Amino acid substitution equivalent to human chorea-acanthocytosis I2771R in yeast Vps13 protein affects its binding to phosphatidylinositol 3-phosphate

The rare human disorder chorea-acanthocytosis (ChAc) is caused by mutations in hVPS13A gene. The hVps13A protein interacts with actin and regulates the level of phosphatidylinositol 4-phosphate (PI4P) in the membranes of neuronal cells. Yeast Vps13 is involved in vacuolar protein transport and, like hVps13A, participates in PI4P metabolism. Vps13 proteins are conserved in eukaryotes, but their molecular function remains unknown. One of the mutations found in ChAc patients causes amino acids substitution I2771R which affects the localization of hVps13A in skeletal muscles. To dissect the mechanism of pathogenesis of I2771R, we created and analyzed a yeast strain carrying the equivalent mutation. Here we show that in yeast, substitution I2749R causes dysfunction of Vps13 protein in endocytosis and vacuolar transport, although the level of the protein is not affected, suggesting loss of function. We also show that Vps13, like hVps13A, influences actin cytoskeleton organization and binds actin in immunoprecipitation experiments. Vps13-I2749R binds actin, but does not function in the actin cytoskeleton organization. Moreover, we show that Vps13 binds phospholipids, especially phosphatidylinositol 3-phosphate (PI3P), via its SHR_BD and APT1 domains. Substitution I2749R attenuates this ability. Finally, the localization of Vps13-GFP is altered when cellular levels of PI3P are decreased indicating its trafficking within the endosomal membrane system. These results suggest that PI3P regulates the functioning of Vps13, both in protein trafficking and actin cytoskeleton organization. Attenuation of PI3P-binding ability in the mutant hVps13A protein may be one of the reasons for its mislocalization and disrupted function in cells of patients suffering from ChAc.

Phosphatidylinositol-3-phosphate regulates response of cells to proteotoxic stress

Human Nedd4 ubiquitin ligase, or its variants, inhibit yeast cell growth by disturbing the actin cytoskeleton organization and dynamics, and lead to an increase in levels of ubiquitinated proteins. In a screen for multicopy suppressors which rescue growth of yeast cells producing Nedd4 ligase with an inactive WW4 domain (Nedd4w4), we identified a fragment of ATG2 gene encoding part of the Atg2 core autophagy protein. Expression of the Atg2-C1 fragment (aa 1074-1447) improved growth, actin cytoskeleton organization, but did not significantly change the levels of ubiquitinated proteins in these cells. The GFP-Atg2-C1 protein in Nedd4w4-producing cells primarily localized to a single defined structure adjacent to the vacuole, surrounded by an actin filament ring, containing Hsp42 and Hsp104 chaperones. This localization was not affected in several atg deletion mutants, suggesting that it might be distinct from the phagophore assembly site (PAS). However, deletion of ATG18 encoding a phosphatidylinositol-3-phosphate (PI3P)-binding protein affected the morphology of the GFP-Atg2-C1 structure while deletion of ATG14 encoding a subunit of PI3 kinase suppressed toxicity of Nedd4w4 independently of GFP-Atg2-C1. Further analysis of the Atg2-C1 revealed that it contains an APT1 domain of previously uncharacterized function. Most importantly, we showed that this domain is able to bind phosphatidylinositol phosphates, especially PI3P, which is abundant in the PAS and endosomes. Together our results suggest that human Nedd4 ubiquitinates proteins in yeast and causes proteotoxic stress and, with some Atg proteins, leads to formation of a perivacuolar structure, which may be involved in sequestration, aggregation or degradation of proteins.

Sensilla coeloconica ringed by microtrichia in host-seeking biting midges

The distribution and morphology of antennal sensilla coeloconica in parasitic and predaceous biting midges were studied in females of Forcipomyia (feeding on the blood of frogs), Atrichopogon (feeding on haemolymph), Austroconops, Culicoides (feeding on the blood of birds and mammals) and Brachypogon (feeding on haemolymph and dissolved tissues of insects) (all: Diptera: Ceratopogonidae). A Lower Cretaceous female of Archiculicoides (Diptera: Ceratopogonidae) from Lebanese amber, which fed on the blood of unknown vertebrates, was also examined. In sensilla coeloconica ringed by microtrichia, the peg is grooved longitudinally and protrudes distinctly from the pit. We suggest that the microtrichia encircling the protruding peg form a structure resembling a picket fence in order to maintain a higher level of humidity, which facilitates the capture and transport of odour molecules through the channels in the peg wall. Sensilla coeloconica ringed by microtrichia function as very effective chemoreceptors in host- and prey-seeking activity. During the evolution of Ceratopogonidae, sensilla coeloconica with a fence of microtrichia have evolved twice in groups feeding on the blood of vertebrates (i.e. in the basal lineage: Lower Cretaceous or earlier) and in the subgenus Lasiohelea of Forcipomyia (Palaeogene). Sensilla coeloconica ringed by microtrichia are described for the first time in the relict genus Austroconops.

