A novel binary pesticidal protein from Chryseobacterium arthrosphaerae controls western corn rootworm by a different mode of action to existing commercial pesticidal proteins

The western corn rootworm (WCR) Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) remains one of the economically most important pests of maize (Zea mays) due to its adaptive capabilities to pest management options. This includes the ability to develop resistance to some of the commercial pesticidal proteins originating from different strains of Bacillus thuringiensis. Although urgently needed, the discovery of new, environmentally safe agents with new modes of action is a challenge. In this study we report the discovery of a new family of binary pesticidal proteins isolated from several Chryseobacterium species. These novel binary proteins, referred to as GDI0005A and GDI0006A, produced as recombinant proteins, prevent growth and increase mortality of WCR larvae, as does the bacteria. These effects were found both in susceptible and resistant WCR colonies to Cry3Bb1 and Cry34Ab1/Cry35Ab1 (reassigned Gpp34Ab1/Tpp35Ab1). This suggests GDI0005A and GDI0006A may not share the same binding sites as those commercially deployed proteins and thereby possess a new mode of action. This paves the way towards the development of novel biological or biotechnological management solutions urgently needed against rootworms.

Culturing the desert microbiota

Over the last 30 years, the description of microbial diversity has been mainly based on culture-independent approaches (metabarcoding and metagenomics) allowing an in-depth analysis of microbial diversity that no other approach allows. Bearing in mind that culture-dependent approaches cannot replace culture-independent approaches, we have improved an original method for isolating strains consisting of "culturing" grains of sand directly on Petri dishes (grain-by-grain method). This method allowed to cultivate up to 10% of the bacteria counted on the surface of grains of the three sites studied in the Great Western Erg in Algeria (Timoudi, Béni Abbès, and Taghit), knowing that on average about 10 bacterial cells colonize each grain. The diversity of culturable bacteria (collection of 290 strains) predicted by 16S rRNA gene sequencing revealed that Arthrobacter subterraneus, Arthrobacter tecti, Pseudarthrobacter phenanthrenivorans, Pseudarthrobacter psychrotolerans, and Massilia agri are the dominant species. The comparison of the culture-dependent and -independent (16S rRNA gene metabarcoding) approaches at the Timoudi site revealed 18 bacterial genera common to both approaches with a relative overestimation of the genera Arthrobacter/Pseudarthrobacter and Kocuria, and a relative underestimation of the genera Blastococcus and Domibacillus by the bacterial culturing approach. The bacterial isolates will allow further study on the mechanisms of tolerance to desiccation, especially in Pseudomonadota (Proteobacteria).

Human and rodent bone marrow mesenchymal stem cells that express primitive stem cell markers can be directly enriched by using the CD49a molecule

Bone marrow (BM) from human and rodent species contains a population of multipotential cells referred to as mesenchymal stem cells (MSCs). Currently, MSCs are isolated indirectly by using a culture step and then the generation of fibroblast colony-forming units (CFU-fs). Unprocessed or native BM MSCs have not yet been fully characterised. We have previously developed a direct enrichment method for the isolation of MSCs from human BM by using the CD49a protein (alpha1-integrin subunit). As the CD49a gene is highly conserved in mammals, we have evaluated whether this direct enrichment can be employed for BM cells from rodent strains (rat and mouse). We have also studied the native phenotype by using both immunodetection and immunomagnetic methods and have compared MSCs from mouse, rat and human BM. As is the case for human BM, we have demonstrated that all rodent multipotential CFU-fs are contained within the CD49a-positive cell population. However, in the mouse, the number of CFU-fs is strain-dependent. Interestingly, all rat and mouse Sca-1-positive cells are concentrated within the CD49a-positive fraction and also contain all CFU-fs. In human, the colonies have been detected in the CD49a/CD133 double-positive population. Thus, the CD49a protein is a conserved marker that permits the direct enrichment of BM MSCs from various mammalian species; these cells have been phenotyped as true BM stem cells.

Can low frequency sound stimulation during posturography help diagnosing possible perilymphatic fistula in patients with sensorineural hearing loss and/or vertigo?

