Evidence that Xylella fastidiosa is the Causal Agent of Almond Leaf Scorch Disease in Alicante, Mainland Spain (Iberian Peninsula).

In 2017, Xylella fastidiosa, a quarantine plant-pathogenic bacterium in Europe, was detected in almond trees associated with leaf scorch symptoms in Alicante, a Mediterranean area in southeastern mainland Spain. The bacterium was detected by serological and molecular techniques, isolated in axenic culture from diseased almond trees, and identified as X. fastidiosa subsp. multiplex sequence type (ST) 6. Inoculation experiments on almond plants in greenhouse trials with a characterized strain of X. fastidiosa subsp. multiplex ST6 isolated in the outbreak area have proved that it was able to multiply and systemically colonize inoculated plants. Disease symptoms characteristic of leaf scorch like those observed in the field were observed in the inoculated almond trees after 1 year. Furthermore, the pathogen was reisolated and identified by molecular tests. With the fulfillment of Koch's postulates, we have demonstrated that X. fastidiosa is the causal agent of the almond leaf scorch disease in the Alicante outbreak.

An engineered PET depolymerase to break down and recycle plastic bottles.

Present estimates suggest that of the 359 million tons of plastics produced annually worldwide1, 150-200 million tons accumulate in landfill or in the natural environment2. Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging3. The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties4. Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units-which reduce chain mobility-PET is a polyester that is extremely difficult to hydrolyse5. Several PET hydrolase enzymes have been reported, but show limited productivity6,7. Here we describe an improved PET hydrolase that ultimately achieves, over 10 hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200 grams per kilogram of PET suspension, with an enzyme concentration of 3 milligrams per gram of PET). This highly efficient, optimized enzyme outperforms all PET hydrolases reported so far, including an enzyme8,9 from the bacterium Ideonella sakaiensis strain 201-F6 (even assisted by a secondary enzyme10) and related improved variants11-14 that have attracted recent interest. We also show that biologically recycled PET exhibiting the same properties as petrochemical PET can be produced from enzymatically depolymerized PET waste, before being processed into bottles, thereby contributing towards the concept of a circular PET economy.

The use of clostridial spores for cancer treatment.

Hypoxic/necrotic regions, absent in normal tissues, can be exploited to target tumours in cancer therapy using nonpathogenic strains of the bacterial genus Clostridium. Following administration of Clostridium spores to tumour-bearing organisms, these spores can only germinate within the hypoxic/necrotic regions of solid tumours, proving their exquisite selectivity. Low oxygen tension is a common feature of solid tumours, which may arise from the unique physiological environment, generated to a large extent by the abnormal tumour vasculature, and provides as such a niche for anaerobic bacteria. Some clostridia tested clearly showed innate oncolytic activity, but they could not completely eradicate the tumour. Recombinant clostridia producing prodrug-converting enzymes or cytokines resulted in the production of such proteins solely within the tumour, and where applicable, could convert the prodrug in a toxic compound. Moreover, in some cases, tumour eradication or tumour control could be observed. This review brings an overview of the relative successes and failures of the Clostridium-directed tumour therapy with both wild-type strains and strains producing proteins useful in antitumour therapy.

Tumor-specific gene delivery using genetically engineered bacteria.

The loco-regional control of cancer remains a major contributor to the treatment outcome for many cancer patients prescribed conventional radiotherapy or chemotherapy. Failure of treatment coupled with the realisation that cancer is essentially a genetic disease has led to development of many clinical protocols based on gene therapy. In this review, we will describe an alternative gene delivery system based on the use of non-pathogenic bacteria. Tumor regressions have been reported long ago in patients with bacterially infected tumors, suggesting that bacteria could target tumors and have local anti-tumor effects. The basis of this phenomenon is attributable to the unique properties of the tumor micro-environment. The presence of hypoxic and/or necrotic areas provides a haven for a number of anaerobic bacteria and over the past 60 years, several strains of anaerobic bacteria have been shown to localise within and cause cell lysis of experimental animal tumors. One of the most important strains in that context is Clostridium. Other bacteria have also been implicated in experimental anti-cancer settings. Of these, attenuated Salmonella strains capable of both selective amplification within tumors and expression of effector genes encoding therapeutic proteins are probably the most promising. We will discuss the potential advantages and the pitfalls of this alternative delivery approach. We will emphasize the importance of hypoxia in solid tumors and discuss the potential of radiation-inducible promoters and combined treatment modalities, involving vascular targeting and radiotherapy. We believe that this approach will act in a complementary way to current radiotherapy and chemotherapy treatments of solid tumors.

