Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities.

BACKGROUND: Plants are hotbeds for parasites such as arthropod herbivores, which acquire nutrients and energy from their hosts in order to grow and reproduce. Hence plants are selected to evolve resistance, which in turn selects for herbivores that can cope with this resistance. To preserve their fitness when attacked by herbivores, plants can employ complex strategies that include reallocation of resources and the production of defensive metabolites and structures. Plant defences can be either prefabricated or be produced only upon attack. Those that are ready-made are referred to as constitutive defences. Some constitutive defences are operational at any time while others require activation. Defences produced only when herbivores are present are referred to as induced defences. These can be established via de novo biosynthesis of defensive substances or via modifications of prefabricated substances and consequently these are active only when needed. Inducibility of defence may serve to save energy and to prevent self-intoxication but also implies that there is a delay in these defences becoming operational. Induced defences can be characterized by alterations in plant morphology and molecular chemistry and are associated with a decrease in herbivore performance. These alterations are set in motion by signals generated by herbivores. Finally, a subset of induced metabolites are released into the air as volatiles and function as a beacon for foraging natural enemies searching for prey, and this is referred to as induced indirect defence. SCOPE: The objective of this review is to evaluate (1) which strategies plants have evolved to cope with herbivores and (2) which traits herbivores have evolved that enable them to counter these defences. The primary focus is on the induction and suppression of plant defences and the review outlines how the palette of traits that determine induction/suppression of, and resistance/susceptibility of herbivores to, plant defences can give rise to exploitative competition and facilitation within ecological communities "inhabiting" a plant. CONCLUSIONS: Herbivores have evolved diverse strategies, which are not mutually exclusive, to decrease the negative effects of plant defences in order to maximize the conversion of plant material into offspring. Numerous adaptations have been found in herbivores, enabling them to dismantle or bypass defensive barriers, to avoid tissues with relatively high levels of defensive chemicals or to metabolize these chemicals once ingested. In addition, some herbivores interfere with the onset or completion of induced plant defences, resulting in the plant's resistance being partly or fully suppressed. The ability to suppress induced plant defences appears to occur across plant parasites from different kingdoms, including herbivorous arthropods, and there is remarkable diversity in suppression mechanisms. Suppression may strongly affect the structure of the food web, because the ability to suppress the activation of defences of a communal host may facilitate competitors, whereas the ability of a herbivore to cope with activated plant defences will not. Further characterization of the mechanisms and traits that give rise to suppression of plant defences will enable us to determine their role in shaping direct and indirect interactions in food webs and the extent to which these determine the coexistence and persistence of species.

Testing for reproductive interference in the population dynamics of two congeneric species of herbivorous mites.

When phylogenetically close, two competing species may reproductively interfere, and thereby affect their population dynamics. We tested for reproductive interference (RI) between two congeneric haplo-diploid spider mites, Tetranychus evansi and Tetranychus urticae, by investigating their interspecific mating and their population dynamics when they competed on the same plants. They are both pests of tomato, but differ in the host plant defences that they suppress or induce. To reduce the effect of plant-mediated interaction, we used a mutant tomato plant lacking jasmonate-mediated anti-herbivore defences in the competition experiment. In addition, to manipulate the effect of RI, we introduced founder females already mated with conspecific males in mild RI treatments or founder, virgin females in strong RI treatments (in either case together with heterospecific and conspecific males). As females show first-male sperm precedence, RI should occur especially in the founder generation under strong RI treatments. We found that T. urticae outcompeted T. evansi in mild, but not in strong RI treatments. Thus, T. evansi interfered reproductively with T. urticae. This result was supported by crossing experiments showing frequent interspecific copulations, strong postmating reproductive isolation and a preference of T. evansi males to mate with T. urticae (instead of conspecific) females, whereas T. urticae males preferred conspecific females. We conclude that interspecific mating comes at a cost due to asymmetric mate preferences of males. Because RI by T. evansi can improve its competitiveness to T. urticae, we propose that RI partly explains why T. evansi became invasive in Europe where T. urticae is endemic.

Herbivory-associated degradation of tomato trichomes and its impact on biological control of Aculops lycopersici.

