The impact of local fugitive particulate matter and emission inventories on air quality and health in dry and arid areas.

The arid and semi-arid regions are facing a huge brunt of fugitive Particulate Matter (fPM) pollution, usually ascribed to the natural dust generated at the regional level (>100 km). In this study, the contribution of locally generated fPM to air pollution and it's environmental risk were assessed at a typical dry-arid area in the Middle East (i.e., State of Qatar, 200 × 200 km2 domain) with the use of different emission and dispersion models. Four modelling scenarios were constructed to reflect standard practices (e.g., regional emission models and the World Health Organization's (WHO) Environmental Burden of Disease (EBD) method) and higher resolution calculations with emission models that were developed in past field campaigns. Emphasis was given to the effect on the WHO methodology beyond the typical emission estimates and ambient concentration levels. Eventually, the use of higher spatial resolution population and concentration data revealed fPM hot spots yielding up to 11.0 times higher short-term excess mortalities (an average increase of 1.8 times) compared to the baseline WHO methodology, where the whole population was exposed to a single average concentration. A difference that could be attributed to the improvement of the emission estimations for barren lands and traffic. For example, the estimated PM10 emission fluxes from barren lands, within the main metropolitan area, using the improved emissions model ranged from 0.05 to 42.0 µg m-2 s-1, which is considerably higher than the emissions predicted using just the literature models (0.03 to 2.0 µg m-2 s-1). Overall, the barren lands emissions accounted for more than 90% of the fPM emissions during the study period. Consequently, this study is one of the first to quantify the significance of locally induced fPM and highlight the need for dedicated field studies and improved emissions estimation tools.

Urinary IgG, serum CX3CL1 and miRNA-152-3p: as predictors of nephropathy in Egyptian type 2 diabetic patients.

The purpose of this study was to assess the role of urinary IgG, serum CX3CL1 and miRNA 152-3p levels as predictors of nephropathy in type 2 Egyptian diabetic patients. Sixty type 2 diabetic patients and twenty healthy controls were enrolled in a cross-sectional study. Then they were grouped into: three groups based upon urine albumin excretion (UAE). The expression of miRNA 152-3p in serum was measured using quantitative polymerase chain reaction (RTq-PCR). Serum CX3CL1 and urinary IgG concentrations were measured by ELISA. RTq-PCR revealed that serum miRNA-152-3p levels in patients were significantly higher than in controls. There was significant differences between group with normoalbuminuria and groups with diabetic nephropathy DN as regard to age, duration of nephropathy, Albumin/Creatinine ratio (A/C ratio), creatinine, urine IgG, CX3CL1 and HbA1c. In diabetic patients, there was a significant positive correlation between miRNA-152-3p levels and disease duration only as well as significant positive correlations between urinary IgG levels and age, disease duration, serum creatinine, A/C ratio, and urea. Positive correlation between serum fractalkine CX3CL1 level and age, duration of disease, urea, creatinine, A/C ratio, HbA1C and IgG in patient with DN. Serum CX3CL1 level, urinary IgG were significantly increased with the progress of nephropathy so these integrated biomarkers could be used as good predictors for early identification of nephropathy. But miRNA- 152-3p has inadequate prognostic indicator for ESRD progression.

Pai syndrome: From the womb until 19 months of age, a neurological development success story.

A prenatal and postnatal follow-up of a child with Pai syndrome, especially till toddler age, allows a better understanding of the evolution of this syndrome. This offers insight on possible outcomes especially in what concerns the neurodevelopment.

Parvovirus B19 Seroprevalence in Women with Bad Obstetric History in Kirkuk.