Insertion or deletion of the Cheo box modifies radiation inducibility of Clostridium promoters.

Radiation-inducible promoters are being used in many viral vector systems to obtain spatial and temporal control of gene expression. It was previously proven that radiation-induced gene expression can also be obtained in a bacterial vector system using anaerobic apathogenic clostridia. The effect of radiation inducibility was detected using mouse tumor necrosis factor alpha (mTNF-alpha) as a model protein under regulation of the radiation-inducible recA promoter. In this report, experiments are described in which this recA promoter was modified in order to increase radiation responsiveness. Incorporation of an extra Cheo box in the recA promoter region resulted in an increase in mTNF-alpha secretion from 44% for the wild-type promoter to 412% for the promoter with an extra Cheo box after a single irradiation dose of 2 Gy. Deletion of the Cheo box in the promoter region eliminated radiation inducibility. These results prove that the Cheo box in the recA promoter is indeed the radiation-responsive element. We also tested whether we could induce the constitutive endo-beta-1,4-glucanase promoter (eglA) via ionizing irradiation by introducing a Cheo box in the promoter region. While the use of the constitutive promoter did not lead to an increase in mTNF-alpha secretion after irradiation, the introduction of a Cheo box resulted in a 242% increase in mTNF-alpha secretion. Reverse transcriptase PCR of RNA samples isolated from irradiated and nonirradiated bacterial cultures demonstrated that the increase in secretion was the result of enhanced transcription of the mTNF-alpha gene.

Visual categorization of natural and abstract items in forest monkeys and humans.

A preference for novelty paradigm was used to investigate whether mangabeys (Lophocebus albigena), an arboreal non-human primate species, were able to discriminate and to categorize different visual stimuli belonging to natural (food items) and abstract (non-food items) categories. In a comparative perspective human subjects were tested with the same procedure and the same stimuli. Two out of four mangabeys and three out of the four humans showed significant preference for novelty when comparing food versus non-food items. Hence they discriminated between these two sets of items. The two mangabeys and one non-adult human subject sorted the food items in one category, showing no preference for novelty when comparing known and unknown food-items and different views of the same food items. In contrast the two adult human subjects who showed preference for novelty in the between-category, did not show preference for novelty when comparing known and unknown food-items but did show such a preference when comparing different views of the same food items. Compared to human performances, the results suggest that mangabeys are able to form at least a perceptual category of natural, ecologically relevant stimuli.

Severe portal hypertensive gastropathy and antral vascular ectasia are distinct entities in patients with cirrhosis.

BACKGROUND/AIMS: Whereas severe portal hypertensive gastropathy and gastric antral vascular ectasia (GAVE) have been separately defined in patients with cirrhosis, there is much confusion in the literature because they are both characterized by red spots at endoscopy. This prospective study compared clinical, biochemical, and pathological features of these syndromes. METHODS: Three groups of patients with cirrhosis and either GAVE (n = 14), severe portal hypertensive gastropathy (n = 14), or no gastric features at endoscopy (controls; n = 10) were included. RESULTS: No difference was found between patients with gastropathy and controls. Patients with GAVE presented with the following significant differences compared with other patients: a higher Child-Pugh score, a lower blood level of hemoglobin and gastrin, and a higher intestinal blood loss. At pathological examination, these patients more frequently had vascular ectasia (P = 0.04), spindle cell proliferation (P < 0.01), fibrohyalinosis (P = 0.004), and Gilliam's score of > or = 2 (P < 0.05); thrombi were encountered only in patients with GAVE (P = 0.006). Using discriminant analysis, spindle cell proliferation and fibrohyalinosis were the only significant variables yielding a diagnostic accuracy of 85% for GAVE and gastropathy. CONCLUSIONS: GAVE and severe portal hypertensive gastropathy are two distinct entities.