Tomato plants have their leaves, petioles and stems covered with glandular trichomes that protect the plant against two-spotted spider mites and many other herbivorous arthropods, but also hinder searching by phytoseiid mites and other natural enemies of these herbivores. This trichome cover creates competitor-free and enemy-free space for the tomato russet mite (TRM) Aculops lycopersici (Acari: Eriophyidae), being so minute that it can seek refuge and feed inbetween the glandular trichomes on tomato cultivars currently used in practice. Indeed, several species of predatory mites tested for biological control of TRM have been reported to feed and reproduce when offered TRM as prey in laboratory experiments, yet in practice these predator species appeared to be unable to prevent TRM outbreaks. Using the phytoseiid mite, Amblydromalus limonicus, we found exactly the same, but also obtained evidence for successful establishment of a population of this predatory mite on whole plants that had been previously infested with TRM. This successful establishment may be explained by our observation that the defensive barrier of glandular plant trichomes is literally dropped some time after TRM infestation of the tomato plants: the glandular trichome heads first rapidly develop a brownish discoloration after which they dry out and fall over onto the plant surface. Wherever TRM triggered this response, predatory mites were able to successfully establish a population. Nevertheless, biological control was still unsuccessful because trichome deterioration in TRM-infested areas takes a couple of days to take effect and because it is not a systemic response in the plant, thereby enabling TRM to seek temporary refuge from predation in pest-free trichome-dense areas which continue to be formed while the plant grows. We formulate a hypothesis unifying these observations into one framework with an explicit set of assumptions and predictions to be tested in future experiments.

Risk factors for in-hospital mortality following hip fracture. / Factores de riesgo de mortalidad intrahospitalaria en la fractura proximal de fémur.

OBJECTIVE: To identify and quantify the risk factors for in-hospital mortality in patients older than 65 years with a hip fracture. MATERIALS AND METHODS: Retrospective review of prospectively collected data. We studied a cohort of 331 hip fracture patients older than 65 years of age admitted to our hospital from 2011 to 2014. Patients demographics, type of residence, physical function, mobility, prefracture comorbidities data, cognitive status, anti-aggregant and anticoagulant medication, preoperative haemoglobin value, type of fracture, type of treatment, surgical delay, and complications, were recorded. RESULTS: The average age was 83, 73% female, and 57% had sustained a subcapital fracture. In 62.8% pre-fracture baseline co-morbidities were equal or greater than 2. The in-hospital mortality rate was 11.4%. In univariate analysis, age over 90, male gender, haemoglobin ≤ 10g/dl, no antiplatelet agents, orthopaedic treatment, number of co-morbidities≥2, Charlson index≥2, age-adjusted Charlson index≥6, congestive heart failure, asthma, rheumatologic disease, were associated with in-hospital mortality. CONCLUSIONS: Preoperative patient-related factors have a strong relationship with in-hospital mortality in a hip fracture patients aged older than 65 years. These factors are non-modifiable; we recommend the development of protocols to reduce in-hospital mortality in this group of patients.

Spread of a new Chlamydia trachomatis variant from men who have sex with men to the heterosexual population after replacement and recombination in ompA and pmpH genes.

OBJECTIVES: Sexually transmitted infections are frequently related to outbreaks in high-risk populations due to the dense sexual networks. We wanted to determine the dissemination of a Chlamydia trachomatis variant characterized by the pmpH-recombinant gene between L and G genotypes, which was previously described in a high-risk population. METHODS: A total of 449 samples were analysed in two periods ranging from 2009 to 2015 for detection of the pmpH-recombinant gene. For those samples yielding positive amplification, a sampling was selected for phylogenetic reconstructions based on sequencing of five chromosomal genes. RESULTS: Globally this variant was found in 113 of the 449 samples (25%). During the first years (2009-13), this variant was found almost exclusively in rectal samples (30/112 samples) of men who have sex with men and in only one non-rectal sample (1/63). In 2014, this variant was also found in urethral and pharyngeal samples (1/24 and 1/7, respectively). However, in 2015, an epidemiological change was observed as the proportion of this variant had increased in rectal samples (20/51; 39%) and non-rectal samples, including cervical samples (51/142; 36.4%). The molecular characterization revealed the replacement of the ompA gene belonging to subtype G in samples recovered from 2009 to 2013 by the ompA gene belonging to subtype J after 2013. CONCLUSIONS: Our data would support the evidence that subtype J could be a 'subtype bridge' between different sexual networks, as subtype J has been found in men who have sex with men and heterosexual populations in similar proportions. This work reveals the necessity of implementing molecular surveillance in extra-rectal samples to help us understand the gaps in transmission.

Extra-adrenal myelolipomas compared with extramedullary hematopoietic tumors: a case of presacral myelolipoma.

A large presacral myelolipoma associated with increasing constipation is reported in a 70-year-old obese diabetic female. The resected tumor was encapsulated and dark red to yellow. Light and electron microscopy revealed mature and immature hematopoietic tissue, lymphoid aggregates and mature adipocytes. Myelolipomas arising in extra-adrenal sites are rare. Considered in the differential diagnosis are reactive extramedullary hematopoietic tumors that usually occur in patients with severe chronic anemias. Patients with extramedullary hematopoietic tumors are characterized by anemia, frequent hepatosplenomegaly and abnormal peripheral blood smears, and may be any age. The tumors are usually multiple and usually located in the mediastinum or epidural space. In contrast, patients with extra-adrenal myelolipomas are usually older than 40 years, have normal blood studies, absent hepatosplenomegaly, and usually have chronic debilitating diseases or endocrinopathies. Extra-adrenal myelolipomas are single and usually occur within the abdomen. Extramedullary hematopoietic tumors have a predominance of the hematopoietic component, with erythroid hyperplasia of that component. Extra-adrenal myelolipomas may have a predominance of either the hematopoietic or fatty component, chiefly the latter, and generally have a more conspicuous lymphocyte population. Although the components of these tumors are the same, we consider them separable clinically, pathogenetically and, in many cases, pathologically.

