Discovery of an Insect Neuroactive Helix Ring Peptide from Ant Venom

Ants are among the most abundant terrestrial invertebrate predators on Earth. To overwhelm their prey, they employ several remarkable behavioral, physiological, and biochemical innovations, including an effective paralytic venom. Ant venoms are thus cocktails of toxins finely tuned to disrupt the physiological systems of insect prey. They have received little attention yet hold great promise for the discovery of novel insecticidal molecules. To identify insect-neurotoxins from ant venoms, we screened the paralytic activity on blowflies of nine synthetic peptides previously characterized in the venom of Tetramorium bicarinatum. We selected peptide U11, a 34-amino acid peptide, for further insecticidal, structural, and pharmacological experiments. Insecticidal assays revealed that U11 is one of the most paralytic peptides ever reported from ant venoms against blowflies and is also capable of paralyzing honeybees. An NMR spectroscopy of U11 uncovered a unique scaffold, featuring a compact triangular ring helix structure stabilized by a single disulfide bond. Pharmacological assays using Drosophila S2 cells demonstrated that U11 is not cytotoxic, but suggest that it may modulate potassium conductance, which structural data seem to corroborate and will be confirmed in a future extended pharmacological investigation. The results described in this paper demonstrate that ant venom is a promising reservoir for the discovery of neuroactive insecticidal peptides.

Bacteriocyte plasticity in pea aphids facing amino acid stress or starvation during development

An important contributing factor to the evolutionary success of insects is nutritional association with microbial symbionts, which provide the host insects with nutrients lacking in their unbalanced diets. These symbionts are often compartmentalized in specialized cells of the host, the bacteriocytes. Even though bacteriocytes were first described more than a century ago, few studies have explored their dynamics throughout the insect life cycle and in response to environmental stressors. Here, we use the Buchnera aphidicola/pea aphid symbiotic system to study how bacteriocytes are regulated in response to nutritional stress throughout aphid development. Using artificial diets, we analyzed the effects of depletion or excess of phenylalanine or leucine, two amino acids essential for aphid growth and whose biosynthetic pathways are shared between the host and the symbiont. Bacteriocytes responded dynamically to those treatments, while other tissues showed no obvious morphological change. Amino acid depletion resulted in an increase in bacteriocyte numbers, with the extent of the increase depending on the amino acid, while excess either caused a decrease (for leucine) or an increase (for phenylalanine). Only a limited impact on survival and fecundity was observed, suggesting that the adjustment in bacteriocyte (and symbiont) numbers is sufficient to withstand these nutritional challenges. We also studied the impact of more extreme conditions by exposing aphids to a 24 h starvation period at the beginning of nymphal development. This led to a dramatic drop in aphid survival and fecundity and a significant developmental delay. Again, bacteriocytes responded dynamically, with a considerable decrease in number and size, correlated with a decrease in the number of symbionts, which were prematurely degraded by the lysosomal system. This study shows how bacteriocyte dynamics is integrated in the physiology of insects and highlights the high plasticity of these cells.

Aphid BCR4 Structure and Activity Uncover a New Defensin Peptide Superfamily

Aphids (Hemiptera: Aphidoidea) are among the most detrimental insects for agricultural plants, and their management is a great challenge in agronomical research. A new class of proteins, called Bacteriocyte-specific Cysteine-Rich (BCR) peptides, provides an alternative to chemical insecticides for pest control. BCRs were initially identified in the pea aphid Acyrthosiphon pisum. They are small disulfide bond-rich proteins expressed exclusively in aphid bacteriocytes, the insect cells that host intracellular symbiotic bacteria. Here, we show that one of the A. pisum BCRs, BCR4, displays prominent insecticidal activity against the pea aphid, impairing insect survival and nymphal growth, providing evidence for its potential use as a new biopesticide. Our comparative genomics and phylogenetic analyses indicate that BCRs are restricted to the aphid lineage. The 3D structure of BCR4 reveals that this peptide belongs to an as-yet-unknown structural class of peptides and defines a new superfamily of defensins.

The Di-Symbiotic Systems in the Aphids Sipha maydis and Periphyllus lyropictus Provide a Contrasting Picture of Recent Co-Obligate Nutritional Endosymbiosis in Aphids

Dependence on multiple nutritional bacterial symbionts forming a metabolic unit has repeatedly evolved in many insect species that feed on nutritionally unbalanced diets such as plant sap. This is the case for aphids of the subfamilies Lachninae and Chaitophorinae, which have evolved di-symbiotic systems in which the ancient obligate nutritional symbiont Buchnera aphidicola is metabolically complemented by an additional nutritional symbiont acquired more recently. Deciphering how different symbionts integrate both metabolically and anatomically in such systems is crucial to understanding how complex nutritional symbiotic systems function and evolve. In this study, we sequenced and analyzed the genomes of the symbionts B. aphidicola and Serratia symbiotica associated with the Chaitophorinae aphids Sipha maydis and Periphyllus lyropictus. Our results show that, in these two species, B. aphidicola and S. symbiotica complement each other metabolically (and their hosts) for the biosynthesis of essential amino acids and vitamins, but with distinct metabolic reactions supported by each symbiont depending on the host species. Furthermore, the S. symbiotica symbiont associated with S. maydis appears to be strictly compartmentalized into the specialized host cells housing symbionts in aphids, the bacteriocytes, whereas the S. symbiotica symbiont associated with P. lyropictus exhibits a highly invasive phenotype, presumably because it is capable of expressing a larger set of virulence factors, including a complete flagellum for bacterial motility. Such contrasting levels of metabolic and anatomical integration for two S. symbiotica symbionts that were recently acquired as nutritional co-obligate partners reflect distinct coevolutionary processes specific to each association.

