Anthropogenic impacts on threatened species erode functional diversity in chelonians and crocodilians.

The Anthropocene is tightly associated with a drastic loss of species worldwide and the disappearance of their key ecosystem functions. The orders Testudines (turtles and tortoises) and Crocodilia (crocodiles, alligators, and gharials) contain numerous threatened, long-lived species for which the functional diversity and potential erosion by anthropogenic impacts remains unknown. Here, we examine 259 (69%) of the existing 375 species of Testudines and Crocodilia, quantifying their life history strategies (i.e., trade-offs in survival, development, and reproduction) from open-access data on demography, ancestry, and threats. We find that the loss of functional diversity in simulated extinction scenarios of threatened species is greater than expected by chance. Moreover, the effects of unsustainable local consumption, diseases, and pollution are associated with life history strategies. In contrast, climate change, habitat disturbance, and global trade affect species independent of their life history strategy. Importantly, the loss of functional diversity for threatened species by habitat degradation is twice that for all other threats. Our findings highlight the importance of conservation programmes focused on preserving the functional diversity of life history strategies jointly with the phylogenetic representativity of these highly threatened groups.

Higher sociability leads to lower reproductive success in female kangaroos.

In social mammals, social integration is generally assumed to improve females' reproductive success. Most species demonstrating this relationship exhibit complex forms of social bonds and interactions. However, female eastern grey kangaroos (Macropus giganteus) exhibit differentiated social relationships, yet do not appear to cooperate directly. It is unclear what the fitness consequences of such sociability could be in species that do not exhibit obvious forms of cooperation. Using 4 years of life history, spatial and social data from a wild population of approximately 200 individually recognizable female eastern grey kangaroos, we tested whether higher levels of sociability are associated with greater reproductive success. Contrary to expectations, we found that the size of a female's social network, her numbers of preferential associations with other females and her group sizes all negatively influenced her reproductive success. These factors influenced the survival of dependent young that had left the pouch rather than those that were still in the pouch. We also show that primiparous females (first-time breeders) were less likely to have surviving young. Our findings suggest that social bonds are not always beneficial for reproductive success in group-living species, and that female kangaroos may experience trade-offs between successfully rearing young and maintaining affiliative relationships.

Changes in local free-living parasite populations in response to cleaner manipulation over 12 years.

Predation on parasites is an important ecological process, but few experimental studies have examined the long-term impacts on the prey. Cleaner fish prey upon large numbers and selectively feed on the larger individuals of the ectoparasitic stage of gnathiid isopods. Removal of cleaner fish Labroides dimidiatus for 1.5-12.5 years negatively affects coral reef fishes, but the mechanism is unclear. A reduction in local parasite populations or the size of individual parasites would benefit all susceptible fishes. We tested whether cleaner presence reduces local gnathiid populations using 18 patch-reefs distributed between two sites (both at Lizard Island, Great Barrier Reef) which were maintained cleaner-free or undisturbed for 12 years. Using emergence traps (1 m2), free-living gnathiid stages were sampled before and after cleaner fish were removed during the day and night, up to 11 times over the course of the experiment. There were effects of the removal in the predicted direction, driven largely by the response at one site over the other involving 200% more gnathiids, but manifested only in the daytime sampling after 4 months. There was also a main effect (36%) for the shared sample dates at both sites after 12 years. Gnathiid size occasionally differed with cleaner presence, but in no consistent way over time. Contrary to our predictions, changes in free-living gnathiid population numbers and their size structure rarely reflected the changes in fish populations and individuals observed on cleaner-free reefs. Therefore, evidence that this predator alone regulates gnathiids remains limited, suggesting other contributing processes are involved.

Combining high-energy X-ray diffraction with Surface Optical Reflectance and Planar Laser Induced Fluorescence for operando catalyst surface characterization.

We have combined three techniques, High Energy Surface X-Ray Diffraction (HESXRD), Surface Optical Reflectance, and Planar Laser Induced Fluorescence in an operando study of CO oxidation over a Pd(100) catalyst. We show that these techniques provide useful new insights such as the ability to verify that the finite region being probed by techniques such as HESXRD is representative of the sample surface as a whole. The combination is also suitable to determine when changes in gas composition or surface structure and/or morphology occur and to subsequently correlate them with high temporal resolution. In the study, we confirm previous results which show that the Pd(100) surface reaches high activity before an oxide can be detected. Furthermore, we show that the single crystal catalyst surface does not behave homogeneously, which we attribute to the surface being exposed to inhomogeneous gas conditions in mass transfer limited scenarios.