Multicentric reference values for some quantities measured with the Elecsys 2010 analyser.

Several clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for quantities concerning thyrotropin, non-protein bound thyroxine, triiodothyronine, cobalamines and folates, using an Elecsys 2010 analyser. All the logistic work has been done in co-operation with the supplier of the analyser (Roche Diagnostics España, S.L., Barcelona). The reference limits produced in the virtual laboratory are in fact derived from the blend of reference values obtained by each laboratory. The multicentric reference limits were estimated according to the recommendations of the International Federation of Clinical Chemistry. The work done represents a model of co-operation between the in vitro diagnostic industry and clinical laboratories for the production of reference values.

[Aortic prosthetic endocarditis and periprosthetic abscess caused by Staphylococcus aureus]. / Endocarditis protésica aórtica y absceso periprotesico por Staphylococcus aureus.

Prosthetic endocarditis with annular abscess formation is a severe complication of cardiac valve replacement fortunately uncommon, though highly lethal. Increasing surgical experience and the high mortality with medical management have led to a widespread recommendation for early prosthetic replacement. We report a case of a 49 year old man with infective endocarditis due to Staphylococcus aureus in aortic ascendens prosthetic and aortic valve prosthetic complicated with periaortic abscess which was as successful treatment by drain of abscess without prosthetic replacement.

Clinical and epidemiological characterization of a lymphogranuloma venereum outbreak in Madrid, Spain: co-circulation of two variants.

The lymphogranuloma venereum (LGV) outbreak described in the Netherlands in 2003, increased the interest in the genotyping of Chlamydia trachomatis. Although international surveillance programmes were implemented, these studies slowly decreased in the following years. Now data have revealed a new accumulation of LGV cases in those European countries with extended surveillance programmes. Between March 2009 and November 2011, a study was carried out to detect LGV cases in Madrid. The study was based on screening of C. trachomatis using commercial kits, followed by real-time pmpH-PCR discriminating LGV strains, and finally ompA gene was sequenced for phylogenetic reconstruction. Ninety-four LGV infections were identified. The number of cases increased from 10 to 30 and then to 54 during 2009-2011. Incidence of LGV was strongly associated with men who have sex with men; but in 2011, LGV cases were described in women and heterosexual men. Sixty-nine patients were also human immunodeficiency virus (HIV) positive, with detectable viral loads at the moment of LGV diagnosis, suggesting a high-risk of co-transmission. In fact, in four patients the diagnosis of HIV was simultaneous with LGV infection. The conventional treatment with doxycycline was prescribed in 75 patients, although in three patients the treatment failed. The sequencing of the ompA gene permitted identification of two independent transmission nodes. One constituted by 25 sequences identical to the L2b variant, and a second node including 37 sequences identical to L2. This epidemiological situation characterized by the co-circulation of two LGV variants has not been previously described, reinforcing the need for screening and genotyping of LGV strains.

Annual rhythmic and non-rhythmic biological variation of magnesium and ionized calcium concentrations.

The annual inter- and intra-individual biological variation, including the circannual rhythmic variation, of the serum concentrations of magnesium and ionized calcium has been investigated in a group of 51 apparently healthy volunteers. Venous blood specimens were collected on intervals of once a month within a one-year period, using a standardized protocol. The inter-individual coefficients of variation were 5.12% for magnesium and 1.58% for ionized calcium. The medians of the intra-individual coefficients of variation were 1.93% for magnesium and 2.18% for ionized calcium. These data were used to determine the allowable imprecision, the allowable systematic error, the critical difference for significant change detection, and the usefulness of population reference values (index of individuality). Of the quantities studied, only the serum concentration of ionized calcium shows a significant annual rhythmic variation (amplitude 1.3%), although this result may be due to the between-run metrological variance, considering that the concentration of ionized calcium of the control material used during the study possesses a similar significant rhythmic variation.

Multicentric reference values for some quantities measured with Tina-Quant reagents systems and RD/Hitachi analysers.

Ten clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for quantities concerning ferritin, transferrin, rheumatoid factors, C-reactive protein and antistreptolysin O, using Tina-Quant reagents systems and RD/Hitachi analysers. All the logistic work has been done in co-operation with the supplier of the reagents and analysers (Roche Diagnostics España, S.L., Barcelona). The reference limits produced in the virtual laboratory are derived from the blend of reference values obtained by each laboratory. The multicentric reference limits were estimated according to the recommendations of the International Federation of Clinical Chemistry. The work done is a model of co-operation between the in vitro diagnostic industry and clinical laboratories for the production of reference values.