Symbionts protect aphids from parasitic wasps by attenuating herbivore-induced plant volatiles

Plants respond to insect attack by releasing blends of volatile chemicals that attract their herbivores’ specific natural enemies, while insect herbivores may carry endosymbiotic microorganisms that directly improve herbivore survival after natural enemy attack. Here we demonstrate that the two phenomena can be linked. Plants fed upon by pea aphids release volatiles that attract parasitic wasps, and the pea aphid can carry facultative endosymbiotic bacteria that prevent the development of the parasitic wasp larva and thus markedly improve aphid survival after wasp attack. We show that these endosymbionts also attenuate the systemic release of volatiles by plants after aphid attack, reducing parasitic wasp recruitment and increasing aphid fitness. Our results reveal a novel mechanism through which symbionts can benefit their hosts and emphasise the importance of considering the microbiome in understanding insect ecological interactions.

Bacterial symbionts are increasingly known to influence behaviour and fitness in insects. Here, Frago et al. show that plants fed on by aphids with symbionts have altered volatile chemical profiles, leading to reduced parasitoid attack of aphids.

Detection of protozoan and bacterial pathogens of public health importance in faeces of Corvus spp. (large-billed crow)

Parasites and bacteria are reported in the faeces of birds in the current study. Fresh faecal samples of the large-billed crow (Corvus spp.) were collected from the study site at Bangsar, an urban setting in Kuala Lumpur, Malaysia. These samples were transported to laboratory and analysed for parasites and bacteria. Pre-prepared XLD agar plates were used for culturing the bacteria in the laboratory. Using the API 20ETM Test Strips, 9 different species of bacteria were identified belonging to the family Enterobacteriacea. They were Citrobacter freundii, Enterobacter cloacae, Proteus mirabilis, Klebsiella pneumoniae, Kluyvera ascorbata, Salmonella arizonae, Salmonella typhi, Shigella flexneri and Shigella sonnei. The protozoan parasites detected include Cryptosporidium spp., Cyclospora spp., Blastocystis spp., and Capillaria hepatica and Ascaris lumbricoidus ova. Environmental air samples collected on agar plates using an air sampler in the area only produced fungal colonies. Some of these pathogens found in the crows are of zoonotic importance, especially Cryptosporidium, Blastocystis, Cyclopsora, Salmonella, Shigella and Kluyvera. The finding of Kluyvera spp. in crows in our current study highlights its zoonotic potential in an urban setting.

Alpha 2-b interferon and farmarubicin in the prophylaxis of recurrence of superficial transitional cell carcinoma of the urinary bladder

OBJECTIVE

To ascertain the effect of intravesical instillation of Alpha 2-b Interferon (IFN a-2) 10 million I.U. in 50 ml physiological saline as a monotherapy and in combination with Farmarubicin (FRC) 50 mg dissolved together in 50 ml of physiological saline. These substances were administered four times during the first month after TUR-BT and then once monthly for one year either in the form of an IFN a-2 monotherapy or as an IFN a-2 and FRC combination in the therapy of recurrence of transitional cell carcinoma (TCC) of the urinary bladder after transurethral resection of the bladder tumor (TUR-BT). THEORETICAL CONSIDERATION: One of the causes of malignancy is an irreversible shift in the balance between protooncogens and tumor supressorgens. In the genetical process of the control of cell apoptosis, an important role is played by the tumor-supressorgen p 53. By the means of mutation of protooncogenes, cellular oncogenes(C-MYC) are formed, inducing the proliferation of cells of the tumor and via feedback induce also the p53 mutation. By the reduction of cellular oncogenes, IFN a-2 and FRC intervene by blocking the proliferation of tumor cells.

PATIENTS AND METHODS

Authors have checked and treated 33 patients (pts) with recurrent TCC. The first group of 20 pts were after TUR-BT with BCG unsuccessful intravesical therapy, and 13 pts in the second group were with recurrence of TCC, but contraindicated for BCG treatment. These 33 pts (the first and second groups) were compared with 33 pts of the third group after TUR-BT but without intravesical instillation therapy. The pts of the third group did not suffer from any other significant ailment. IFN a-2 monotherapy (10 mill. I.U./or a combination of IFN a-2 + FRC (50 mg/50 ml solution were administered for 2 hours, 1 week after TUR-BT. During the first month, instillations were done weekly, from the second to the twelfth month only once monthly. The results were evaluated for 12 to 33 months (median: 24 months).

