Levels of the endosymbiont Rickettsia in the whitefly Bemisia tabaci are influenced by the expression of vitellogenin.

Bacterial endosymbionts play essential roles in the biology of their arthropod hosts by interacting with internal factors in the host. The whitefly Bemisia tabaci is a worldwide agricultural pest and a supervector for more than 100 plant viruses. Like many other arthropods, Be. tabaci harbours a primary endosymbiont, Porteira aleyrodidarum, and an array of secondary endosymbionts that coexist with Portiera inside bacteriocyte cells. Unlike all of the other secondary symbionts that infect Be. tabaci, Rickettsia has been shown to be an exception by infecting insect organs and not colocalizing with Portiera, and has been shown to significantly impact the insect biology and its interactions with the environment. Little is known about the molecular interactions that underlie insect-symbiont interactions in general, and particularly Be. tabaci-Rickettsia interactions. Here we performed transcriptomic analysis and identified vitellogenin as an important protein that influences the levels of Rickettsia in Be. tabaci. Vitellogenin expression levels were lower in whole insects, but higher in midguts of Rickettsia-infected insects. Immunocapture-PCR assay showed interaction between vitellogenin and Rickettsia, whereas silencing of vitellogenin resulted in nearly complete disappearance of Rickettsia from midguts. Altogether, these results suggest that vitellogenin plays an important role in influencing the levels of Rickettsia in Be. tabaci.

Downregulation of dystrophin expression in pupae of the whitefly Bemisia tabaci inhibits the emergence of adults.

The whitefly Bemisia tabaci is a major pest to agriculture. Adults are able to fly for long distances and to colonize staple crops, herbs and ornamentals, and to vector viruses belonging to several important taxonomic groups. During their early development, whiteflies mature from eggs through several nymphal stages (instars I to IV) until adults emerge from pupae. We aim at reducing whitefly populations by inhibiting the emergence of adults from nymphs. Here we targeted dystrophin, a conserved protein essential for the development of the muscle system in humans, other animals and insects. We have exploited the fact that whitefly nymphs developing on tomato leaves feed from the plant phloem via their stylets. Thus, we delivered dystrophin-silencing double-stranded RNA to nymphs developing on leaves of tomato plantlets with their roots bathing in the silencing solution. Downregulation of dystrophin expression occurred mainly in pupae. Dystrophin silencing induced also the downregulation of the dystrophin-associated protein genes actin and tropomyosin, and disrupted F-actin. Most significantly, the treatment inhibited the emergence of adults from pupae, suggesting that targeting dystrophin may help to restrain whitefly populations. This study demonstrates for the first time the important role of dystrophin in the development of a major insect pest to agriculture.

'Candidatus Liberibacter solanacearum' Is Tightly Associated with Carrot Yellows Symptoms in Israel and Transmitted by the Prevalent Psyllid Vector Bactericera trigonica.

Carrot yellows disease has been associated for many years with the Gram-positive, insect-vectored bacteria, 'Candidatus Phytoplasma' and Spiroplasma citri. However, reports in the last decade also link carrot yellows symptoms with a different, Gram-negative, insect-vectored bacterium, 'Ca. Liberibacter solanacearum'. Our study shows that to date 'Ca. L. solanacearum' is tightly associated with carrot yellows symptoms across Israel. The genetic variant found in Israel is most similar to haplotype D, found around the Mediterranean Basin. We further show that the psyllid vector of 'Ca. L. solanacearum', Bactericera trigonica, is highly abundant in Israel and is an efficient vector for this pathogen. A survey conducted comparing conventional and organic carrot fields showed a marked reduction in psyllid numbers and disease incidence in the field practicing chemical control. Fluorescent in situ hybridization and scanning electron microscopy analyses further support the association of 'Ca. L. solanacearum' with disease symptoms and show that the pathogen is located in phloem sieve elements. Seed transmission experiments revealed that while approximately 30% of the tested carrot seed lots are positive for 'Ca. L. solanacearum', disease transmission was not observed. Possible scenarios that may have led to the change in association of the disease etiological agent with carrot yellows are discussed. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Diversity and localization of bacterial symbionts in three whitefly species (Hemiptera: Aleyrodidae) from the east coast of the Adriatic Sea.