Conspicuous visual signals do not coevolve with increased body size in marine sea slugs.

Many taxa use conspicuous colouration to attract mates, signal chemical defences (aposematism) or for thermoregulation. Conspicuousness is a key feature of aposematic signals, and experimental evidence suggests that predators avoid conspicuous prey more readily when they exhibit larger body size and/or pattern elements. Aposematic prey species may therefore evolve a larger body size due to predatory selection pressures, or alternatively, larger prey species may be more likely to evolve aposematic colouration. Therefore, a positive correlation between conspicuousness and body size should exist. Here, we investigated whether there was a phylogenetic correlation between the conspicuousness of animal patterns and body size using an intriguing, understudied model system to examine questions on the evolution of animal signals, namely nudibranchs (opisthobranch molluscs). We also used new ways to compare animal patterns quantitatively with their background habitat in terms of intensity variance and spatial frequency power spectra. In studies of aposematism, conspicuousness is usually quantified using the spectral contrast of animal colour patches against its background; however, other components of visual signals, such as pattern, luminance and spectral sensitivities of potential observers, are largely ignored. Contrary to our prediction, we found that the conspicuousness of body patterns in over 70 nudibranch species decreased as body size increased, indicating that crypsis was not limited to a smaller body size. Therefore, alternative selective pressures on body size and development of colour patterns, other than those inflicted by visual hunting predators, may act more strongly on the evolution of aposematism in nudibranch molluscs.

A high pressure x-ray photoelectron spectroscopy study of CO oxidation over Rh(100).

We have studied the oxidation of CO over Rh(100) using high pressure x-ray photoelectron spectroscopy under CO and O2 pressures ranging from 0.01 to 1 mbar. The results show a very low or no conversion for the CO covered surface found at low temperatures, while the activity rises slightly when the temperature is high enough for some CO to desorb, exposing surface sites for dissociative O2 adsorption. As the temperature is increased further, more CO desorbs and oxygen replaces CO as the dominating species at the surface. At the same time we find a sudden increase in the reactivity, such that all CO that reaches the surface is instantly transformed into CO2. We find that the O coverage in the active state is highly dependent on the total pressure and, although we do not detect any presence of a surface oxide as in previous surface x-ray diffraction studies, the highest O coverage indicates that the surface is close to being oxidized.

In situ x-ray photoelectron spectroscopy of model catalysts: at the edge of the gap.

We present high-pressure x-ray photoelectron spectroscopy (HP-XPS) and first-principles kinetic Monte Carlo study addressing the nature of the active surface in CO oxidation over Pd(100). Simultaneously measuring the chemical composition at the surface and in the near-surface gas phase, we reveal both O-covered pristine Pd(100) and a surface oxide as stable, highly active phases in the near-ambient regime accessible to HP-XPS. Surprisingly, no adsorbed CO can be detected during high CO(2) production rates, which can be explained by a combination of a remarkably short residence time of the CO molecule on the surface and mass-transfer limitations in the present setup.

An in situ set up for the detection of CO2 from catalytic CO oxidation by using planar laser-induced fluorescence.

We report the first experiment carried out on an in situ setup, which allows for detection of CO(2) from catalytic CO oxidation close to a model catalyst under realistic reaction conditions by the means of planar laser-induced fluorescence (PLIF) in the mid-infrared spectral range. The onset of the catalytic reaction as a function of temperature was followed by PLIF in a steady state flow reactor. After taking into account the self-absorption of CO(2), a good agreement between the detected CO(2) fluorescence signal and the CO(2) mass spectrometry signal was shown. The observed difference to previously measured onset temperatures for the catalytic ignition is discussed and the potential impact of IR-PLIF as a detection technique in catalysis is outlined.

Sick leave reductions from a comprehensive manual therapy programme for low back pain: the Gotland Low Back Pain Study.

