians without increasing their workload.

Abstract OT2-02-03: Pilot study of zirconium-89 bevacizumab positron emission tomography for imaging angiogenesis in patients with inflammatory breast carcinoma receiving preoperative chemotherapy

Background: Inflammatory breast cancer (IBC) continues to have a poor prognosis despite standard tri-modality treatment with chemotherapy, mastectomy and radiation. Current methods of assessing primary tumor response (i.e., clinical exam and breast magnetic resonance imaging [MRI]) are limited for distinguishing residual tumor from responsive disease because of persistent morphologic changes in the breast. Therefore, the inability to accurately assess tumor response during treatment often results in the continuation of ineffective systemic chemotherapy until definitive pathologic evaluation at mastectomy. IBC has a highly angiogenic phenotype which is believed to play a role in this tumor's aggressiveness. The novel radiotracer Zirconium-89 (89Zr)-bevacizumab was developed for imaging tumor angiogenesis with PET. We hypothesize that, as an imaging biomarker of angiogenesis, 89Zr-bevacizumab-PET/CT is a more specific noninvasive functional imaging modality for detecting the presence of tumor angiogenesis compared to current diagnostic methods and will serve as a predictor of response to therapy in patients (pts) with IBC.

Methods: Pts with newly diagnosed HER2neg IBC who will receive preoperative chemotherapy are eligible for this pilot study. 89Zr-bevacizumab-PET/CT, breast MRI and FDG-PET/CT are performed before, after 2 cycles, and at the completion of preoperative therapy. Biopsies of primary IBC tumors are obtained prior to and after 2 cycles of preoperative therapy. At the completion of preoperative therapy, pts proceed to mastectomy or biopsy if ineligible to proceed to mastectomy based on current standards for assessing primary tumor response, i.e., clinical exam, breast MRI and lack of systemic progression. At the time of mastectomy, standard evaluation of the surgical specimen will determine pathologic response of IBC to preoperative chemotherapy. A research sample will be collected if residual cancer is present at the time of mastectomy for histologic evaluation of tumor angiogenesis.

Objectives/Correlatives: The primary objective is to determine feasibility of 89Zr-bevacizumab-PET/CT imaging in pts with IBC. The primary endpoint is assessment of radiolabeling of chelated bevacizumab and number of successfully acquired 89Zr-bevacizumab-PET/CT scans. Correlative studies will be performed on IBC tissue to assess extent of angiogenesis including microvessel density, vessel diameter, vascular pericyte coverage and tumor VEGF levels. Secondary objectives are: 1) To determine if 89Zr-bevacizumab accumulation in primary IBC tumors correlates with the extent of angiogenesis determined by correlative analysis on IBC tissue; 2) To assess the predictive value of 89Zr-bevacizumab-PET/CT after 2 cycles and at the end of preoperative therapy for determining pathologic response at mastectomy as given by residual cancer burden.

Statistics: This is an accrual, not statistical based, feasibility justification. Planned sample size is 10 in order to make a preliminary statement about feasibility and ability for 89Zr-bevacizumab-PET/CT to serve as a surrogate in vivo biomarker of tumor angiogenesis and response to preoperative chemotherapy.

Clinical Trial Information: NCT01894451.

Citation Format: Jacene HA, Overmoyer B, Schlosnagle EJ, Abbott A, Yeh E, Paolino J, Goel S, Culhane A, Bellon JR, Nakhlis F, Hirshfield-Bartek J, Van den Abbeele A. Pilot study of zirconium-89 bevacizumab positron emission tomography for imaging angiogenesis in patients with inflammatory breast carcinoma receiving preoperative chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-02-03.

A progressively wetter climate in southern East Africa over the past 1.3 million years

