Serial horizontal transfer of vitamin-biosynthetic genes enables the establishment of new nutritional symbionts in aphids’ di-symbiotic systems

Abstract Many insects depend on obligate mutualistic bacteria to provide essential nutrients lacking from their diet. Most aphids, whose diet consists of phloem, rely on the bacterial endosymbiont Buchnera aphidicola to supply essential amino acids and B vitamins. However, in some aphid species, provision of these nutrients is partitioned between Buchnera and a younger bacterial partner, whose identity varies across aphid lineages. Little is known about the origin and the evolutionary stability of these di-symbiotic systems. It is also unclear whether the novel symbionts merely compensate for losses in Buchnera or carry new nutritional functions. Using whole-genome endosymbiont sequences of nine Cinara aphids that harbour an Erwinia-related symbiont to complement Buchnera, we show that the Erwinia association arose from a single event of symbiont lifestyle shift, from a free-living to an obligate intracellular one. This event resulted in drastic genome reduction, long-term genome stasis, and co-divergence with aphids. Fluorescence in situ hybridisation reveals that Erwinia inhabits its own bacteriocytes near Buchnera’s. Altogether these results depict a scenario for the establishment of Erwinia as an obligate symbiont that mirrors Buchnera’s. Additionally, we found that the Erwinia vitamin-biosynthetic genes not only compensate for Buchnera’s deficiencies, but also provide a new nutritional function; whose genes have been horizontally acquired from a Sodalis-related bacterium. A subset of these genes have been subsequently transferred to a new Hamiltonella co-obligate symbiont in one specific Cinara lineage. These results show that the establishment and dynamics of multi-partner endosymbioses can be mediated by lateral gene transfers between co-ocurring symbionts.

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Serial horizontal transfer of vitamin-biosynthetic genes enables the establishment of new nutritional symbionts in aphids’ di-symbiotic systems

10.1101/556274 ◽

2019 ◽

Author(s):

Alejandro Manzano-Marín ◽

Armelle Coeur d’acier ◽

Anne-Laure Clamens ◽

Céline Orvain ◽

Corinne Cruaud ◽

...

Keyword(s):

Essential Amino Acids ◽

B Vitamins ◽

Restricted Diet ◽

Symbiotic System ◽

Biosynthetic Genes ◽

Obligate Symbiont ◽

Related Bacterium ◽

B Vitamin

ABSTRACTMany insects with a nutrient-restricted diet depend on obligate mutualistic bacteria for the provisioning of essential nutrients lacking from their food source, namely essential amino acids and B vitamins. Most aphids (Hemiptera: Aphididae), whose diet consists of phloem, rely on the bacterial endosymbiont Buchnera for the supply of the aforementioned compounds. However, in some aphid lineages Buchnera have lost the capability of producing these nutrients and thus the symbiotic consortium has accommodated an extra bacterial partner to supplement Buchnera’s deficiencies. In this work, we explore the di-symbiotic nutritional endosymbiosis of a group of Cinara aphids which has been found to harbour both Buchnera and an Erwinia-related symbiont. Using fluorescence in situ hybridisation, we have located this symbiont to the bacteriome where it inhabits its own bacteriocytes. Through whole-genome sequencing of the endosymbionts of 9 species of Erwinia-associated Cinara aphids, we have found that Ewrinia genomes are highly syntenic and all show significant genome reduction. Additionally, Erwinia symbionts display phylogenetic congruency with Buchnera, suggesting long-term co-divergence. Most significantly, we found that not only is Erwinia capable of complementing Buchnera’s auxotrophies, but that the genes involved in the biosynthesis of two B vitamins have actually been horizontally acquired from a Sodalis-related bacterium. Finally, this B-vitamin biosynthetic genes have been further transferred to a new Hamiltonella co-obligate symbiont in a specific Cinara lineage, thus displaying a tri-symbiotic system. These results highlight the important role horizontal gene transfer plays in the establishment of new obligate nutritional symbionts.

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Relevance of a medicosurgical strategy combining cetuximab and chronomodulated (Chrono) chemotherapy (chemo) with metastases resection as 3rd line treatment for patients (pts) with metastatic colorectal cancer (MCRC)

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.14505 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 14505-14505

Author(s):

A. Karaboue ◽

M. Bouchahda ◽

R. Adam ◽

P. Innominato ◽

M. P. Bralet ◽

...

