Bioactivities of alternative protein sources and their potential health benefits.

Increasing the utilisation of plant proteins is needed to support the production of protein-rich foods that could replace animal proteins in the human diet so as to reduce the strain that intensive animal husbandry poses to the environment. Lupins, quinoa and hempseed are significant sources of energy, high quality proteins, fibre, vitamins and minerals. In addition, they contain compounds such as polyphenols and bioactive peptides that can increase the nutritional value of these plants. From the nutritional standpoint, the right combination of plant proteins can supply sufficient amounts of essential amino acids for human requirements. This review aims at providing an overview of the current knowledge of the nutritional properties, beneficial and non-nutritive compounds, storage proteins, and potential health benefits of lupins, quinoa and hempseed.

IRF4 Deficiency Leads to Altered BCR Signalling Revealed by Enhanced PI3K Pathway, Decreased SHIP Expression and Defected Cytoskeletal Responses.

The graded expression of transcription factor interferon regulatory factor 4 (IRF4) regulates B cell development and is critical for plasma cell differentiation. However, the mechanisms, by which IRF4 elicits its crucial tasks, are largely unknown. To characterize the molecular targets of IRF4 in B cells, we established an IRF4-deficient DT40 B cell line. We found that in the absence of IRF4, the expression of several molecules involved in BCR signalling was altered. For example, the expression of B cell adaptor for PI3K (BCAP) was upregulated, whereas the SHIP (SH2-containing Inositol 5?-Phosphatase) expression was downregulated. These molecular unbalances were accompanied by increased BCR-induced calcium signalling, attenuated B cell linker protein (BLNK) and ERK activity and enhanced activity of PI3K/protein kinase B (Akt) pathway. Further, the IRF4-deficient cells showed dramatically diminished cytoskeletal responses to anti-IgM cross-linking. Our results show that IRF4 has an important role in the regulation of BCR signalling and help to shed light on the molecular mechanisms of B cell development and germinal centre response.

Rifaximin in the treatment of recurrent Clostridium difficile infection.

BACKGROUND: Clostridium difficile can cause severe antibiotic-associated colitis. Conventional treatments with metronidazole and vancomycin improve symptoms, but after discontinuation of treatment, C. difficile infection (CDI) recurs in a number of patients. Rifaximin is a rifamycin-based non-systemic antibiotic that has effect against C. difficile. AIM: To assess the effectiveness of rifaximin in recurrent C. difficile infection. METHODS: We retrospectively evaluated the records of 32 patients who were treated with rifaximin for recurrent C. difficile infection. The symptoms were evaluated 12 weeks after the start of treatment and patient records were followed up until 1 year after treatment. RESULTS: The mean age of the patients was 55 years (median 64, range: 19-84 years). Before the initiation of rifaximin therapy, the patients had undergone, on the average, 4.4 (range: 2-12) antimicrobial courses for C. difficile infection. C. difficile strain typing was performed in 27 patients. Eight (30%) patients had a strain with a DNA profile compatible with the BI/NAP1/027 ribotype. Antibiotic susceptibilities were determined of isolates from 22 patients. Most isolates (68%) had very low MIC-values for rifampin (<0.002 µg/mL) and the highest MIC value was 3.0 µg/mL. Isolates with a DNA profile compatible with the BI/NAP1/027 ribotype had, on the average, higher MICs of rifampin. After 12 weeks 17 (53%) patients had no relapse. The MIC value of rifampin seemed to predict the response to rifaximin treatment. CONCLUSIONS: Rifaximin is a safe treatment for C. difficile infection. It has a reasonable effect in C. difficile infection and it can be considered as an optional treatment for recurrent C. difficile infection.

Expression of LIF and LIF receptor beta in Alzheimer's and Parkinson's diseases.