Several whitefly species (Hemiptera: Aleyrodidae) are cosmopolitan phloem-feeders that cause serious damage in numerous agricultural crops. All whitefly species harbor a primary bacterial symbiont and a diverse array of secondary symbionts which may influence several aspects of the insect's biology. We surveyed infections by secondary symbionts in Bemisia tabaci (Gennadius), Trialeurodes vaporariorum (Westwood) and Siphoninus phillyreae (Haliday) from areas in the east cost of the Adriatic Sea. Both the Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) B. tabaci genetic groups were detected in Montenegro, whereas only the MED was confirmed in Croatia. Trialeurodes vaporariorum and S. phillyreae were found in all areas surveyed. MEAM1 and MED exhibited similarity to previously reported infections, while populations of T. vaporariorum from Montenegro harbored Rickettsia, Wolbachia and Cardinium in addition to previously reported Hamiltonella and Arsenopnohus. Siphoninus phillyreae harbored Hamiltonella, Wolbachia, Cardinium and Arsenophonus, with the latter appearing in two alleles. Multiple infections of all symbionts were common in the three insect species tested, with some reaching near fixation. Florescent in situ hybridization showed new localization patterns for Hamiltonella in S. phillyreae, and the morphology of the bacteriosome differed from that observed in other whitefly species. Our results show new infections with bacterial symbionts in the whitefly species studied. Infections with the same symbionts in reproductively isolated whitefly species confirm complex relationships between whiteflies and bacterial symbionts, and suggest possible horizontal transfer of some of these bacteria.

Integrating amperometric detection with electrophoresis microchip devices for biochemical assays: recent developments.

Recent advances in microfluidic systems, particularly in the Micro Total Analysis System (µTAS) or Lab On a Chip (LOC), drive the current analysis tools and equipment towards miniaturization, rapid at-line testing and mobility. The state-of-the-art microfluidic technology targets a wider range but smaller volumes of analytes, making the analytical procedure relatively easier and faster. This trend together with faster electronics and modern instrumentation systems will make real-time and in situ analysis a definite possibility. This review focuses on microchip capillary electrophoresis with amperometric detection (MCE-AD) for the detection of DNA and other electroactive analytes. The problems associated with the microchip design, in particular the choice of materials and the configuration of electrodes are discussed thoroughly and solutions are proposed. Significant developments in the related areas are also covered and reviewed critically.

Intranasal administration of NECA can induce both anti-inflammatory and pro-inflammatory effects in BALB/c mice: evidence for A 2A receptor sub-type mediation of NECA-induced anti-inflammatory effects.

The role of adenosine in allergic inflammation is unclear. This study investigated the effects of the non-selective adenosine receptor agonist, 5-N-ethylcarboxamidoadenosine (NECA), on immunized only and immunized and airway challenged mice. The adenosine receptor sub-type(s) mediating the NECA effects and the A(2A) receptor mRNA expression were also investigated. In mice that were only immunized, intranasal NECA (1 mM) administration caused a significant increase in bronchoalveolar lavage total cell count (TCC), neutrophils and eosinophils (>1.5-, >6 and >60-fold, respectively). Two and four intranasal ovalbumin (OVA) challenges induced a significant (P < 0.05) increase in TCC (>2.1- and >4-fold, respectively) and eosinophils (>350- and >1700-fold, respectively). Real-time PCR analysis showed that the A(2A) receptor sub-type mRNA was significantly increased (P < 0.05) in the lung tissue of immunized mice following both two and four OVA challenges. NECA (0.3 mM) treatment caused a significant reduction in the increase induced by the two and four OVA challenges in the TCC by 46.1% and 56.6%, respectively, eosinophils by 70.1% and 75.6%, respectively, and in the A(2A) receptor sub-type mRNA by 43.2% and 41.0%, respectively. Treatment with the A(2A) receptor antagonist, 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine), SCH-58261, completely reversed both the NECA-mediated reduction in TCC and eosinophilia. Moreover, OVA challenge of immunized mice, over 2 consecutive days, resulted in a significant (P < 0.05) increase in TCC (4.5-fold) and eosinophils (>2000-fold) that was detected 72 h later. NECA (0.3 mM) treatment, at 24 and 48 h post OVA challenge, significantly reduced the increase in both TCC and eosinophils by 45.0% and 74.8%, respectively. Our data show that in immunized, but not OVA-challenged mice, high dose of NECA (1 mM) induces an inflammatory airway response. In contrast, in models of inflammation, NECA, at mainly 0.3 mM, induces a significant anti-inflammatory effect when administered prior to the induction of airway inflammation or therapeutically following its establishment. The data also indicate that the anti-inflammatory action of NECA seems to be mediated via the A(2A) receptor sub-type and hence the use of selective A(2A) receptor agonists as potential therapeutic agents in the treatment of inflammatory diseases such as asthma should be investigated further.