African climate is generally considered to have evolved towards progressively drier conditions over the past few million years, with increased variability as glacial-interglacial change intensified worldwide. Palaeoclimate records derived mainly from northern Africa exhibit a 100,000-year (eccentricity) cycle overprinted on a pronounced 20,000-year (precession) beat, driven by orbital forcing of summer insolation, global ice volume and long-lived atmospheric greenhouse gases. Here we present a 1.3-million-year-long climate history from the Lake Malawi basin (10°-14° S in eastern Africa), which displays strong 100,000-year (eccentricity) cycles of temperature and rainfall following the Mid-Pleistocene Transition around 900,000 years ago. Interglacial periods were relatively warm and moist, while ice ages were cool and dry. The Malawi record shows limited evidence for precessional variability, which we attribute to the opposing effects of austral summer insolation and the temporal/spatial pattern of sea surface temperature in the Indian Ocean. The temperature history of the Malawi basin, at least for the past 500,000 years, strongly resembles past changes in atmospheric carbon dioxide and terrigenous dust flux in the tropical Pacific Ocean, but not in global ice volume. Climate in this sector of eastern Africa (unlike northern Africa) evolved from a predominantly arid environment with high-frequency variability to generally wetter conditions with more prolonged wet and dry intervals.

Targeted trapping surveys shed new light on the distribution and habitat characteristics of the Carpentarian pseudantechinus (Pseudantechinus mimulus), a threatened dasyurid marsupial

Through a targeted trapping survey we provide important new records and habitat descriptions for the Carpentarian pseudantechinus (Pseudantechinus mimulus) on mainland Australia, including the first records from landscapes dominated by rocks other than sandstone. We hypothesise that continued invasion by an introduced pasture grass may constitute an emerging threatening process to this rare species.

International employment in clinical practice: influencing factors for the dental hygienist

PURPOSE

To assess demographics, job characteristics, geographical regions, resources and commitment, which influence dental hygienists seeking international clinical practice employment opportunities.

METHODS

Questionnaires were mailed to a convenience sample of members of the Dental Hygienists' Association of the City of New York. Statistical analyses were conducted and frequency distributions and relationships between variables were calculated.

RESULTS

Seventy-two percent of respondents reported that they are or may be interested in working overseas. Italy and Spain (67%) were the regions of most interest. Salary (65%) was cited as the most influencing factor in selection, whereas non-compliance with the equivalency to Occupational Safety and Health Administration standards (74%) was the most frequently perceived barrier. Multiple language fluency was statistically significant (0.003) regarding interest in overseas employment.

CONCLUSION

Policy makers, employers and educators need to be aware of these findings should recruitment be a possibility to render urgently needed oral hygiene care in regions where there is a perceived shortage of dental hygienists.

High-oleate peanut mutants result from a MITE insertion into the FAD2 gene

A high-oleate trait in the cultivated peanut ( Arachis hypogaea L.) was reported to rely on the allelic composition of the two homeologous, microsomal oleoyl-PC desaturase genes ( ahFAD2A or ahFAD2B). The enzyme activity of either ahFAD2A or ahFAD2B is sufficient for a normal oleate phenotype, and a significant reduction in the levels of ahFAD2B and a mutation in ahFAD2A were reported to be responsible for the high-oleate phenotype in one chemically induced mutant (M2-225) and one derived from a naturally occurring (8-2122) mutant. Here, we report an insertion of the same miniature inverted-repeat transposable element (MITE) in the ahFAD2B gene in another chemically induced mutant (Mycogen-Flavo) and the previously characterized M2-225 mutant. In both cases, this MITE insertion in ahFAD2B causes a frameshift, resulting in a putatively truncated protein sequence in both mutants. The insertion of this MITE in ahFAD2B, in addition to the point mutation in ahFAD2A, appears to be the cause of the high-oleate phenotype in Mycogen-Flavo and M2-225 mutants. Utilizing sequences of the MITE, we developed a DNA marker strategy to differentiate the two insertion-containing mutants from the normal oleate peanut variety (AT-108) and the naturally occurring, high-oleate mutant 8-2122. Reverse transcript-PCR/differential digestion results reveal the expression of both ahFAD2A and ahFAD2B genes in Mycogen-Flavo mutant. This result is in contrast to the observation that ahFAD2B transcripts are greatly reduced in the M2-225 mutant having the MITE insertion further 3' in ahFAD2B gene.

Development of a clinically feasible logMAR alternative to the Snellen chart: performance of the "compact reduced logMAR" visual acuity chart in amblyopic children

BACKGROUND/AIM

The "compact reduced logMAR" (cRLM) chart is being developed as a logMAR alternative to the Snellen chart. It is closer spaced and has fewer letters per line than conventional logMAR charts. Information regarding the performance of such a chart in amblyopes and children is therefore required. This study aimed to investigate the performance of the cRLM chart in amblyopic children.