OBJECTIVE: To evaluate if a comprehensive manual therapy programme reduces sick leave due low back pain and facilitates return to work more than the conventional optimized activating care. DESIGN: A randomized controlled trial over a 10-week period with a two-year follow-up. SETTING: Primary health care and Visby Hospital, Municipality of Gotland, Sweden. SUBJECTS: One hundred and sixty patients (70 women, 90 men, ages 20-55 years) with acute or subacute low back pain with or without pain radiation into the legs. INTERVENTIONS: Standardized optimized activating care (n = 71) versus a comprehensive pragmatic manual therapy programme including specific corticosteroid injections (n = 89). MAIN MEASURES: Sick leave measured as net sick leave volume, point prevalence and return to work. RESULTS: After 10 weeks, significantly more manual therapy patients than reference patients had returned to work (hazards ratio 1.62, 95% confidence interval (CI) 1.006-2.60, P<0.05), and among those on sick leave at baseline, significantly fewer were still on sick leave (8/58 versus 13/40, ratio 0.35, 95% CI 0.13-0.97, P<0.05). For all other measures there were inconclusive differences in favour of the manual therapy group. No significant differences remained after two years. CONCLUSIONS: The manual therapy programme used in this study decreased sick leave and increased return to work more than the standardized optimized activating care only up to 10 weeks but not up to two years.

Traction for low-back pain with or without sciatica.

BACKGROUND: Traction is used to treat low-back pain (LBP), often with other treatments. OBJECTIVES: To determine traction's effectiveness, compared to reference treatments, placebo, sham traction or no treatment for LBP. SEARCH STRATEGY: We searched CENTRAL (The Cochrane Library 2006, issue 4), MEDLINE, EMBASE, and CINAHL to October 2006, references in relevant reviews and personal files. SELECTION CRITERIA: Randomized controlled trials (RCTs) involving traction to treat acute (less than four weeks duration), sub-acute (four to 12 weeks) or chronic (more than 12 weeks) non-specific LBP with or without sciatica. DATA COLLECTION AND ANALYSIS: Study selection, methodological quality assessment and data extraction were done independently by two authors. As there were insufficient data for statistical pooling, we performed a qualitative analysis. MAIN RESULTS: We included 25 RCTs (2206 patients; 1045 receiving traction). Five trials were considered high quality. For patients with mixed symptom patterns (acute, sub-acute and chronic LBP with and without sciatica) there is: strong evidence of no statistically significant difference in outcomes between traction as a single treatment and placebo, sham or no treatment; moderate evidence that traction as a single treatment is no more effective than other treatments; limited evidence of no significant difference in outcomes between a standard physical therapy program with or without continuous traction. For LBP patients with sciatica (with acute, sub-acute or chronic pain), there is conflicting evidence in several comparisons: autotraction compared to placebo, sham or no treatment; other forms of traction compared to other treatments; different forms of traction. In other comparisons, there were no statistically significant differences; the evidence is moderate for continuous or intermittent traction compared to placebo, sham or no treatment, and limited for light versus normal force traction. IMPLICATIONS FOR PRACTICE: The results of the available studies involving mixed groups of acute, sub-acute and chronic patients with LBP with and without sciatica were quite consistent, indicating that continuous or intermittent traction as a single treatment for LBP is not likely effective for this group. Traction for patients with sciatica cannot be judged effective at present either, due to inconsistent results and methodological problems in most studies. We conclude that traction as a single treatment for LBP is probably not effective. IMPLICATIONS FOR RESEARCH: Any future research on traction for patients with LBP should distinguish between symptom pattern and duration, and should be carried out according to the highest methodological standards.

Traction for low-back pain with or without sciatica.

BACKGROUND: Various types of traction are used in the treatment of low-back pain (LBP), often in conjunction with other treatments. OBJECTIVES: To determine the effectiveness of traction in the management of LBP. SEARCH STRATEGY: We searched The Cochrane Library 2004, Issue 4, MEDLINE, EMBASE, and CINAHL to November 2004, references in relevant reviews, and our personal files. SELECTION CRITERIA: Randomized controlled trials (RCTs) examining any type of traction for the treatment of acute (less than four weeks duration), sub-acute (four to 12 weeks) or chronic (more than 12 weeks) non-specific LBP with or without sciatica. DATA COLLECTION AND ANALYSIS: Study selection, methodological quality assessment and data extraction were done independently by sets of two reviewers. As available studies did not provide sufficient data for statistical pooling, a qualitative analysis was performed. MAIN RESULTS: Twenty-four RCTs, involving 2177 patients (1016 receiving traction) were included in the review. Five trials were considered high quality. There is strong evidence that there is no significant difference in short or long-term outcomes between either continuous or intermittent traction and placebo, sham, or other treatments for patients with a mixed duration of LBP, with or without sciatica. There is moderate evidence that: autotraction is more effective other forms of traction are no more effective than placebo, sham or no treatment for patients with a mixed duration of LBP with sciatica. There is limited evidence that: there is no significant difference in outcomes between a standard physical therapy program with continuous traction and the same program without traction, for patients with a mixed duration of LBP, with or without sciatica autotraction on its own is more effective than a physical therapy program that includes Tru-Trac traction for patients with a mixed duration of LBP with sciatica. There is conflicting evidence regarding the short-term effectiveness of either continuous or intermittent traction compared to placebo, sham or other treatments, in the management of patients who have either chronic LBP or a mixed duration of LBP with sciatica. AUTHORS' CONCLUSIONS: The evidence suggests that traction is probably not effective. Neither continuous nor intermittent traction by itself was more effective in improving pain, disability or work absence than placebo, sham or other treatments for patients with a mixed duration of LBP, with or without sciatica. Although trials studying patients with sciatica had methodological limitations and inconsistent results, there was moderate evidence that autotraction was more effective than mechanical traction for global improvement in this population.