BACKGROUND: Signaling through the leukemia inhibitory factor (LIF) receptor (LIFR) is crucial for nervous system development. There are few studies concerning the expression of LIF and LIFR in normal and degenerating adult human brain. OBJECTIVES: To study the expression of LIF and LIFR in Alzheimer's disease (AD), Parkinson's disease (PD), and control brains. PATIENTS AND METHODS: LIF and LIFR mRNA copy numbers were determined by quantitative real-time RT-PCR from four brain regions of 34 patients with AD, 40 patients with PD, and 40 controls. Immunohistochemistry was performed in seven PD and in four AD patients and in seven normal controls. RESULTS: In general, the LIF copy numbers were 1 log higher than the LIFR copy numbers. In the AD brains, LIF expression was higher than in the controls in the hippocampus and in the temporal cortex, and in the PD brains in the hippocampus and in the anterior cingulated cortex. Expressions of LIF and LIFR in different brain regions were opposite except for the AD hippocampus and PD anterior cingulated cortex, where the expression patterns were parallel. CONCLUSIONS: Co-operative expression of LIF and LIFR in AD hippocampus and PD anterior cingulated cortex may indicate a role for LIF in neuronal damage or repair in these sites.

A network analysis of the single nucleotide polymorphisms in acute allergic diseases.

BACKGROUND: Genetics of acute allergies has focused on identifying single nucleotide polymorphisms (SNPs) within genes relevant in the pathogenesis. In this study, we begin a systems biology analysis of the interconnectivity and biological functions of these genes, their transcripts and their corresponding proteins. METHODS: The literature (Pubmed) was searched for SNPs within genes relevant in acute allergic diseases. The SNP-modified genes were converted to corresponding proteins and their protein-protein interactions were searched from six different databases. This interaction network was analysed with annotated vocabularies (ontologies), such as Gene Ontology, Reactome and Nature pathway interaction database. Time-series transcriptomics was performed with nasal epithelial cells obtained from allergic patients and their healthy control subjects. RESULTS: A total of 39 genes with SNPs related to acute allergic diseases were found from a literature search. The corresponding proteins were then hooked into a large protein-protein interaction network with the help of various databases. Twenty-five SNP-related proteins had more than one interacting protein and a network contained 95 proteins, and 182 connections could be generated. This network was 10-fold enriched with protein kinases and proteins involved in the host-virus interaction compared with background human proteome. Finally, eight of the 95 nodes on our network displayed nasal epithelial transcriptomal regulation in a time-series analysis collected from birch allergic patients during the spring pollen season. CONCLUSIONS: Signal transduction with special reference to host-virus interactions dominated in the allergy-related protein interaction network. Systems level analysis of allergy-related mutation can provide new insights into pathogenetic mechanisms of the diseases.

Time-series nasal epithelial transcriptomics during natural pollen exposure in healthy subjects and allergic patients.

BACKGROUND: The role of epithelium has recently awakened interest in the studies of type I hypersensitivity. OBJECTIVE: We analysed the nasal transcriptomics epithelial response to natural birch pollen exposure in a time series manner. METHODS: Human nasal epithelial cell swabs were collected from birch pollen allergic patients and healthy controls in winter season. In addition, four specimens at weekly intervals were collected from the same subjects during natural birch pollen exposure in spring and transcriptomic analyses were performed. RESULTS: The nasal epithelium of healthy subjects responded vigorously to allergen exposure. The immune response was a dominating category of this response. Notably, the healthy subjects did not display any clinical symptoms regardless of this response detected by transcriptomic analysis. Concomitantly, the epithelium of allergic subjects responded also, but with a different set of responders. In allergic patients the regulation of dyneins, the molecular motors of intracellular transport dominated. This further supports our previous hypothesis that the birch pollen exposure results in an active uptake of allergen into the epithelium only in allergic subjects but not in healthy controls. CONCLUSION: We showed that birch pollen allergen causes a defence response in healthy subjects, but not in allergic subjects. Instead, allergic patients actively transport pollen allergen through the epithelium to tissue mast cells. Our study showed that new hypotheses can arise from the application of discovery driven methodologies. To understand complex multifactorial diseases, such as type I hypersensitivity, this kind of hypotheses might be worth further analyses.

Effect of adenoidectomy on respiratory function: a randomised prospective study.