Antimicrobial activity of untypical lipid compounds in the cuticular and internal lipids of four fly species

AIMS

This article describes the qualitative and quantitative analyses of untypical compounds in the cuticular and internal lipids of four dipteran species. For isolated compounds, antimicrobial activity against 18 reference strains of bacteria and fungi was determined.

METHODS AND RESULTS

In this study, gas chromatography (GC) combined with mass spectrometry (GC-MS) was used to analyse the surface and internal compounds of four fly species. Seven untypical compounds from both pre-imaginal and imaginal stages of examined insects were identified. Azelaic acid (AA) was the most abundant, while phenylacetic and phenylpropionic acids occurred in lower concentration. Minor quantities of sebacic acid, 2-methyl-2-hydroxybutanoic acid, tocopherol acetate and trace amounts of 2,4-decadienal were also detected. Tocopherol acetate was found only in cuticular lipids of Musca domestica larvae. Each compound was tested against several species of fungi and bacteria by determining minimal inhibitory concentration (MIC). Human pathogenic fungi were also investigated. Phenylpropionic acid showed the greatest antifungal activity. Bacterial strains were insensitive to the presence of identified compounds, apart from 2,4-decadienal which strongly inhibited bacterial growth.

CONCLUSIONS

This is the first time that the chemical composition and the antimicrobial activity of untypical compounds in the cuticular and internal lipids of four fly species has been analysed.

SIGNIFICANCE AND IMPACT OF THE STUDY

Determination of untypical compounds and their antimicrobial activity can effectively contribute to the knowledge concerning insect defence mechanisms.

[Organization and evolution of animal colonies]

Based on the theory of organization and evolution of colonies in an extinct group of hemichordates graptolites (Urbanek, 1960, 1973) the relationship between the events in the late astogeny of bryozoan colonies and their somatic and reproductive cycle. The bryozoan colonies with simple organization are compared with graptoloid colonies and their structure is interpreted within the framework of the morphogen gradient theory. A morphogen produced by the founder-zooid (oozooid) diffuses along the long axis of the colonies and regulates the phenotypic expression of the size and structure of zooids. Evolutionary changes in the graptoloid colonies involve introduction of new characters and their spreading is also accompanied by gradient changes of their manifestation. Evolutionary mechanisms in bryozoan colonies are considered in terms of penetrance and expressivity of genes. In contrast to graptolites, many bryozoan colonies display multiple zones of astogeny changes and repetitions.

Knowledge and attitude assessment of Quebec daycare workers and parents regarding HIV/AIDS and hepatitis B

ISSUES

Cases of discrimination occur in Quebec daycares towards HIV-positive children as well as HIV-negative children born to seropositive parents.

OBJECTIVES

Offer three-hour information sessions on bloodborne diseases, specifically HIV and hepatitis B, universal precautions, as well as legal, ethical and psychosocial aspects of HIV/AIDS to: 1) ensure that daycare workers have basic medical information on transmission of HIV and other bloodborne infections, 2) review basic hygiene including universal precautions, 3) link daycares to HIV/AIDS resources in their communities, and 4) facilitate the development of pro-active daycare policies for the integration of HIV-positive children.

RESULTS

In total, 108 information sessions were given, in which 349 daycares participated. Results show an important difference in terms of knowledge and attitudes of the participants. Of the daycares which participated in the information sessions, 37% have developed their own pro-active policy.

Clinical use of indirect lymphography in different forms of leg edema

Indirect lymphography by subepidermal infusion of newly developed nonionic, dimeric contrast media (e.g., Iotrolan) opacifies peripheral lymphatics of the skin. Using this method we examined 159 patients with primary and secondary lymphedema, chronic venous insufficiency, and lipedema and compared the findings to normal individuals. A variety of characteristic patterns were uncovered. The technique causes little patient discomfort and takes on the average only 30 minutes.