Biotype-dependent secondary symbiont communities in sympatric populations of Bemisia tabaci.

The sweet potato whitefly, Bemisia tabaci, harbors Portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts including Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium and Fritschea, the function of which is unknown. Bemisia tabaci is a species complex composed of numerous biotypes, which may differ from each other both genetically and biologically. Only the B and Q biotypes have been reported from Israel. Secondary symbiont infection frequencies of Israeli laboratory and field populations of B. tabaci from various host plants were determined by PCR, in order to test for correlation between bacterial composition to biotype and host plant. Hamiltonella was detected only in populations of the B biotype, while Wolbachia and Arsenophonus were found only in the Q biotype (33% and 87% infection, respectively). Rickettsia was abundant in both biotypes. Cardinium and Fritschea were not found in any of the populations. No differences in secondary symbionts were found among host plants within the B biotype; but within the Q biotype, all whiteflies collected from sage harboured both Rickettsia and Arsenophonus, an infection frequency which was significantly higher than those found in association with all other host plants. The association found between whitefly biotypes and secondary symbionts suggests a possible contribution of these bacteria to host characteristics such as insecticide resistance, host range, virus transmission and speciation.

Nuclear DNA content of the whitefly Bemisia tabaci (Aleyrodidae: Hemiptera) estimated by flow cytometry.

The nuclear DNA content of the whitefly Bemisia tabaci (Gennnadius) was estimated using flow cytometry. Male and female nuclei were stained with propidium iodide and their DNA content was estimated using chicken red blood cells and Arabidopsis thaliana L. (Brassicaceae) as external standards. The estimated nuclear DNA content of male and female B. tabaci was 1.04 and 2.06 pg, respectively. These results corroborated previous reports based on chromosome counting, which showed that B. tabaci males are haploid and females are diploid. Conversion between DNA content and genome size (1 pg DNA=980 Mbp) indicate that the haploid genome size of B. tabaci is 1020 Mbp, which is approximately five times the size of the genome of the fruitfly Drosophila melanogaster Meigen. These results provide an important baseline that will facilitate genomics-based research for the B. tabaci complex.

Registered blindness and low vision in Kuwait.

AIM: To estimate the incidence rates and major causes of registered blindness and low vision in Kuwait. METHODS: Data on age, gender and cause of blindness and low vision were collected from the Visual Disability Committee while evaluating Kuwaiti citizens applying for a blindness allowance from January 2000 to December 2004. Criteria for legal blindness in Kuwait are visual acuity 6/60 or less in the better eye with best possible correction or a visual field less than 20 degrees around the central fixation point. Incidence rates per 100,000 person years of observation were calculated for both genders in four age subgroups and four severity categories. The causes of registered blindness were classified according to the International Classification of Diseases, 10th edition. RESULTS: 412 persons were registered as blind, 272 males (66.01%) and 140 females (33.98%), mean age 28.7 +/-25.2 years, 39.32% below 20 years of age, 31.79% 21-40 years, 18.68% 41-60 years, and 9.95% 61 years and over . Male gender was prevalent for all age subgroups. The overall incidence rate was 9.97 per 100,000 person years of observation, 13.33 for the male and 6.69 for the female patients. The incidence rates rose from 7.35 for those 20 years and younger to 14.80 for the age subgroup 41-60 and 23.16 for those 61 years and above. The rates of severe visual impairment classified in categories 4 and 5 were higher than the rates for categories 2 and 3. Retinitis pigmentosa was the leading cause of blindness, followed by congenital anomalies and optic atrophy. In the subgroup below 20 the rate of optic atrophy was highest, followed by congenital malformations, retinitis pigmentosa and retinopathy of prematurity. In the next age subgroup (21-40 years), the rate of retinitis pigmentosa was three times as high as in the younger subgroup, followed by optic atrophy, congenital malformations and albinism. In the subgroup 41-60 the incidence rate for phthisis bulbi was twice as high as the rates for retinitis pigmentosa and optic atrophy. For those 61 years and older, the incidence rate of phthisis bulbi was almost five times as high as that for optic atrophy. The incidence rates for the male patients were higher for the major causes of disability in all age subgroups. CONCLUSIONS: The overall incidence rate of registered blindness for Kuwait is less than in many other national registries. The marked prevalence of the male gender in all age subgroups is specific for Kuwait. The rates of the leading causes of registered blindness reflect the prevalence of the younger subgroups in our registry. Additional data on co-morbidity and dedicated efforts to reveal unrecognized and unregistered blindness, particularly among females, will overcome the limitations of the registry, and will serve to outline the tendencies in avoidable vision loss and monitor the efficacy of the prevention programs in the future.