OBJECTIVE: Risk of childhood asthma is increased in children with recurrent otitis media. This may be associated with recurrent respiratory tract infections in these children, but the role of adenoidectomy, a frequent operation during childhood, is unknown. Therefore, the role of adenoidectomy in the development of atopy and respiratory function changes characteristic of asthma was evaluated. DESIGN: Randomised controlled study. SETTING: Tertiary care centre. PATIENTS: 166 children aged 12-48 months who had recurrent or persistent otitis media and who were followed-up for 3 years after randomisation. INTERVENTION: Randomisation to undergo insertion of tympanostomy tubes with or without adenoidectomy. MAIN OUTCOME MEASURES: The primary outcome measure was exercise-induced bronchoconstriction as evaluated by impulse oscillometry. The secondary outcome measures were bronchial inflammation as evaluated by exhaled nitric oxide and atopy as evaluated by skin prick tests. During the 3-year follow-up period otitis media episodes were documented in patient diaries. RESULTS: Adenoidectomy did not significantly influence baseline lung function, exercise-induced bronchoconstriction, exhaled nitric oxide concentration, the development of positive skin prick tests, or doctor-diagnosed asthma. Adenoidectomy did not significantly prevent otitis media. Recurrent otitis media (>or=4 episodes) during the first follow-up year was associated with an abnormal exercise-induced bronchoconstriction (OR 6.62, 95% CI 1.27 to 34) and an elevated exhaled nitric oxide concentration (OR 3.26, 95% CI 0.98 to 10.8) regardless of adenoidectomy. CONCLUSIONS: Adenoidectomy did not promote asthma or allergy. Recurrent respiratory tract infections during early childhood are associated with the risk of bronchial hyper-reactivity.

Birch pollen allergen Bet v 1 binds to and is transported through conjunctival epithelium in allergic patients.

BACKGROUND: Previous work in type-I pollen allergies has mainly focused on lymphocytes and immune responses. Here, we begin to analyse with a systems biology view the differences in conjunctival epithelium obtained from healthy and allergic subjects. METHODS: Transcriptomics analysis combined with light and electron microscopic analysis of birch pollen allergen Bet v 1 located within conjunctival epithelial cells and tissues from birch allergic subjects and healthy controls was carried out. RESULTS: Bet v 1 pollen allergen bound to conjunctival epithelial cells within minutes after the exposure even during the nonsymptomatic winter season only in allergic, but not in healthy individuals. Light- and electron microscopy showed that Bet v 1 was transported through the epithelium within lipid rafts/caveolae and reached mast cells only in allergic patients, but not in healthy individuals. Transcriptomics yielded 22 putative receptors expressed at higher levels in allergic epithelium compared with healthy specimens. A literature search indicated that out of these receptors, eight (i.e. 37%) were associated with lipid rafts/caveolae, which suggested again that Bet v 1 transport is lipid raft/caveola-dependent. CONCLUSIONS: We show a clear difference in the binding and uptake of Bet v 1 allergen by conjunctival epithelial cells in allergic vs healthy subjects and several putative lipid raft/caveolar receptors were identified, which could mediate or be co-transported with this entry. The application of discovery driven methodologies on human conjunctival epithelial cells and tissues can provide new hypotheses worth a further analysis to the molecular mechanisms of a complex multifactorial disease such as type-I birch pollen allergy.

A randomized, controlled trial of tonsillectomy in periodic fever, aphthous stomatitis, pharyngitis, and adenitis syndrome.

OBJECTIVE: We carried out a prospective, randomized, controlled trial to clarify the effect of tonsillectomy on the clinical course of periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome. STUDY DESIGN: Twenty-six consecutive children (mean age 4.1 years) with at least 5 PFAPA attacks were recruited from 3 tertiary care pediatric hospitals during 1999-2003 and randomly allocated to tonsillectomy or follow-up alone. They were all followed up with symptom diaries for 12 months. Tonsillectomy was allowed after 6 months in the control group if the attacks recurred. RESULTS: Six months after randomization all 14 children in the tonsillectomy group and 6/12 children in the control group (50%) were free of symptoms (difference 50%, 95% confidence interval 23% to 75%, P < .001). Tonsillectomy was performed on 5/6 of the patients in the control group who still had symptoms after 6 months. The remaining unoperated child in the control group had recurrences of the fever episodes throughout the follow-up, but the symptoms became less severe, and the parents did not choose tonsillectomy. CONCLUSION: Tonsillectomy appeared to be effective for treating PFAPA syndrome. The fever episodes ceased without any intervention in half of the control subjects. We conclude that although the mechanisms behind this syndrome are unknown, tonsillectomy can be offered as an effective intervention for children with PFAPA.

Human primary adenotonsillar naïve phenotype CD45RA CD4 T lymphocytes undergo apoptosis upon stimulation with a high concentration of CD3 antibody.