BACKGROUND: In the Iraqi community, abnormal pregnancy forms a major social and psychological health problem. The underlying etiology of this health phenomenon was varied and included sets of infections and autoimmune diseases. Globally human parvovirus 19 infection is common and the infection attributes to bad obstetric outcomes. The global maternal parvovirus B19 remote infection rate was within a range of 13.2% to 97.9%, while the range of acute infection was between 0.5% to 97.9%. In Arab countries, the IgG seroprevalence was from 53.3% to 74%, while IgM seroprevalence range was 2.2% to 84%. OBJECTIVE: To evaluate the role of ParvovirusB19 as an etiology of bad obstetric outcome in women in Kirkuk, Iraq. MATERIALS AND METHODS: Descriptive Case Control Study. Women included in the study were recruited from Kirkuk General Hospital and their age ranged from 14 to 48 years. A total of 663 women were included in the study, of them 237 were not pregnant, while 215 were pregnant. Additionally, the study included 211 women with inevitable abortion. Control group (306 women) women with a history of normal pregnancy included (Pregnant= 149; non-pregnant= 157). Clinical and laboratory investigations were conducted on all patients and control groups to exclude other causes. Medical and obstetric data and demographic characteristics were gathered through interviews according to a previously designed questionnaire. ELISA kits were used to determine Parvovirus B19 IgM and IgG antibodies. RESULTS: The overall parvovirus seroprevalence was 93% and with no significant difference between women with normal (89.5%) and those with abnormal (93.1%) pregnancy outcomes. In addition, parvovirus IgM overall seroprevalence was at56.3%. Furthermore, current parvovirus infection was higher in women with BOH (52.6%) than that in women with normal pregnancy (49.7%) outcomes. Parvovirus IgM seroprevalence was 52.6% in women with BOH and 49.7% in women with normal pregnancy, however, the difference was not statistically significant. In contrast, the acute infection with parvovirus was significantly (X2=11.8, P=0.001) lower in women with normal pregnancy (49.7%) than in those with inevitable abortion (64.9%). While the IgG seroprevalence difference was not significant between the two groups, infection seroprevalence was more frequent in housewives, uneducated women, large families, non-smokers, in rural areas, non-animal exposure areas, women with repeated abortion, congenital anomalies and anaemia. CONCLUSION: Parvovirus B19 infection may be with bad obstetric outcomes if occurred during pregnancy and OR confirmed a significant association of the infection with parvovirus with smoking, occupation, crowding index, education, animal exposure and the number of repeated abortion.

Obstetric Ultrasound Screening in a Rural Area of Lebanon One Small Step With a Promising Major Impact.

OBJECTIVES: Our aim was to evaluate the conditions and to weigh the potential impact of an obstetrical ultrasound screening intervention on pregnant patients in an underserved area of Lebanon with the presence of refugees. METHODS: We performed a cross-sectional study in a rural region in North Lebanon. Monthly second-trimester obstetrical ultrasound scans were offered to patients. A thorough analysis of the population's characteristics was done, the anomalies discovered were documented and follow up recommendations were offered. RESULTS: 268 screening ultrasounds were performed over a one-year period. The patients' mean age was 27.5 ± 8.5 years with a 35% consanguinity rate. A positive personal history of abnormalities was recognized in 34% of cases, and a positive family history in 21% of them. The average gestational age was of 23.3 ± 1.4 weeks of gestation. We found a rate of 8.6% inaccurate dating, 20% growth abnormalities, and 12% morphological abnormalities requiring follow-up. These latter included defects affecting multiple organ systems among which renal, neurological, and cardiac structures were the most frequently affected (2.5%, 2%, and 1.6% respectively). Overall, 35.8% of the screened cases required a follow-up for 1 or more abnormal findings. CONCLUSIONS: The findings confirmed the necessity to introduce a prenatal ultrasound screening program in rural areas of Lebanon where refugees are settled. The lack of adequate ultrasound screening in these regions presents major threats that can hinder any pregnancy. Our simple intervention tackles the burden of diagnosis of these risks in up to 35.8% of pregnancies and thus can help improve outcomes.

Pyramidal Aberrometry in Wavefront-Guided Myopic LASIK.