Primary hepatic carcinoid tumor.

OBJECTIVES: To describe a rare case of primary carcinoid tumor of the liver and its management. CLINICAL PRESENTATION AND INTERVENTIONS: A 44-year-old Nigerian male presented with a big inoperable liver mass, which proved to be a carcinoid tumor by fine needle aspiration cytology. Extensive search for a primary lesion including laparotomy and peroperative ultrasound failed to find a primary lesion in the gastrointestinal tract and pancreas. Percutaneous embolization of the tumor followed by complete dearterializations of the liver seemed to have halted the growth of the tumor. The patient remained well with normal liver function tests for 56 months when he decided to go back to his country. CONCLUSION: The result showed that dearterializations of a primary inoperable carcinoid of the liver offered good palliation.

Digestive, salivary, and reproductive organs of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type.

A microscopic analysis of the morphology and ultrastructure of the digestive, salivary, and reproductive systems of adult Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type was conducted using light, scanning, and transmission electron microscopy. The internal anatomy of B. tabaci was found to be similar to that reported for Trialeurodes vaporariorum. In a microscopic analysis of the salivary glands, we have shown that each primary salivary gland is composed of at least 13 cells varying in morphology and staining differentially, while the accessory salivary glands are composed of four morphologically similar cells. We analyzed the course of the alimentary canal in B. tabaci, demonstrated the internal morphology of the organs, and clarified the location of the filter chamber relative to other organs in the whitefly. Our observations confirm that the pair of structures extending from the connecting chamber are caeca that may aid in fluid movement through the midgut and are not Malpighian tubules, as previously suggested. We confirm an earlier finding that the whitefly lacks Malpighian tubules, having instead specialized Malpighian-like cells within the filter chamber at the juncture with the internal ileum. Finally, we provide the first scanning electron microscopic analysis showing the reproductive organs of B. tabaci. Our investigation provides clarified terminology for several components of the digestive and excretory system. We also provide drawings and micrographs that will aid future researchers in localizing the internal organs of B. tabaci. We expect our analysis to provide a valuable tool for studying B. tabaci / plant virus interactions and physiological and biological aspects of this insect.

Rate of Tomato yellow leaf curl virus Translocation in the Circulative Transmission Pathway of its Vector, the Whitefly Bemisia tabaci.

ABSTRACT Whiteflies (Bemisia tabaci, biotype B) were able to transmit Tomato yellow leaf curl virus (TYLCV) 8 h after they were caged with infected tomato plants. The spread of TYLCV during this latent period was followed in organs thought to be involved in the translocation of the virus in B. tabaci. After increasing acquisition access periods (AAPs) on infected tomato plants, the stylets, the head, the midgut, a hemolymph sample, and the salivary glands dissected from individual insects were subjected to polymerase chain reaction (PCR) without any treatment; the presence of TYLCV was assessed with virus-specific primers. TYLCV DNA was first detected in the head of B. tabaci after a 10-min AAP. The virus was present in the midgut after 40 min and was first detected in the hemolymph after 90 min. TYLCV was found in the salivary glands 5.5 h after it was first detected in the hemolymph. Subjecting the insect organs to immunocapture-PCR showed that the virus capsid protein was in the insect organs at the same time as the virus genome, suggesting that at least some TYLCV translocates as virions. Although females are more efficient as vectors than males, TYLCV was detected in the salivary glands of males and of females after approximately the same AAP.

The GroEL protein of the whitefly Bemisia tabaci interacts with the coat protein of transmissible and nontransmissible begomoviruses in the yeast two-hybrid system.