METHODS

Timed test and retest measurements using two versions of each chart design were obtained on the amblyopic eye of 43 children. Using the methods of Bland and Altman the agreement, test-retest variability (95% confidence limits for agreement, TRV) and test time of the cRLM and the current clinical standard Snellen chart were compared to the gold standard ETDRS logMAR chart.

RESULTS

No systematic bias between chart designs was found. For line assignment scoring the respective TRVs were 0.20 logMAR, 0.20 logMAR, and 0.30 logMAR. Single letter scoring TRVs were cRLM (95% CL 0.17) logMAR, ETDRS (95% CL 0.14) logMAR, and Snellen (95% CL 0.29) logMAR. Median testing times were ETDRS 60 seconds, cRLM 40 seconds, Snellen 30 seconds.

CONCLUSION

The sensitivity to change of the cRLM equalled or approached that of the gold standard ETDRS and was at least 50% better than that of Snellen. This enhanced sensitivity to change was at the cost of only a 10 second time penalty compared to Snellen. The cRLM chart was approximately half the width of the ETDRS chart. The cRLM chart may represent a clinically acceptable compromise between the desire to obtain logMAR acuities of reasonable and known sensitivity to change, chart size, and testing time.

Analysis of reelin as a candidate gene for autism

Genetic studies indicate that chromosome 7q is likely to contain an autism susceptibility locus (AUTS1). We have followed a positional candidate gene approach to identify relevant gene(s) and report here the analysis of reelin (RELN), a gene located under our peak of linkage. Screening RELN for DNA changes identified novel missense variants absent in a large control group; however, the low frequency of these mutations does not explain the relatively strong linkage results on 7q. Furthermore, analysis of a previously reported triplet repeat polymorphism and intragenic single nucleotide polymorphisms, using the transmission disequilibrium test, provided no evidence for association with autism in IMGSAC and German singleton families. The analysis of RELN suggests that it probably does not play a major role in autism aetiology, although further analysis of several missense mutations is warranted in additional affected individuals.

Excitation by dopamine of rat subthalamic nucleus neurones in vitro-a direct action with unconventional pharmacology

Recent anatomical and physiological studies have pointed to a functional innervation of the subthalamic nucleus by dopamine. This nucleus has a pivotal role in basal ganglia function and voluntary movement control and the possibility that dopamine, and dopaminergic medication used in Parkinson's disease, might directly influence its activity is of considerable interest. We have evaluated electrophysiologically the action and pharmacology of dopamine on single subthalamic neurones in rat brain slices. Dopamine increased firing rate to up to a mean of 60% in 98% of the 261 neurones tested when examined using extracellular single-unit recording. This excitation was unaffected by the GABA antagonist picrotoxin, and the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione, and persisted in a low Ca(2+)/raised Mg(2+) solution, indicative of a direct action, independent of synaptic transmission. Of the 33 cells examined using whole patch-clamp recording, only 13 showed measurable increases in firing rate and/or depolarisations in response to dopamine. Dopamine-responsive cells displayed significantly greater access resistance, suggesting that an unidentified cytoplamic constituent, removed by whole-cell dialysis, was required for the response. Using extracellular recording, the D2-like dopamine receptor agonists quinpirole and bromocryptine, but not the D1-like receptor agonist 1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol, also consistently caused an excitation. This was mimicked by the catecholamine releaser amphetamine in 60% of cells tested. However, the dopamine excitation was not significantly reduced either by the D1-like receptor antagonist 7-chloro8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine or the D2-like receptor antagonists (-)-sulpiride, eticlopride and (+)-butaclamol, and the quinpirole excitation was also unaffected by (-)-sulpiride. In contrast, (-)-sulpiride, eticlopride and (+)-butaclamol all abolished the D2-like receptor-mediated inhibition by dopamine of substantia nigra pars compacta neurones. The alpha-adrenoceptor antagonist phentolamine was a weak antagonist of dopamine excitations, but not of those caused by quinpirole. Dopamine excitations also showed weak sensitivity to the 5-HT(2) antagonist ritanserin, but were unaffected by the alpha(1)-adrenoceptor antagonist prazocin and the beta-adrenoceptor antagonist propranolol. The pharmacology of this dopamine excitation is inconsistent with an action on any known catecholamine receptor. However, the effect of amphetamine indicates that an unidentified monamine--possibly dopamine--can be released within the subthalamic nucleus to cause an excitation. The anomalies of its pharmacological characterisation do not strongly support a physiologically relevant direct action of dopamine in the rat subthalamic nucleus.