PURPOSE: To evaluate measurement repeatability and clinical results for pyramidal aberrometry in routine myopic wavefront-guided laser in situ keratomileusis (LASIK). METHODS: Results from 265 consecutive eyes treated with myopic wavefront-guided LASIK using the Amaris 1050RS Excimer Laser and Peramis pyramidal aberrometer (SCHWIND eye-tech-solutions GmbH) were reviewed. Limits of repeatability were calculated for the aberrometric refraction spherical equivalent and higher order aberrations for the Peramis aberrometer using results from three consecutive scans acquired preoperatively and postoperatively for the first 100 eyes treated. RESULTS: The 95% limits of repeatability for pyramidal aberrometric measurement were: 0.3 diopters (D) for sphere, 0.2 D for cylinder, and 0.1 D (dioptric equivalent) for 3rd and 4th order aberration indices. A total of 95% of eyes were within ±0.50 D of the manifest refraction spherical equivalent target postoperatively. Uncorrected distance visual acuity was 20/20 or better in 96% of 232 eyes with a plano refraction target outcome. A total of 97% of eyes had a refraction cylinder of 0.50 D or less. No eyes lost one or more line of corrected distance visual acuity. CONCLUSIONS: These data demonstrate good measurement repeatability, safety, and efficacy for pyramidal aberrometry in routine myopic LASIK. [J Refract Surg. 2020;36(7):442-448.].

Frequencies of gastrointestinal parasites among students of primary school in Al Kalakla Locality, Khartoum State, Sudan: a cross-sectional study.

Background: Intestinal parasite spread in tropical countries is especially common among primary school students. This study aimed to determine the frequencies of the intestinal parasite in Alkalakla locality, Khartoum state. Methods: This study was conducted in school students in Al-kalakla locality in Khartoum state from period between 20th December 2016 to 5th May 2017. Stool samples were collected from 134 randomly selected students, of whom 67 were males and 67 were females.  All samples were examined using the wet preparation technique, formal ether concentration technique and saturated sugar floatation technique. Results: The frequency of intestinal parasites was 35.5% overall in the students examined; females were more affected than males (38.8% and 32.8%, respectively). The more affected age groups were 12-14 years followed by 9-11 and 6-8 years old (53.8%, 36.3% and 26.4% respectively). The least frequent intestinal parasite was Taenia spp. (1.5%) followed by Giardia lamblia (3.7%), Schistosoma mansoni and Ascaris lumbricoides (5.2% each), Entamoeba coli (7.5%), Hymenolepis nana (10.4%), and Entamoeba histolytica (16.4%). In total, 20.9% were infected with single parasite while 14.9% were infected with more than one parasite. The frequency of parasite by formal ether concentration method was 35.8 %, by wet preparation method was 17.9 % and by the saturated sugar flotation method was 16.4%. Conclusion: Our data showed that intestinal parasites were common in school students; however, females were more affected than males and the 12-14-years age group was the most affected age group.  The formal ether concentration method was the best method for detecting of intestinal parasite.

Different Materials Used as Denture Retainers and Their Colour Stability.

BACKGROUND: Retainers are of great importance for the longevity of the prosthetic removable partial denture during various functions especially the esthetic one. The key of successful clasp selection is to select a direct retainer that will control tipping and torquing forces on the abutment teeth, provide retention against reasonable dislodging forces and are compatible with both tooth and tissue contour together with the aesthetic desire of the patient. AIM: This study aims to compare different clasp material to enhance the choice of the clasp based on the aesthetic point of view. METHODS: The colour evaluation of the tested materials had been evaluated by computer aided technique with digital camera with 3 Mega Pixels of resolution. RESULTS: In the current research, the technique of colour evaluation was carried out to compare different clasp materials to enhance the choice of the clasp based on the aesthetic point of view. Most commonly, Removable Partial Denture (RPD) retainers are fabricated identically from the metal framework's alloy as Cobalt Chromium (CoCr) alloy although it is unaesthetic. This esthetic problem has been overcome by other methods and by utilising different materials, these included covering the retainers with tooth-coloured acrylic resin, as well as the introduction of esthetic materials as; Thermoplastic Acetal, Versacryl, and Thermopress. CONCLUSION: It has been concluded that the non-metallic Acetal resin clasp shows superior physical properties regarding colour stability.