Young children need to develop immune tolerance to harmless foreign antigens such as digested nutrients and various inhaled airborne antigens. Because of its anatomical location, pharyngeal adenotonsillar tissue is a potential site for the establishment of this immune tolerance. To characterize possible mechanisms of peripheral immune tolerance, we studied human primary adenotonsillar naïve phenotype CD45RA(+) CD4(+) T cells, which represent cells that have not previously encountered foreign antigens. It was found that these CD45RA(+) CD4(+) T cells expressed higher levels of the activation marker CD69 as compared with peripheral blood CD45RA(+) CD4(+) T cells. Upon stimulation with a high concentration of CD3 antibody, which mimics the encounter of a high antigen dose, adenotonsillar CD45RA(+) CD4(+) T lymphocytes, but not peripheral blood CD45RA(+) CD4(+) T cells, underwent apoptosis. After 6 h stimulation with a high concentration of CD3 antibody, over 25% of the cells were apoptotic. Interfering with the Fas-FasL interaction with recombinant Fas or an antibody against Fas-ligand partially inhibited apoptosis. Our study results suggest that high concentrations of antigens, such as various nutrients and airborne antigens, may induce peripheral immune tolerance by selectively deleting naïve phenotype CD45RA(+) CD4(+) T cells via T-cell receptor-triggered apoptosis in human adenotonsillar tissue.

Analysis of risk factors for childhood persistent middle ear effusion.

Although exposure to infectious agents and parental smoking are known to influence the overall risk of otitis media, these risk factors do not appear to be linked with the tendency to develop chronic otitis media with effusion (COME) instead of recurrent acute otitis media (RAOM). The genetic inflammatory response type of the child appears to influence the risk of persistent middle ear effusion in COME. Two different clinical presentations of childhood otitis media are encountered: RAOM; and COME, which is associated with persistent effusion in the middle ear. The objective of this study was to assess putative factors that may regulate the development of persistent middle ear effusion in COME. In total, 159 children with RAOM and their parents (n=304), and 55 children with COME and their parents (n=110) were evaluated. All the children with COME or RAOM were aged <4 years. There was no difference in the frequency of attendance at day care outside the home, number of siblings or parental smoking between children with RAOM and those with COME. The frequency of parental allergy and asthma was lower among children with COME than those with RAOM.

Reactive oxygen species induce signals that lead to apoptotic DNA degradation in primary CD4+ T cells.

Reactive oxygen species are toxic to cells but they may also have active roles in transducing apoptotic events. To study the role of reactive oxygen species in growth factor depletion induced apoptosis of human primary CD4+ T cells, we used a synthetic manganese porphyrin superoxide dismutase mimetic to detoxify superoxide anions formed during apoptosis. Apoptosis of primary CD4+ T cells was characterized by generation of superoxide anions, plasma membrane phosphatidyl-serine translocation, loss of mitochondrial membrane potential, activation of caspase 3, condensation of chromatin, as well as DNA degradation. The detoxification of superoxide anions did not influence plasma membrane phosphatidyl-serine translocation, or chromatin condensation, and only marginally inhibited the loss of mitochondrial membrane potential and the formation of DNA strand breaks. In contrast, the detoxification of superoxide anions significantly reduced caspase 3 activity and almost completely inhibited the apoptotic decrease in total cellular DNA content as measured by propidium iodide staining. Our results indicate that reactive oxygen anions induce signals leading to efficient DNA degradation after the initial formation of DNA strand breaks. Thus, reactive oxygen anions have active roles in signaling that lead to the apoptotic events.

Platelet endothelial cell adhesion molecule-1 is expressed in adenoidal crypt epithelial cells.

The adenoidal epithelial crypt is a potential site of antigen transport from pharyngeal lumen to adenoidal tissue. The base of the crypt is consistently infiltrated with leucocytes, forming a reticular lymphoepithelial structure. To evaluate mechanisms that possibly mediate leucocyte infiltration, expressions of leucocyte adhesion molecules, such as platelet endothelial cell adhesion molecule-1 (PECAM-1) (CD31), vascular cell adhesion molecule-1 (VCAM-1) (CD106) and intercellular adhesion molecule-1 (ICAM-1) (CD54), were studied in the adenoidal epithelial crypt. Epithelial cells in the outer opening of the adenoidal crypt were positive for VCAM-1, whereas epithelial cells at the base of the crypt were positive for PECAM-1. Isolated ICAM-1-expressing cells were found throughout the epithelial crypt. Double immunofluorescence staining revealed that the epithelial cells positive for PECAM-1 or VCAM-1 were positive for cytokeratin. The expression of PECAM-1 in the base and VCAM-1 at the orifice of the adenoidal epithelial crypt implies that the base and the orifice of the crypt have a distinct ability to recruit leucocytes. Epithelial cells expressing PECAM-1 may have a role in the formation of the reticular lymphoepithelial structure in the epithelial crypt.