Perilymphatic fistula (PLF) is often difficult to diagnose because of the similar symptomatology, such as vertigo, tinnitus and hearing loss, which is found in several inner ear diseases. We attempted to correlate a positive result of low frequency sound (LFS) stimulation tests in posturography with the presence or absence of a PLF confirmed by transtympanic endoscopy in 209 patients with various inner ear diseases (Meniere's disease ( n=128), vestibulopathy ( n=41), cochleopathy ( n=28) and sudden deafness ( n=12). LFS provoked unsteadiness in posturography without PLF in 24 patients with Meniere's disease, in 5 patients with vestibulopathy, in 3 patients with cochleopathy and in 2 patients with sudden deafness. In one patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In four cases there was abnormal light reflex in the round window but without PLF. In eight cases, Hennebert's sign was present with nystagmus, without PLF. We conclude that pathological responses to the LFS test in posturography can also be encountered in other inner ear diseases without PLF.

Role of transtympanic endoscopy of the middle ear in the diagnosis of perilymphatic fistula in patients with sensorineural hearing loss or vertigo

BACKGROUND

The diagnosis of perilymphatic fistula (PLF) is often difficult, and therefore the condition can be overlooked. Tympanoscopy presents an alternative procedure for visualising the middle ear anatomy, and it may help to diagnose PLF.

AIM

The aim of this study was to evaluate the use of middle ear endoscopy in establishing the diagnosis of PLF and in defining its incidence in patients with sensorineural hearing loss and/or vertigo and tinnitus.

SUBJECTS AND METHODS

Two hundred and sixty-five patients (22-80 years of age, mean 48 years) were prospectively and consecutively referred for middle ear examination with tympanoscopy. Tympanoscopy was performed using endoscopes with visual angles of 5 and 25 degrees and an outer diameter of 1.7 mm. The round window niche (with its secondary membrane), the oval window with a stapes superstructure, a part of the facial recess and the area in the fissula ante fenestram were examined and video-recorded.

RESULTS

For 1 patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In 4 cases abnormal mucosal shining appeared in the round window, but no PLF was present. In 7 cases the tympanic cavity could not be visualised because of the adhesive tympanic membrane, abnormal anatomy or the prominent exostoses of the external ear canal. In 6 cases a postendoscopic middle ear infection was found. No permanent tympanic membrane perforation occurred in any of the patients in this study.

CONCLUSIONS

Tympanoscopy is a rapid examination tool with which to verify certain areas of the middle ear anatomy, but it is of limited value for ruling out the presence of PLF.

Cochlear blood flow measurement in patients with Ménière's disease and other inner ear disorders

To identify an eventual vascular aetiology in different diseases with sensorineural hearing loss (SNHL), the cochlear blood flow (CoBF) was measured using laser Doppler flowmetry (LDF) in 69 patients with Ménière's disease (MD), 38 patients with progressive SNHL and 8 patients with sudden deafness. The mean CoBF amplitude at rest was 0.70 mV (SD 0.25) for patients with MD, 0.66 mV (SD 0.21) for patients with SNHL and 0.69 mV (SD 0.23) for those with sudden deafness. No statistically significant difference was observed between the groups with respect to the CoBF amplitudes at rest or during the Valsalva manoeuvre. There was a statistically significant correlation (r = -0.4, p < 0.05) between the hearing level and CoBF amplitude in the SNHL group only. It is concluded that the reduction in vascular flow may not be the main aetiological factor in Ménière's disease or sudden deafness. In SNHL the correlation of hearing level with the level of the LDF amplitude can be secondary to the progression of hearing loss.

Middle ear imaging in neurotological work-up

Middle ear imaging constitutes a homogeneous test battery for evaluation of neurotological disease. The imaging comprises infra-sound fistula test, ABR, tympanoscopy, ECoG, and trans-promontiorial cochlear blood flow measurement. We used a fistula test with infra-sound loading on posturography. In tympanoscopy we used 5 degrees and 25 degrees endoscopes with a diameter of 1.9 mm and length of 125 mm. In blood flow measurement we used laser-Doppler system with a stainless steel tip placed on the basal turn against stira vascularis. The flux was analyzed with a computer with custom-made software. In ECoG, a silver ball electrode was placed on the round window. In 64 cases evaluated we were not able to verify a spontaneous PLF by tympanoscopy. Symptoms typical for spontaneous PLF with positive fistula test turned out to be caused by endolymphatic hydrops. Sudden deafness usually did not show reduced cochlear blood flow, but often an endolymphatic hydrops. Fistula test was positive in about 25% of cases with endolymphatic hydrops. Tympanoscopy caused very few complication. The procedure takes about one hour and is done ambulatorily.