Comparative Study Clarifying the Most Suitable Material to Be Used as Partial Denture Clasps.

BACKGROUND: Removable partial denture's clasp is of particular importance as it affects the denture longevity during the function. The key of successful clasp selection is to select a direct retainer that will control tipping and torquing forces on the abutment teeth, provide retention against reasonable dislodging forces and are compatible with both tooth and tissue contour and the aesthetic desire of the patient. In this consideration, different materials employed for the clasp construction were compared mechanically. AIM: This study aims to compare the most usable esthetic clasps mechanically to clarify the most suitable material to be used as partial denture clasps. METHODS: Evaluation of surface roughness, retention and deformation has been investigated utilising different in-vitro methods. All these techniques provide valuable information regarding the mechanical properties of the materials tested. However, none of the in-vitro techniques can expose the tested materials to conditions similar to that of the oral environment (in-vivo) such as pH value and temperature variations. RESULTS: Most commonly, RPD clasps are fabricated from the same alloy of the metal framework, as cobalt-chromium (CoCr) alloy although it is unaesthetic. Other methods consumed to avoid such esthetic mystery have included coating retainers with tooth-coloured resin or introduction of esthetic materials as Thermoplastic Acetal, Versacryl, and Thermopress. CONCLUSION: It has been concluded that the non-metal Acetal resin retainer reveals superior mechanical properties.

Multiple regression analysis in nomogram development for myopic wavefront laser in situ keratomileusis: Improving astigmatic outcomes.

PURPOSE: To describe and evaluate a new multiple regression-derived nomogram for myopic wavefront laser in situ keratomileusis (LASIK). SETTING: Moorfields Eye Hospital, London, United Kingdom. DESIGN: Prospective comparative case series. METHODS: Multiple regression modeling was used to derive a simplified formula for adjusting attempted spherical correction in myopic LASIK. An adaptation of Thibos' power vector method was then applied to derive adjustments to attempted cylindrical correction in eyes with 1.0 diopter (D) or more of preoperative cylinder. These elements were combined in a new nomogram (nomogram II). RESULTS: The 3-month refractive results for myopic wavefront LASIK (spherical equivalent ≤11.0 D; cylinder ≤4.5 D) were compared between 299 consecutive eyes treated using the earlier nomogram (nomogram I) in 2009 and 2010 and 414 eyes treated using nomogram II in 2011 and 2012. There was no significant difference in treatment accuracy (variance in the postoperative manifest refraction spherical equivalent error) between nomogram I and nomogram II (P = .73, Bartlett test). Fewer patients treated with nomogram II had more than 0.5 D of residual postoperative astigmatism (P = .0001, Fisher exact test). There was no significant coupling between adjustments to the attempted cylinder and the achieved sphere (P = .18, t test). CONCLUSIONS: Discarding marginal influences from a multiple regression-derived nomogram for myopic wavefront LASIK had no clinically significant effect on treatment accuracy. Thibos' power vector method can be used to guide adjustments to the treatment cylinder alongside nomograms designed to optimize postoperative spherical equivalent results in myopic LASIK. mentioned.

Brittle cornea syndrome ZNF469 mutation carrier phenotype and segregation analysis of rare ZNF469 variants in familial keratoconus.