Genoprevalence in human tissues of TT-virus genotype 6.

TT virus (TTV) is a newly discovered human virus of high genotypic diversity. TTV is widely distributed among humans, but the possible genotype-related differences in TTV biology are not well known. The prevalence and amount of TTV-DNA, especially of genotype 6, was determined by nested-PCR in various human tissues, and human parvovirus B19, another ssDNA virus, was used as a reference. TTV DNA was detected simultaneously in bile, peripheral blood mononuclear cells (PBMC) and plasma of 77% subjects, in 38% skin samples, in 38% synovial samples and in all (100%) adenoids, tonsils and liver samples. The relative concentrations of TTV-DNA did not vary significantly among the different samples. Genotype 6 TTV-DNA was detected in bile and plasma of one subject (3%), in skin and serum of one subject (8%) and in one liver (5%). The overall prevalence of TTV genotype 6 was 4% in subjects and 4% in sera. TTV genotype 6 was shown to occur in human tissues with no obvious tissue-type or symptom specificity. Parvovirus B19 DNA was detected overall in 38% subjects, and bile was the only sample type tested that did not persistently harbour B19 DNA.

Effect of vitamin D2- and D3-enriched diets on egg vitamin D content, production, and bird condition during an entire production period.

Vitamin D insufficiency during winter is a common problem for humans in Europe. One way to ease this problem is through the production of vitamin D-fortified eggs. To evaluate such a production process, the effects of vitamin D supplementation during an entire production period were assessed. Transfer of vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) from the diet to egg yolks was measured using 2 different levels of both vitamins (6,000 and 15,000 IU/kg feed) relative to a control treatment (2,500 IU vitamin D3/kg feed). During the experiment, production parameters, egg quality (egg weight, Haugh unit, specific gravity, eggshell fracture force, and Ca content of eggshell), and the condition of hens were monitored. At the end of the experiment histopathological tests were performed. Supplementing diets with vitamin D3 increased egg yolk vitamin D content more effectively than did supplementation with vitamin D2. For groups of hens receiving 6,000 or 15,000 IU of vitamin D3/kg feed, egg yolk vitamin D3 content ranged from 9.1 to 13.6 and from 25.3 to 33.7 microg/100 g, respectively. Corresponding values for birds fed vitamin D2 were 4.7 to 7.0 and 13.3 to 21.0 microg/100 g. Both supplements enhanced vitamin D3 content of egg yolks relative to the control diet (2.5 to 5.0 microg/100 g of egg yolk). Vitamin D supplements had no effects on production parameters compared with the control diet. However, especially vitamin D3 improved bone strength (P < 0.05). Autopsy at the end of the experiment indicated no detrimental accumulation of calcium in the kidneys, liver, heart, muscles, or lungs.

High incidence of PTLD after non-T-cell-depleted allogeneic haematopoietic stem cell transplantation as a consequence of intensive immunosuppressive treatment.

The occurrence of post-transplant lymphoproliferative disorder (PTLD) in relation to immunosuppressive treatment was determined in 257 patients treated with non-T-cell-depleted allogeneic stem cell transplantation from an HLA-matched sibling (173 patients) or unrelated donor (84 patients). The conditioning consisted of total body irradiation and cyclophosphamide (myeloablative conditioning, 250 patients), or fludarabine combined with cyclophosphamide or a single 2 Gy dose of TBI (nonmyeloablative conditioning, seven patients). In transplantations from an unrelated donor, the patients also received antithymocyte globulin (ATG). The prophylaxis against graft-versus-host disease (GVHD) consisted of cyclosporine A, methotrexate, and methylprednisolone. The autopsy reports of deceased patients were systematically reviewed, and the autopsy materials of cases suggestive of PTLD were re-examined histologically for Epstein-Barr virus (EBV). Nineteen patients with EBV-positive PTLD were identified, of whom six had been transplanted from a sibling donor and 13 from an unrelated donor. All the patients who developed PTLD had been given ATG either for the treatment of steroid-resistant acute GVHD (all PTLD patients with a sibling donor and one with an unrelated donor), or as part of the conditioning (all patients with an unrelated donor). In conclusion, in transplantations from an HLA-identical donor with a non-T-cell-depleted graft, the risk of PTLD correlated strongly with the intensity of the immunosuppressive treatment.