A set of simple-sequence repeat (SSR) markers covering the Prunus genome

A set of 109 microsatellite primer pairs recently developed for peach and cherry have been studied in the almond x peach F(2) progeny previously used to construct a saturated Prunus map containing mainly restriction fragment length polymorphism markers. All but one gave amplification products, and 87 (80%) segregated in the progeny and detected 96 loci. The resulting Prunus map contains a total of 342 markers covering a total distance of 522 cM. The approximate position of nine additional simple sequence repeats (SSRs) was established by comparison with other almond and peach maps. SSRs were placed in all the eight linkage groups of this map, and their distribution was relatively even, providing a genome-wide coverage with an average density of 5.4 cM/SSR. Twenty-four single-locus SSRs, highly polymorphic in peach, and each falling within 24 evenly spaced approximately 25-cM regions covering the whole Prunus genome, are proposed as a 'genotyping set' useful as a reference for fingerprinting, pedigree and genetic analysis of this species.

Sorting nexin 3 (SNX3) is disrupted in a patient with a translocation t(6;13)(q21;q12) and microcephaly, microphthalmia, ectrodactyly, prognathism (MMEP) phenotype

A patient with microcephaly, microphthalmia, ectrodactyly, and prognathism (MMEP) and mental retardation was previously reported to carry a de novo reciprocal t(6;13)(q21;q12) translocation. In an attempt to identify the presumed causative gene, we mapped the translocation breakpoints using fluorescence in situ hybridisation (FISH). Two overlapping genomic clones crossed the breakpoint on the der(6) chromosome, locating the breakpoint region between D6S1594 and D6S1250. Southern blot analysis allowed us to determine that the sorting nexin 3 gene (SNX3) was disrupted. Using Inverse PCR, we were able to amplify and sequence the der(6) breakpoint region, which exhibited homology to a BAC clone that contained marker D13S250. This clone allowed us to amplify and sequence the der(13) breakpoint region and to determine that no additional rearrangement was present at either breakpoint, nor was another gene disrupted on chromosome 13. Therefore, the translocation was balanced and SNX3 is probably the candidate gene for MMEP in the patient. However, mutation screening by dHPLC and Southern blot analysis of another sporadic case with MMEP failed to detect any point mutations or deletions in the SNX3 coding sequence. Considering the possibility of positional effect, another candidate gene in the vicinity of the der(6) chromosome breakpoint may be responsible for MMEP in the original patient or, just as likely, the MMEP phenotype in the two patients results from genetic heterogeneity.

A bacterial artificial chromosome (BAC) library for sunflower, and identification of clones containing genes for putative transmembrane receptors

Sunflower (Helianthus annuus L.) is an economically important oil seed crop with an estimated genome size of 3000 Mb. We have constructed a bacterial artificial chromosome (BAC) library for sunflower, which represents an estimated 4- to 5-fold coverage of the genome. Nuclei isolated from young leaves were used as a source of high-molecular-weight DNA and a partial restriction endonuclease digestion protocol was used to cleave the DNA. A random sample of 60 clones indicated an average insert size of 80 kb, implying a 95% probability of recovering any specific sequence of interest. The library was screened with chloroplast DNA probes. Only 0.1% of the clones were identified to be of chloroplast origin, indicating that contamination with organellar DNAs is very low. The utility of the library was evaluated by screening for the presence of genes for putative transmembrane receptors sharing epidermal growth factor (EGF) and integrin-like domains. First, a homologous sunflower EST (HaELP1) was obtained by degenerate RT-PCR cloning, using Arabidopsis thaliana genes (AtELP) as a source of consensus sequences. Three different BACs yielded positive hybridization signals when HaELP1 was used as a probe. BAC subcloning and sequencing demonstrated the presence of two different loci putatively homologous to genes for transmembrane proteins with EGF- and integrin-like domains from sunflower. This work demonstrates the suitability of the library for homology map-based cloning of sunflower genes and physical mapping of the sunflower genome.