PURPOSE: Brittle cornea syndrome 1 (BCS1) is a rare recessive condition characterized by extreme thinning of the cornea and sclera, caused by mutations in ZNF469. Keratoconus is a relatively common disease characterized by progressive thinning and ectasia of the cornea. The etiology of keratoconus is complex and not yet understood, but rare ZNF469 variants have recently been associated with disease. We investigated the phenotype of BCS1 carriers with known pathogenic ZNF469 mutations, and recruited families in which aggregation of keratoconus was observed to establish if rare variants in ZNF469 segregated with disease. METHODS: Patients and family members were recruited and underwent comprehensive anterior segment examination, including corneal topography. Blood samples were donated and genomic DNA was extracted. The coding sequence and splice sites of ZNF469 were PCR amplified and Sanger sequenced. RESULTS: Four carriers of three BCS1-associated ZNF469 loss-of-function mutations (p.[Glu1392Ter], p.[Gln1930Argfs*6], p.[Gln1930fs*133]) were examined and none had keratoconus. One carrier had partially penetrant features of BCS1, including joint hypermobility. ZNF469 sequencing in 11 keratoconus families identified 9 rare (minor allele frequency [MAF] ≤ 0.025) variants predicted to be potentially damaging. However, in each instance the rare variant(s) identified, including two previously reported as potentially keratoconus-associated, did not segregate with the disease. CONCLUSIONS: The presence of heterozygous loss-of-function alleles in the ZNF469 gene did not cause keratoconus in the individuals examined. None of the rare nonsynonymous ZNF469 variants identified in the familial cohort conferred a high risk of keratoconus; therefore, genetic variants contributing to disease pathogenesis in these 11 families remain to be identified.

Association of CHRDL1 mutations and variants with X-linked megalocornea, Neuhäuser syndrome and central corneal thickness.

We describe novel CHRDL1 mutations in ten families with X-linked megalocornea (MGC1). Our mutation-positive cohort enabled us to establish ultrasonography as a reliable clinical diagnostic tool to distinguish between MGC1 and primary congenital glaucoma (PCG). Megalocornea is also a feature of Neuhäuser or megalocornea-mental retardation (MMR) syndrome, a rare condition of unknown etiology. In a male patient diagnosed with MMR, we performed targeted and whole exome sequencing (WES) and identified a novel missense mutation in CHRDL1 that accounts for his MGC1 phenotype but not his non-ocular features. This finding suggests that MMR syndrome, in some cases, may be di- or multigenic. MGC1 patients have reduced central corneal thickness (CCT); however no X-linked loci have been associated with CCT, possibly because the majority of genome-wide association studies (GWAS) overlook the X-chromosome. We therefore explored whether variants on the X-chromosome are associated with CCT. We found rs149956316, in intron 6 of CHRDL1, to be the most significantly associated single nucleotide polymorphism (SNP) (p = 6.81×10(-6)) on the X-chromosome. However, this association was not replicated in a smaller subset of whole genome sequenced samples. This study highlights the importance of including X-chromosome SNP data in GWAS to identify potential loci associated with quantitative traits or disease risk.

Topography-guided transepithelial photorefractive keratectomy for irregular astigmatism using a 213 nm solid-state laser.

PURPOSE: To explore the use of the Pulsar Z1 solid-state 213 nm photorefractive laser platform in topography-guided transepithelial photorefractive keratectomy (PRK) for irregular astigmatism. SETTING: Moorfields Eye Hospital, London, United Kingdom. DESIGN: Prospective clinical case series. METHODS: Patients with irregular astigmatism after previous refractive surgery or corneal transplantation were treated with topography-guided transepithelial PRK. Preoperatively and 1-year postoperatively, corrected distance visual acuity (CDVA) and secondary outcome measures (including manifest refraction, contrast sensitivity, haze score, index of surface variation, root-mean-square higher-order aberrations, and subjective visual change) were compared between groups. Adjunctive mitomycin-C was not used. RESULTS: Seven patients had previous refractive surgery, and 7 had previous corneal transplantation. All but 2 patients with a marked haze response had subjective gains in vision and improved CDVA. Gains in CDVA for patients with irregular astigmatism after previous refractive surgery (median 2 lines gain; range 0 to 2 lines gained) were higher than for patients with irregular astigmatism after keratoplasty (median 0 lines; range 5 lines lost to 4 lines gained). Trends in secondary outcome measures were similar, with greater variation in post-keratoplasty patients. Haze scores were higher in post-keratoplasty patients. CONCLUSIONS: 213 nm topography-guided transepithelial PRK was easy to perform and well tolerated by patients with irregular astigmatism. Most patients gained CDVA; however, increased haze responses were observed in post-keratoplasty cases.