Estimation of fetal urinary bladder volume using the sum-of-cylinders method vs. the ellipsoid formula.

OBJECTIVES: A changing hourly fetal urine production rate (HFUPR) has been demonstrated when fetuses are subjected to hypoxia, which is of clinical interest. Conventionally, calculations of the HFUPR have been based on repeated two-dimensional ultrasound bladder images during the filling phase and the formula for ellipsoids. However, the bladder shape changes from the ellipsoidal to super-ellipsoidal during filling and the volume could be underestimated. In this study the sum-of-cylinders method was used, a method which does not depend on the longitudinal bladder shape being an ellipse. METHODS: The volumes from 102 urinary bladder images from 34 fetuses (three per fetus) were assessed using the sum-of-cylinders method. These results were compared with the corresponding findings when using the ellipsoid formula on the identical material of bladder images in a previous study. RESULTS: When using the sum-of-cylinders method vs. the ellipsoid formula, the mean volume difference was +1.6 mL. Applying the sum-of-cylinders method for bladder volumes of 5-40 mL resulted in standard deviations of 8.8-3.5% vs. 12.9-5.5% when using the ellipsoid formula. No deviation was found when using the sum-of-cylinders method vs. a known volume formula for cylinders, which simulated super-ellipsoids on the computer screen. CONCLUSIONS: Volume calculation by the sum-of-cylinders method is independent of the longitudinal bladder shape when it comes to producing accurate estimations. This method demonstrated a systematically larger volume compared with the ellipsoid formula. The sum-of-cylinders method is therefore preferable for volume estimations of the fetal urinary bladder.

Accuracy in estimating fetal urinary bladder volume using a modified ultrasound technique.

OBJECTIVE: Fetal urine production at different gestational ages has been evaluated using ultrasound in several previous studies. In a recent study, we investigated the accuracy when estimating the bladder volume using the conventional ultrasound technique and found a total variability of 17.3-10.9% for bladder volumes of 5-40 mL. The variability is mainly caused by: (i) inappropriate image selection (the 'freezing error') and (ii) limitations when measuring on the frozen image (the 'frozen error'). The aim of this study was to reduce the total error by reducing the 'freezing' and the 'frozen error'. To this end, we used a modified manual ultrasound technique (adding a 'rocking' motion to the conventional method) and digitized the selected image. METHODS: Two patients for each gestational week from 24 to 40 weeks were selected. The fetal urinary bladder was examined with ultrasound three times within 1 min and documented on videotape. The volume, as assessed by the longitudinal section of the recorded bladder images, stored in digitized form, was evaluated on three occasions with > 24 h in between. The mean and variability (standard deviation, SD) were estimated. RESULTS: For fetal bladder volumes between 5 and 40 mL, the 'freezing error' (SD), the 'frozen error' and the 'total error' were 11.7-5.1%, 8.0-3.0% and 14.2-5.9%, respectively. Comparing the present with a previous study, when selecting images and assessing bladder volumes repeatedly within 1 min, SD was 12.9-5.5% vs. 17.3-10.9%. CONCLUSIONS: Using a modified ultrasound technique, the variability in fetal bladder volume estimation can be reduced.

Convergent maternal care strategies in ungulates and macropods.