We have previously suggested that a GroEL homolog produced by the whitefly Bemisia tabaci endosymbiotic bacteria interacts in the insect hemolymph with particles of Tomato yellow leaf curl virus from Israel (TYLCV-Is), ensuring the safe circulative transmission of the virus. We have now addressed the question of whether the nontransmissibility of Abutilon mosaic virus from Israel (AbMV-Is) is related to a lack of association between GroEL and the virus coat protein (CP). Translocation analysis has shown that, whereas TYLCV-Is DNA is conspicuous in the digestive tract, hemolymph, and salivary glands of B. tabaci 8 h after acquisition feeding started, AbMV-Is DNA was detected only in the insect digestive tract, even after 96 h. To determine whether AbMV-Is particles were rapidly degraded in the hemolymph as a result of their inability to interact with GroEL, we have isolated a GroEL gene from B. tabaci and used a yeast two-hybrid assay to compare binding of the CP of TYLCV-Is and AbMV-Is to the insect GroEL. The yeast assay showed that the CPs of the two viruses are able to bind efficiently to GroEL. We therefore suggest that, although GroEL-CP interaction in the hemolymph is a necessary condition for circulative transmission, the nontransmissibility of AbMV-Is is not the result of lack of binding to GroEL in the B. tabaci hemolymph, but most likely results from an inability to cross the gut/hemolymph barrier.

Tomato leaf curl virus from Bangalore (ToLCV-Ban4): sequence comparison with Indian ToLCV isolates, detection in plants and insects, and vector relationships.

Tomato leaf curl virus (ToLCV) is a whitefly (Bemisia tabaci) transmitted geminivirus (family Geminiviridae, genus Begomovirus) causing a destructive disease of tomato in many regions of India, East Asia and Australia. While ToLCV isolates from Australia and Taiwan have a single genomic component (designated DNA-A), those from Northern India have two components (DNA-A and DNA-B). The ToLCV isolates from Southern India (Bangalore) previously cloned seem to have a DNA-A-like monopartite genome. We have used degenerate DNA-A-specific PCR primers to clone the genome of a ToLCV isolate (named ToLCV-Ban4) from field-infected tomato plants growing in Bangalore, India, in 1997. Degenerate DNA-B-specific PCR primers have not allowed to amplify a putative DNA-B from infected tomato, at the time when DNA-B fragments were amplified from plants infected by known bipartite begomoviruses. The full-length 2759 nucleotide-long DNA-A-like viral genome was sequenced. Similarly to other monopartite ToLCV and TYLCV isolates, ToLCV-Ban4 contains six open reading frames, two on the virion strand and four on the complementary strand. Sequence comparisons indicated that ToLCV-Ban4 is similar to the other three isolates from Bangalore previously sequenced, and is closely related to ToLCV-Ban2 (approximately 91% nucleotide sequence identity). Phylogenetic analysis showed that the ToLCV isolates from Bangalore constitute a group of viruses separated from those of Northern India. ToLCV-Ban4 was detected in tomato and in its whitefly vector Bemisia tabaci by one or by a combination of ELISA, Southern blot hybridization and PCR. Parameters of virus acquisition, retention and transmission by the whitefly vector were investigated in the laboratory. Single whiteflies were able to acquire ToLCV-Ban4 from infected tomato and to transmit the virus to tomato test plants, but five insects were necessary to achieve 100% transmission. Minimum acquisition access and inoculation access periods were 10 min and 20 min, respectively. A latent period of 6 h was required for B. tabaci to efficiently infect tomato test plants. Following a 24 h acquisition access period the insect retained its ability to infect tomato test plants for 12 days, but not for its entire life. In one insect/one plant inoculation tests, female whiteflies were more efficient (approximately 95%) than males (approximately 25%) in transmitting the virus.

Tomato yellow leaf curl geminivirus (TYLCV-Is) is transmitted among whiteflies (Bemisia tabaci) in a sex-related manner.

Tomato yellow leaf curl virus (TYLCV) is the name given to a complex of geminiviruses infecting tomato cultures worldwide. TYLCV is transmitted by a single insect species, the whitefly Bemisia tabaci. Herein we show that a TYLCV isolate from Israel (TYLCV-Is) can be transmitted among whiteflies in a sex-dependent manner, in the absence of any other source of virus. TYLCV was transmitted from viruliferous males to females and from viruliferous females to males but not among insects of the same sex. Transmission took place when insects were caged in groups or in couples, in a feeding chamber or on cotton plants, a TYLCV nonhost. The recipient insects were able to efficiently inoculate tomato test plants. Insect-to-insect virus transmission was instrumental in increasing the number of whiteflies capable of infecting tomato test plants in a whitefly population. TYLCV was present in the hemolymph of whiteflies caged with viruliferous insects of the other sex; therefore, the virus follows, at least in part, the circulative pathway associated with acquisition from infected plants. Taken as a whole, these results imply that a plant virus can be sexually transmitted from insect to insect.