RESULTS

Group I: From 20 pts after TUR-BT + unsuccessful BCG + IFN a-2 monotherapy recurrence was registered in 4 pts (20%). Group II: Out of 13 pts after TUR-BT + IFN a-2 + FRC, recurrence was registered in 3 pts (23%). Group I + II: Recurrence in both groups was observed in 7 pts (21.2%). Group III: Out of 33 pts after TUR-BT without immuno- et chemotherapy recurrence was registered in 18 pts (54.5%). After one year of treatment, patients were checked for 24 months. The transition into an invasive tumor was observed in 4 pts (12.1%). In the comparative group of 33 pts without instillation after TUR-BT, recurrence was detected after one year in 18 pts (54.5%) and the transition into an invasive tumor was observed in 7 pts (21.2%).

CONCLUSION

Intravesical instillation of BCG used to be the most frequently applied therapy following TUR-BT. The toxicity of this vaccine as well as the contraindication of this treatment in some diseases, and also the primary or secondary resistance of TCC to BCG have challenged the search for alternative possibilities of the intravesical instillation treatment. IFN a-2 monotherapy and IFN a-2 in combination with FRC are new alternative approaches in the improvement of TCC treatment. This therapy is also supported by research of molecular genetics. (Ref.18.)

[Vaccination by suicide gene therapy against a model of hepatic metastasis from colon cancer in the rat]

Suicide gene therapy consists of transferring into tumor cells a viral or bacterial gene encoding for an enzyme which converts a non-toxic product into a lethal drug.

STUDY AIM

To analyze the therapeutic potential of vaccination with tumor cells expressing the bacterial cytosine deaminase (CD) gene and 5-fluorocytosine (5-FC) treatment in a rat liver metastasis model.

MATERIAL AND METHOD

We used a rat colon carcinoma cell line which, after subcapsular or intraportal injection in syngenic animals, generates single or multiple experimental liver metastases, respectively. We have shown that introduction of a vector expressing the CD gene in this colon carcinoma cell line results in 5-FC sensitivity (PRObCD).

RESULTS

Intrahepatic subcapsular injection of PRObCD tumor cells, followed by 5-FC treatment, induces total regression of a wild-type tumor pre-established in the contralateral liver lobe in 45% of animals with a 96% decrease in mean volume (p < 0.0001), demonstrating the existence of a distant bystander effect. This vaccination significantly increased the survival of rats with single (log-rank p < 0.0001) or multiple (log-rank p = 0.01) liver metastasis

CONCLUSIONS

These results suggest that suicide gene-modified tumor cells can act as potent therapeutic vaccines against liver metastasis from colon carcinoma.

Cytosine deaminase/5-fluorocytosine-based vaccination against liver tumors: evidence of distant bystander effect

BACKGROUND

The cytosine deaminase gene of Escherichia coli converts the nontoxic compound 5-fluorocytosine into 5-fluorouracil (5-FU), thereby acting as a suicide gene when introduced into cancer cells, killing the cells when they are exposed to 5-fluorocytosine. We analyzed the efficacy of using cytosine deaminase-bearing cancer cells as an autologous tumor vaccine in a rat model that mimics liver metastasis from colon carcinoma.

METHODS

We introduced a plasmid vector containing the E. coli cytosine deaminase gene into a BDIX rat colon carcinoma cell line. Intrahepatic injection of the modified cells in syngeneic animals generates a single experimental liver "suicide tumor." We then analyzed the effect of 5-fluorocytosine treatment in terms of regression of cytosine deaminase-expressing cells in vivo as well as protection against wild-type cancer cells.

RESULTS

Treatment with 5-fluorocytosine induced regression of cytosine deaminase-expressing (CD+) tumors, with seven of 11 treated animals being tumor free at the end of 30 days and a statistically significant difference in tumor volumes between treated and control animals (two-sided P<.0001). Intrahepatic injection of CD+ cells followed by 5-fluorocytosine treatment rendered the treated animals resistant to challenge with wild-type tumor cells, with no (zero of seven) treated animals developing wild-type tumors in contrast to all (four of four) control animals. Moreover, in animals with established wild-type liver tumors, injection of CD+ tumor cells followed by 5-fluorocytosine treatment produced a statistically significant increase in survival time (two-sided P<.0001). In vivo immunodepletion and immunohistologic analysis of experimental tumors indicate that natural killer cells are the major immune component involved in this antitumor effect.

CONCLUSIONS AND IMPLICATIONS

Taken together, these results suggest the potential use of suicide gene-modified tumor cells as therapeutic vaccines against liver metastasis from colon carcinoma.