Improved bone biomechanical properties in xylitol-fed aged rats.

Our previous studies have shown that dietary xylitol protects against weakening of bone biomechanical properties in experimental postmenopausal osteoporosis. To study whether xylitol preserves bone biomechanics also during aging, a long-term experimental study was performed with rats. Twenty-four male Sprague-Dawley rats were divided into 2 groups. The rats in the control group (NON-XYL group) were fed a basal rat and mouse no. 1 maintenance (RM1) diet, while the rats in the experimental group (XYL group) were continuously fed the same diet supplemented with 10% xylitol (wt/wt). The rats were killed after 20 months. Their femurs were prepared for biomechanical analyses and scanning analyses with peripheral quantitative computed tomography (pQCT). In 3-point bending of the femoral diaphysis, maximum load, maximum elastic load, stiffness, energy absorption, elastic energy absorption, ultimate stress, and yield stress were significantly greater in the XYL group than in the NON-XYL group. This indicates a xylitol-induced improvement of both structural and material strength properties of cortical bone. Accordingly, the maximum load of femoral neck was significantly greater in the XYL group. In the pQCT analysis of femoral diaphysis, cortical bone area, cortical thickness (CtTh) periosteal circumference, and cross-sectional moment of inertia were greater in the XYL group. The endosteal circumference was smaller in the XYL group. In the pQCT analysis of the femoral neck cortical area of the midneck was significantly greater in the XYL group. This data indicates that xylitol exerted beneficial effects on the cross-sectional architecture of the bones. In conclusion, continuous moderate dietary xylitol supplementation leads to improved bone biomechanical properties in aged rats concerning both bone structural and material strength properties.

Cloning and expression of Helicobacter pylori GDP-l-fucose synthesizing enzymes (GMD and GMER) in Saccharomyces cerevisiae.

Helicobacter pylori is a Gram-negative gastric pathogen causing diseases from mild gastric infections to gastric cancer. The difference in clinical outcome has been suggested to be due to strain differences. H. pylori undergoes phase variation by changing its lipopolysaccharide structure according to the environmental conditions. The O-antigen of H. pylori contains fucosylated glycans, similar to Lewis structures found in human gastric epithelium. These Lewis glycans of H. pylori have been suggested to play a role in pathogenesis in the adhesion of the bacterium to gastric epithelium. In the synthesis of fucosylated structures, GDP-l-fucose is needed as a fucose donor. Here, we cloned the two key enzymes of GDP-l-fucose synthesis, H. pylori gmd coding for GDP-d-mannose dehydratase (GMD), and gmer coding for GDP-4-keto-6-deoxy-d-mannose-3,5-epimerase/4-reductase (GMER) and expressed them in an enzymatically active form in Saccharomyces cerevisiae. The end product of these enzymes, GDP-l-fucose was used as a fucose donor in a fucosyltransferase assay converting sialyl-N-acetyllactosamine to sialyl Lewis X.

Twinfilin is required for actin-dependent developmental processes in Drosophila.

The actin cytoskeleton is essential for cellular remodeling and many developmental and morphological processes. Twinfilin is a ubiquitous actin monomer-binding protein whose biological function has remained unclear. We discovered and cloned the Drosophila twinfilin homologue, and show that this protein is ubiquitously expressed in different tissues and developmental stages. A mutation in the twf gene leads to a number of developmental defects, including aberrant bristle morphology. This results from uncontrolled polymerization of actin filaments and misorientation of actin bundles in developing bristles. In wild-type bristles, twinfilin localizes diffusively to cytoplasm and to the ends of actin bundles, and may therefore be involved in localization of actin monomers in cells. We also show that twinfilin and the ADF/cofilin encoding gene twinstar interact genetically in bristle morphogenesis. These results demonstrate that the accurate regulation of size and dynamics of the actin monomer pool by twinfilin is essential for a number of actin-dependent developmental processes in multicellular eukaryotes.