Acceptance of prenatal diagnosis for genetic disorders in Lebanon.

Acceptance of prenatal diagnosis and termination of pregnancy in the case of an affected fetus may vary from one country to another, depending on the health system, religious belief, cultural and educational backgrounds of the population. Following a previous study on couples at risk for a haemoglobin disorder in Lebanon, we have here interviewed 90 couples at risk for a variety of genetic disorders, in order to assess their acceptance of prenatal diagnosis and the variables that might influence their choice. Overall, 54 per cent of couples said they would request diagnosis in their next pregnancy, while 26 per cent were opposed to such a procedure. In 87. 5 per cent of cases, the reason for refusal was because of religious conviction against termination of pregnancy. Refusal of prenatal diagnosis was also related to a lower socio-economic background and poorer education. Only 12 per cent of couples were properly aware of their genetic risk. Therefore, for prevention of genetic disorders, the emphasis in countries such as Lebanon has probably to be placed on public awareness about genetic risks, the risks of consanguinity, availability of services, while taking into consideration the personal beliefs of the individuals.

Bartter's syndrome in Arabic children: review of 13 cases.

BACKGROUND: Bartter's syndrome (BS) is an inherited disease of renal potassium wasting characterized by hypokalemic alkalosis, normal blood pressure, vascular insensitivity to pressor agents and elevated plasma concentrations of renin and aldosterone. It is caused by generalized hyperplasia of the juxtaglomerular apparatus at the site of renin production caused by mutations in the Na-K-2Cl cotransporter gene, NKCC2. The objective of our study is to establish the prevalence and incidence of BS in Kuwait and to assess treatment modalities for it. METHODS AND RESULTS: Bartter's syndrome was diagnosed in 13 Kuwaiti children over a 14 year period (1981-1995) with the estimated incidence of 1.7/100,000 live births. The mean age at diagnosis was 9.3 months (range 2-32 months). There were five males and eight females (ratio 1:1.6). The mean duration of follow up was 5.6 years (1-14 years). Both consanguinity and familial history among our patients were high (69 and 54%, respectively). All patients had hypokalemia, hypochloremia with metabolic alkalosis, hyperreninemia and were normotensive. Clinical presentation was essentially similar to that in other series. Eleven patients (85%) had growth failure, two had nephrocalcinosis (15%) and one had renal failure. All patients were treated with supplemental potassium, an aldosterone antagonist (spironolactone) and a prostaglandin synthetase inhibitor (indomethacin or aspirin) sequentially. Significant catch-up of growth (four patients) and increases in serum potassium (eight patients) were recorded after administration of indomethacin therapy. One patient died of severe pneumonia with respiratory failure from hypokalemic myopathy. Clinical presentation, inheritance, complications and therapy of BS are briefly discussed. CONCLUSION: Bartter's syndrome is a rare disease, but should be considered in the differential diagnosis of other disorders with growth failure and/or hypokalemia. Early diagnosis, close follow up and compliance with treatment may lead to appropriate growth and development.

A GroEL homologue from endosymbiotic bacteria of the whitefly Bemisia tabaci is implicated in the circulative transmission of tomato yellow leaf curl virus.

Evidence for the involvement of a Bemisia tabaci GroEL homologue in the transmission of tomato yellow leaf curl geminivirus (TYLCV) is presented. A approximately 63-kDa protein was identified in B. tabaci whole-body extracts using an antiserum raised against aphid Buchnera GroEL. The GroEL homologue was immunolocalized to a coccoid-shaped whitefly endosymbiont. The 30 N-terminal amino acids of the whitefly GroEL homologue showed 80% homology with that from different aphid species and GroEL from Escherichia coli. Purified GroEL from B. tabaci exhibited ultrastructural similarities to that of the endosymbiont from aphids and E. coli. In vitro ligand assays showed that tomato yellow leaf curl virus (TYLCV) particles displayed a specific affinity for the B. tabaci 63-kDa GroEL homologue. Feeding whiteflies anti-Buchnera GroEL antiserum before the acquisition of virions reduced TYLCV transmission to tomato test plants by >80%. In the haemolymph of these whiteflies, TYLCV DNA was reduced to amounts below the threshold of detection by Southern blot hybridization. Active antibodies were recovered from the insect haemolymph suggesting that by complexing the GoEL homologue, the antibody disturbed interaction with TYLCV, leading to degradation of the virus. We propose that GroEL of B. tabaci protects the virus from destruction during its passage through the haemolymph.