Mammals show extensive interspecific variation in the form of maternal care. Among ungulates, there is a dichotomy between species in which offspring follow the mother ("following" strategy) versus species in which offspring remain concealed ("hiding" strategy). Here we reveal that the same dichotomy exists among macropods (kangaroos, wallabies and allies). We test three traditional adaptive explanations and one new life history hypothesis, and find very similar patterns among both ungulates and macropods. The three traditional explanations that we tested were that a "following" strategy is associated with (1) open habitat, (2) large mothers, and (3) gregariousness. Our new life-history hypothesis is that a "following strategy" is associated with delayed weaning, and thus with the "slow" end of the slow-fast mammalian life-history continuum, because offspring devote resources to locomotion rather than rapid growth. Our comparative test strongly supports the habitat structure hypothesis and provides some support for this new delayed weaning hypothesis for both ungulates and macropods. We propose that sedentary young in closed habitats benefit energetically by having milk brought to them. In open habitats, predation pressure will select against hiding. Followers will suffer slower growth to independence. Taken together, therefore, our results provide the first quantitative evidence that macropods and ungulates are convergent with respect to interspecific variation in maternal care strategy. In both clades, differences between species in the form of parental care are due to a similar interaction between habitat, social behavior, and life history.

Presence of cutaneous interferon-alpha producing cells in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) patients have increased levels of interferon-alfa (IFN-alpha) in the circulation but a reduced number of functionally intact natural IFN-alpha producing cells (IPC) in peripheral blood. In search for tissue localisation of activated IPC, we investigated skin biopsies from SLE patients for the occurrence of such cells. Eleven SLE patients with inflammatory skin lesions and six healthy controls were biopsied. An immunohistochemical technique (IH) and in situ hybridisation (ISH) were used to detect intracellular IFN-alpha protein and IFN-alpha mRNA, respectively. In all 11 biopsies from SLE lesions, a high number of IPC were detected by IH. In the nonlesional SLE biopsies we could also demonstrate IPC in 10/11 patients. In 6/11 SLE patients, IFN-alpha mRNA containing cells could be detected in the specimens. A low number of IPC were detected in 1/6 healthy controls by IH, but no ISH positive cells were seen. Our results demonstrate that SLE patients have active IPC in both dermal lesions and in noninflammatory skin. A recruitment of IPC from blood to peripheral tissues may explain the low number of circulating natural IPC in SLE patients. Because the type I IFN system is involved in the SLE disease process, these results are of interest for the understanding of the pathogenesis in SLE.

Natural selection and quantitative genetics of life-history traits in Western women: a twin study.

Whether contemporary human populations are still evolving as a result of natural selection has been hotly debated. For natural selection to cause evolutionary change in a trait, variation in the trait must be correlated with fitness and be genetically heritable and there must be no genetic constraints to evolution. These conditions have rarely been tested in human populations. In this study, data from a large twin cohort were used to assess whether selection will cause a change among women in a contemporary Western population for three life-history traits: age at menarche, age at first reproduction, and age at menopause. We control for temporal variation in fecundity (the "baby boom" phenomenon) and differences between women in educational background and religious affiliation. University-educated women have 35% lower fitness than those with less than seven years education, and Roman Catholic women have about 20% higher fitness than those of other religions. Although these differences were significant, education and religion only accounted for 2% and 1% of variance in fitness, respectively. Using structural equation modeling, we reveal significant genetic influences for all three life-history traits, with heritability estimates of 0.50, 0.23, and 0.45, respectively. However, strong genetic covariation with reproductive fitness could only be demonstrated for age at first reproduction, with much weaker covariation for age at menopause and no significant covariation for age at menarche. Selection may, therefore, lead to the evolution of earlier age at first reproduction in this population. We also estimate substantial heritable variation in fitness itself, with approximately 39% of the variance attributable to additive genetic effects, the remainder consisting of unique environmental effects and small effects from education and religion. We discuss mechanisms that could be maintaining such a high heritability for fitness. Most likely is that selection is now acting on different traits from which it did in pre-industrial human populations.

Fetal urine production and accuracy when estimating fetal urinary bladder volume.