[Sonography of acute cholecystitis. A report on 58 cases with a correlation of pathomorphological and histological findings]

Sonography has become the method of choice for evaluating acute diseases of the right upper quadrant. Prior to the ultrasound the diagnosis of acute cholecystitis was based on clinical and laboratory data. The pathohistomorphology of 58 opertively and histologically proven cases of acute cholecystitis has been correlated with preoperative sonography. An acute cholecystitis can be diagnosed based on the following sonographic criteria: Thickening of the wall of the gallbladder to more than 4 mm, sonolucent areas in or around the wall of the gallbladder, an increased ap. diameter of more than 4 cm as well as gallstones. A hyperechoic content of the gallbladder correlating to an empyema of the gallbladder was found in 31% and a perforation in 27.6% of the cases.

[Endoscopic incision of the pancreatic duct]

Concrements in the prepapillary portion of the Wirsungian duct result in secretion with simultaneous obstruction and, thus, represent a potential cause of pancreatitis. The removal of these concrements is indicated and rendered possible by endoscopic incision of the pancreatic duct. This procedure has been performed only very rarely up to the present. Its efficacy is demonstrated by a case report.

The dermal lymphatics in lymphoedema visualized by indirect lymphography

Iotasul, a new water-soluble contrast medium, is very suitable for subepidermal infusion (indirect lymphography) for the demonstration of small (initial) dermal lymphatics in the macro-range (precollectors). By this method normal lymph vessels can be demonstrated in the healthy skin of hands and feet which are so fine that they cannot be punctured for direct lymphography. We studied thirty-eight patients with various forms of lymphoedema by indirect lymphography. In patients with congenital lymphoedema (particularly Milroy's disease) the initial dermal lymphatics in the lymphoedematous region were absent but large lymph collectors were present. Hyperplasia of dermal lymphatics in the form of an extremely fine net was seen in most patients with lymphoedema praecox and tardum. In some forms of primary lymphoedema the defect may be in the initial dermal lymphatics. In secondary lymphoedema, the changes in the peripheral lymphatics (mainly distension and congestion) are apparently a consequence of the primary lesion in the lymph nodes and large collectors. Indirect lymphography might be useful for the early diagnosis of mild lymphoedema and for excluding patients with hypoplasia of initial lymph vessels from surgery.

Differential diagnosis of lymphedema after indirect lymphography with Iotasul

Indirect lymphography with Iotasul (interdigital, intradermal infusion) was performed in 32 patients with lymphedema. No side effects were observed. Opacification of the peripheral lymph vessels reveals two distinct patterns: 1. No, few, or only very small-calibre lymph vessels ("hypoplasia"): 17 patients (primary lymphedema in 14 cases, secondary in 3). 2. Many large-calibre (dilated) lymph vessels ("hyperplasia"): 15 patients (primary lymphedema in 2 cases, secondary in 13). An occasional finding in "hypoplasia" is drainage of the contrast material in the region of the adventitia of vessels, and a network of extremely fine lymph vessels apparently corresponding to the dermal plexus is sometimes observed. Because it leads to the opacification of barely perceptible lymph vessels in the extreme periphery which were previously inaccessible to radiology, indirect lymphography offers a genuine gain in information and improves the differential diagnosis. When administered correctly, Iotasul invariably enhances the peripheral lymph vessels without making any great demands of the patient or investigator.

[New aspects on diagnosis and therapy of primary hyperparathyroidism (author's transl)]

26, out of them 20 surgically proven cases of primary hyperparathyroidism are presented. The value of different laboratory, radiographic and scintigraphic analysis is examined. The estimation of calcium and phosphate in serum, the iPTH-determination and fine detail hands radiographs were found to be sufficient to establish diagnosis and indication for surgery. The chloride/phosphate-ratio proved valuable in comparative statistical analysis between pHPT and two control groups. Venous sampling at present seems to be the superior method for preoperative localization of parathyroid disease. It should be performed before second surgical intervention in the cervical region, in elderly (more than 60 years old) and risk patients. Early diagnosis and therapy of pHPT is important as pHPT is a chronic disease with many organ complications. The value of calcium-screening in an age group between 40 and 60 years is discussed.

[Application of vasopressin in diagnostic radiology (author's transl)]

Vasopressin is demonstrated in 100 selected patients as a suitable drug to remove intestinal gas in diagnostic radiology. After subcutaneous injection of 10 IU Vasopressin only slight side-effects occurred in 35% of the patients. Under strict attention of the contraindications the use of Vasopressin is nearly without risk and leads to partially excellent results.