Ocular complications of bungee jumping.

AIM: In this paper, we will try to highlight the importance of various investigations and their crucial role in identifying whether the defect is structural or functional. CASE HISTORY: A 24-year-old woman presented with ocular complications after bungee jumping. Subsequently, although all ophthalmic signs resolved, she complained of decreased vision in her left eye. CONCLUSION: Initial ophthalmic injury was detected by optical coherence tomography scan showing a neurosensory detachment of the fovea. This was not initially detected on slit-lamp examination or fluorescein angiography. On later examination, although the optical coherence tomography scan showed no structural damage, electrodiagnostic tests showed a functional defect at the fovea.

Keratoconus in 18 pairs of twins.

PURPOSE: To describe the concordance of keratoconus in 18 sets of twins. METHODS: Thirteen monozygotic (MZ) and five dizygotic (DZ) pairs of twins were identified during an investigation of familial keratoconus. We used 16 forensic microsatellite markers to confirm the zygosity of same sex twins. Patients and available relatives were examined for signs of keratoconus using corneal topography. For each pair of twins, the severity of keratoconus in each eye was graded according to the steepest keratometry value and the average difference in score between the MZ and DZ twins compared. RESULTS: All of the MZ twins and four of the five DZ twins were concordant for keratoconus but with differences in age of onset and severity of disease. The subjective age of onset of keratoconus tended to be earlier in the MZ twins (16.4 years, SD 4.66) than in the DZ twins (20.3 years, SD 7.55) (p=0.086). Additional relatives with keratoconus were identified in two (16%) of the families with MZ twins and in three (60%) of the families of DZ twins. The mean difference in severity scores was 1.4 (SD 1.73) for the MZ twins and 3.0 (SD 1.00) for the DZ twins (p=0.035). CONCLUSION: This data provide evidence that the severity of keratoconus is more concordant in MZ than in DZ twins. The results support the currently accepted hypothesis of an important genetic contribution towards the pathogenesis of keratoconus, but suggest that there is also an environmental effect on the expression of disease.

X-linked megalocornea caused by mutations in CHRDL1 identifies an essential role for ventroptin in anterior segment development.

X-linked megalocornea (MGC1) is an ocular anterior segment disorder characterized by an increased cornea diameter and deep anterior chamber evident at birth and later onset of mosaic corneal degeneration (shagreen), arcus juvenilis, and presenile cataracts. We identified copy-number variation, frameshift, missense, splice-site and nonsense mutations in the Chordin-like 1 gene (CHRDL1) on Xq23 as the cause of the condition in seven MGC1 families. CHRDL1 encodes ventroptin, a bone morphogenic protein antagonist with a proposed role in specification of topographic retinotectal projections. Electrophysiological evaluation revealed mild generalized cone system dysfunction and, in one patient, an interhemispheric asymmetry in visual evoked potentials. We show that CHRDL1 is expressed in the developing human cornea and anterior segment in addition to the retina. We explored the impact of loss of ventroptin function on brain function and morphology in vivo. CHRDL1 is differentially expressed in the human fetal brain, and there is high expression in cerebellum and neocortex. We show that MGC1 patients have a superior cognitive ability despite a striking focal loss of myelination of white matter. Our findings reveal an unexpected requirement for ventroptin during anterior segment development and the consequences of a lack of function in the retina and brain.

Candida albicans keratitis in an immunocompromised patient.

PURPOSE: When investigating a case of unexplained corneal ulceration, we need to think of fungal infection and any predisposing factors. METHODS: A case study of a corneal ulceration in a patient who was HIV positive with a devastating visual outcome. RESULTS: Therapeutic corneal graft was necessary due to corneal perforation. Immunocompromised state of patient was retrospectively diagnosed. CONCLUSIONS: Candida albicans keratitis is an opportunistic infection of a compromised cornea, and sometimes unknowingly compromised host, which can be initially misdiagnosed. Despite intensive antifungal therapy, occasionally patients require corneal grafting to improve vision, and before it is possible to establish an accurate diagnosis.