OBJECTIVES: The volume of the fetal urinary bladder can be estimated by measuring bladder diameters on an ultrasound image. The calculated urine production rate might reflect the fetal status in compromised pregnancies. The aim of this study was to assess the fetal urine production rate and the accuracy of measurements of diameters and volumes of the bladder. DESIGN: Urine production rate and the variability in volume measurement error were assessed by ultrasound examinations of fetal bladder images documented on videotapes. In material comprising 101 longitudinal and 90 transverse bladder images, the variability (SD) in distance measurement error was estimated for the bladder diameters. Using this SD, the variability in volume measurement error in the selected bladder image was also calculated. RESULTS: The urine production rate for fetuses of 20, 25, 30, 35 and 40 weeks is 4.2, 12.1, 22.7, 36.1 and 52.2 mL/h, respectively. The SD for volume measurement error when selecting bladder images with a volume of 5, 10, 20, 30 and 40 mL is 17.3%, 13.6%, 11.8%, 11.2% and 10.9% of the actual volume, respectively. The corresponding SD when measuring the volume of selected bladder images accounted for 3.7-2.0%. CONCLUSIONS: The urine production rate presented here is in parity with recent previous reports. We distinguish between different kinds of measurement error. The variability was mostly related to the selection of appropriate bladder image, whereas measurement of the selected bladder image accounted for only a minor part of the resulting variability.

Anti-SSA/Ro antibody determination by enzyme-linked immunosorbent assay as a supplement to standard immunofluorescence in antinuclear antibody screening.

The aim of this study was to investigate the frequency and possible clinical relevance of SSA/Ro antibodies, as determined by enzyme-linked immunosorbent assay (ELISA), in patient sera not exhibiting a concomitant positive reaction by the standard immunofluorescence (IF) test using HEP-2 cells as substrate. SSA/Ro reactivity, as shown by ELISA, was found in 285 (7%) of 4025 serum samples consecutively remitted for antinuclear antibody (ANA) screening. Seventy-five of these serum samples (26%), derived from 64 patients, were negative by the IF-ANA screening test. Serum samples from all 64 patients exhibiting SSA/Ro reactivity by ELISA without concomitant positivity by IF-ANA were further investigated by IF using transfected HEP-2 cells hyperexpressing the 60,000 MW SSA/Ro antigen (HEP-2000(R)) and by immunodiffusion (ID) and Western blot. In 55 of these 64 patients, SSA/Ro reactivity could be verified by one or more of the other techniques investigated. Twelve of these patients fulfilled four or more American College of Rheumatology (ACR) criteria for systemic lupus erythematosus (SLE) and another five patients exhibited a histologically confirmed cutaneous lupus erythematosus (LE). In four of the 12 IF-ANA-negative patients with a diagnosis of SLE, the SSA/Ro reactivity was only detectable by ELISA and Western blot. In conclusion, the use of a sensitive ELISA assay could provide a clinically important supplement to the routine ANA screening by IF, which does not detect certain anti-SSA/Ro-containing sera among patients with relevant autoimmune diagnoses. Detection of anti-SSA/Ro antibodies, however, does not alone signify cutaneous LE or SLE but adds weight to these diagnoses that should rely heavily on other clinical information.

Ro 52kD autoantibodies are detected in a subset of ANA-negative sera.

To define Ro 52kD, Ro 60kD, and La specificities of autoantibodies within ANA-negative sera, samples from 64 ANA-negative but SSA positive patients undergoing investigation due to suspected CTD were analysed, using recombinant antigens and synthetic peptides by immunoblotting and ELISA. The sera were selected from 4025 sera submitted for routine ANA analysis. Antibodies to Ro or La were detected in 42/64 sera (65%). Anti-Ro 52kD antibodies occurred most frequently and were present in 42/64 sera (65%). This was the only specificity of autoantibody detected in 18 sera. No patient had only anti-La or anti-Ro 60 antibodies. In total 18.64 patients (28%) had Ro 60 antibodies and 14/64 had anti-La antibodies (21%). Eight patients had antibodies reacting with all three antigens. We used the same set of sera to test the antigenicity of different regions of Ro 52kD represented by deletion clones and peptides derived from the Ro 52kD sequence. Out of 30 sera reacting with a recombinant deletion clone encompassing as residues 136-227, 12 sera reacted with a peptide corresponding to a 200-239. Some sera gave a low positive OD value with a peptide of a 176-196. Based on the results of this study in which we demonstrate Ro 52kD autoantibodies in 65% of selected ANA negative sera and define an autocephitope within the Ro 52kD protein composed of the leucine zipper domain, we suggest that testing for Ro 52kD antibodies could be included in an extended investigation of ANA negative patients with suspected connective tissue disease.