Keyword(s):

Objective Response ◽

In Situ Hybridisation ◽

Progression Free Survival ◽

Fluorescence In Situ Hybridisation ◽

Term Survival ◽

Survival Estimate ◽

Gene Copies ◽

Acneiform Rash

14505 Background: Metastases surgery offers long tem survival for pts with chemo-downstaged MCRC (Adam et al. Ann Surg 2004). The relevance of this medicosurgical strategy was investigated in pts given cetuximab (Cetux) and Chrono after chemo failure. Methods: 56 pts with progressive MCRC on prior chemo received Cetux (400 mg/m2 on 1st dose then 250 mg/m2/week) and q2w Chrono based on irinotecan (34 pts), oxaliplatin (14 pts) or both (8 pts). Toxicity grades (G) and response were assessed q2w and q8w, respectively. Tumour EGFR was determined by immunohistochemistry (all pts) and gene copies by fluorescence in situ hybridisation (27 pts). Metastases surgery was attempted whenever complete resection was foreseen. Results: Median of 3 prior chemo (1 to 8); median age: 61 years (35 to 79); M/F: 34/22; WHO PS 0/1/2/3: 37/14/4/1; colon/rectum: 32/24; M sites 1/2/=3: 15/22/19; liver/lung: 45/40. EGFR was detected in the tumor of 39 pts (69.6%). 3 pts had G4 allergy. 53 evaluable pts received a median of 5 courses of Cetux-Chrono (1–22). G2–3 acneiform rash occurred in 36 pts (67.8%; G3: 30.4%). Main G3–4 toxicities were diarrhea (26.5%), neutropenia (23.1%) and neuropathy (22.6%). The objective response rate (ORR) was 32% [95% CI, 19.4 to 44.6] (13 PR and 3 CR). ORR was correlated positively with acneiform rash (p= 0.019) but negatively with the detection of EGFR+ tumor cells (0%, ORR=54.5%; 1–10%, 33%; >10%, 16.7%; p = 0.044). No EGFR amplification was documented including 8 OR. Median progression-free survival (PFS) and overall survival were 5.1 [3.2–6.9] and 13.9 months [6.5–21.3] respectively. Metastases surgery was performed in 10 pts (8 R0, 2 R1) after 3–15 courses of Cetux-Chrono as 2nd-5th line. Median PFS in resected pts was 11.7 months [5.8–17.6], with a survival estimate of 80% at 21 months. Conclusions: Cetux-Chrono safely reverted MCRC resistance and allowed successful metastases resection in 17.8% of these pts, like 1st line chemo. This medicosurgical strategy impacted favourably on long term survival, despite its application as 3rd treatment line. Supported by ARTBC, Hôpital Paul Brousse, Villejuif, France No significant financial relationships to disclose.

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Rapid Multi-Hybridisation FISH Screening for Balanced Porcine Reciprocal Translocations Suggests a Much Higher Abnormality Rate Than Previously Appreciated

Cells ◽

10.3390/cells10020250 ◽

2021 ◽

Vol 10 (2) ◽

pp. 250

Author(s):

Rebecca E O’Connor ◽

Lucas G Kiazim ◽

Claudia C Rathje ◽

Rebecca L Jennings ◽

Darren K Griffin

Keyword(s):

Semen Analysis ◽

In Situ Hybridisation ◽

Economic Loss ◽

Environmental Damage ◽

Fluorescence In Situ Hybridisation ◽

Reciprocal Translocations ◽

Chromosome Translocations ◽

Farrowing Rate ◽

Significant Economic Loss

With demand rising, pigs are the world’s leading source of meat protein; however significant economic loss and environmental damage can be incurred if boars used for artificial insemination (AI) are hypoprolific (sub-fertile). Growing evidence suggests that semen analysis is an unreliable tool for diagnosing hypoprolificacy, with litter size and farrowing rate being more applicable. Once such data are available, however, any affected boar will have been in service for some time, with significant financial and environmental losses incurred. Reciprocal translocations (RTs) are the leading cause of porcine hypoprolificacy, reportedly present in 0.47% of AI boars. Traditional standard karyotyping, however, relies on animal specific expertise and does not detect more subtle (cryptic) translocations. Previously, we reported development of a multiple hybridisation fluorescence in situ hybridisation (FISH) strategy; here, we report on its use in 1641 AI boars. A total of 15 different RTs were identified in 69 boars, with four further animals XX/XY chimeric. Therefore, 4.5% had a chromosome abnormality (4.2% with an RT), a 0.88% incidence. Revisiting cases with both karyotype and FISH information, we reanalysed captured images, asking whether the translocation was detectable by karyotyping alone. The results suggest that chromosome translocations in boars may be significantly under-reported, thereby highlighting the need for pre-emptive screening by this method before a boar enters a breeding programme.

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