JACKDAW controls epidermal patterning in the Arabidopsis root meristem through a non-cell-autonomous mechanism.

In Arabidopsis, specification of the hair and non-hair epidermal cell types is position dependent, in that hair cells arise over clefts in the underlying cortical cell layer. Epidermal patterning is determined by a network of transcriptional regulators that respond to an as yet unknown cue from underlying tissues. Previously, we showed that JACKDAW (JKD), a zinc finger protein, localizes in the quiescent centre and the ground tissue, and regulates tissue boundaries and asymmetric cell division by delimiting SHORT-ROOT movement. Here, we provide evidence that JKD controls position-dependent signals that regulate epidermal-cell-type patterning. JKD is required for appropriately patterned expression of the epidermal cell fate regulators GLABRA2, CAPRICE and WEREWOLF. Genetic interaction studies indicate that JKD operates upstream of the epidermal patterning network in a SCRAMBLED (SCM)-dependent fashion after embryogenesis, but acts independent of SCM in embryogenesis. Tissue-specific induction experiments indicate non-cell-autonomous action of JKD from the underlying cortex cell layer to specify epidermal cell fate. Our findings are consistent with a model where JKD induces a signal in every cortex cell that is more abundant in the hair cell position owing to the larger surface contact of cells located over a cleft.

Arabidopsis JACKDAW and MAGPIE zinc finger proteins delimit asymmetric cell division and stabilize tissue boundaries by restricting SHORT-ROOT action.

In the Arabidopsis root, the SHORT-ROOT transcription factor moves outward to the ground tissue from its site of transcription in the stele and is required for the specification of the endodermis and the stem cell organizing quiescent center cells. In addition, SHORT-ROOT and the downstream transcription factor SCARECROW control an oriented cell division in ground tissue stem cell daughters. Here, we show that the JACKDAW and MAGPIE genes, which encode members of a plant-specific family of zinc finger proteins, act in a SHR-dependent feed-forward loop to regulate the range of action of SHORT-ROOT and SCARECROW. JACKDAW expression is initiated independent of SHORT-ROOT and regulates the SCARECROW expression domain outside the stele, while MAGPIE expression depends on SHORT-ROOT and SCARECROW. We provide evidence that JACKDAW and MAGPIE regulate tissue boundaries and asymmetric cell division and can control SHORT-ROOT and SCARECROW activity in a transcriptional and protein interaction network.

Whole-genome analysis of the SHORT-ROOT developmental pathway in Arabidopsis.

Stem cell function during organogenesis is a key issue in developmental biology. The transcription factor SHORT-ROOT (SHR) is a critical component in a developmental pathway regulating both the specification of the root stem cell niche and the differentiation potential of a subset of stem cells in the Arabidopsis root. To obtain a comprehensive view of the SHR pathway, we used a statistical method called meta-analysis to combine the results of several microarray experiments measuring the changes in global expression profiles after modulating SHR activity. Meta-analysis was first used to identify the direct targets of SHR by combining results from an inducible form of SHR driven by its endogenous promoter, ectopic expression, followed by cell sorting and comparisons of mutant to wild-type roots. Eight putative direct targets of SHR were identified, all with expression patterns encompassing subsets of the native SHR expression domain. Further evidence for direct regulation by SHR came from binding of SHR in vivo to the promoter regions of four of the eight putative targets. A new role for SHR in the vascular cylinder was predicted from the expression pattern of several direct targets and confirmed with independent markers. The meta-analysis approach was then used to perform a global survey of the SHR indirect targets. Our analysis suggests that the SHR pathway regulates root development not only through a large transcription regulatory network but also through hormonal pathways and signaling pathways using receptor-like kinases. Taken together, our results not only identify the first nodes in the SHR pathway and a new function for SHR in the development of the vascular tissue but also reveal the global architecture of this developmental pathway.