Compartmentalized into Bacteriocytes but Highly Invasive: the Puzzling Case of the Co-Obligate Symbiont Serratia symbiotica in the Aphid Periphyllus lyropictus

Dependence on multiple nutritional symbionts that form a metabolic unit has evolved many times in insects. Although it has been postulated that host dependence on these metabolically interconnected symbionts is sustained by their high degree of anatomical integration (these symbionts are often housed in distinct symbiotic cells, the bacteriocytes, assembled into a common symbiotic organ, the bacteriome), the developmental aspects of such multipartner systems have received little attention. Aphids of the subfamilies Chaitophorinae and Lachninae typically harbor disymbiotic systems in which the metabolic capabilities of the ancient obligate symbiont Buchnera aphidicola are complemented by those of a more recently acquired nutritional symbiont, often belonging to the species Serratia symbiotica. Here, we used microscopy approaches to finely characterize the tissue tropism and infection dynamics of the disymbiotic system formed by B. aphidicola and S. symbiotica in the Norway maple aphid Periphyllus lyropictus (Chaitophorinae). Our observations show that, in this aphid, the co-obligate symbiont S. symbiotica exhibits a dual lifestyle: intracellular by being housed in large syncytial bacteriocytes embedded between B. aphidicola-containing bacteriocytes in a well-organized compartmentalization pattern, and extracellular by massively invading the digestive tract and other tissues during embryogenesis. This is the first reported case of an obligate aphid symbiont that is internalized in bacteriocytes but simultaneously adopts an extracellular lifestyle. This unusual infection pattern for an obligate insect symbiont suggests that some bacteriocyte-associated obligate symbionts, despite their integration into a cooperative partnership, still exhibit invasive behavior and escape strict compartmentalization in bacteriocytes. IMPORTANCE Multipartner nutritional endosymbioses have evolved many times in insects. In Chaitophorinae aphids, the eroded metabolic capabilities of the ancient obligate symbiont B. aphidicola are complemented by those of more recently acquired symbionts. Here, we report the atypical case of the co-obligate S. symbiotica symbiont associated with P. lyropictus. This bacterium is compartmentalized into bacteriocytes nested into the ones harboring the more ancient symbiont B. aphidicola, reflecting metabolic convergences between the two symbionts. At the same time, S. symbiotica exhibits highly invasive behavior by colonizing various host tissues, including the digestive tract during embryogenesis. The discovery of this unusual phenotype for a co-obligate symbiont reveals a new face of multipartner nutritional endosymbiosis in insects. In particular, it shows that co-obligate symbionts can retain highly invasive traits and suggests that host dependence on these bacterial partners may evolve prior to their strict compartmentalization into specialized host structures.

The genome sequence of the grape phylloxera provides insights into the evolution, adaptation, and invasion routes of an iconic pest

BACKGROUND

Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture.

RESULTS

Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved > 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world.

CONCLUSIONS

The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture.

Procalcitonin does discriminate between sepsis and systemic inflammatory response syndrome

AIMS

To evaluate whether procalcitonin (PCT) and C reactive protein (CRP) are able to discriminate between sepsis and systemic inflammatory response syndrome (SIRS) in critically ill children.

METHODS

Prospective, observational study in a paediatric intensive care unit. Kinetics of PCT and CRP were studied in patients undergoing open heart surgery with cardiopulmonary bypass (CPB) (SIRS model; group I1) and patients with confirmed bacterial sepsis (group II).

RESULTS

In group I, PCT median concentration was 0.24 ng/ml (reference value <2.0 ng/ml). There was an increment of PCT concentrations which peaked immediately after CPB (median 0.58 ng/ml), then decreased to 0.47 ng/ml at 24 h; 0.33 ng/ml at 48 h, and 0.22 ng/ml at 72 h. CRP median concentrations remained high on POD1 (36.6 mg/l) and POD2 (13.0 mg/l). In group II, PCT concentrations were high at admission (median 9.15 ng/ml) and subsequently decreased in 11/14 patients who progressed favourably (median 0.31 ng/ml). CRP levels were high in only 11/14 patients at admission. CRP remained high in 13/14 patients at 24 h; in 12/14 at 48 h; and in 10/14 patients at 72 h. Median values were 95.0, 50.9, 86.0, and 20.3 mg/l, respectively. The area under the ROC curve was 0.99 for PCT and 0.54 for CRP. Cut off concentrations to differentiate SIRS from sepsis were >2 ng/ml for PCT and >79 mg/l for CRP.

CONCLUSION

PCT is able to differentiate between SIRS and sepsis while CRP is not. Moreover, unlike CRP, PCT concentrations varied with the evolution of sepsis.

[Algal flora of Lake Amapá in Rio Branco, Acre State, II: chlorophyta]

In this study, 15 samples were collected on a bi-monthly basis, during the period between March and May 1994, and 3 additional samples were collected, one in each of the months of July, October and November 1994. All the samples were collected in Lake Amapá (lat. 10 degrees 2'36"S, long. 67 degrees 50'24"W), which is located in Rio Branco, Acre State, Brazil. Ten táxons, of Chlorophyta were registered: Botryococcaceae (2), Treubariaceae (1), Volvocaceae (2), Closteriaceae (3) e Desmidiaceae (2). All taxa identified are first citations for Acre State.

[The Medico-Social Cardiology Center of Coimbra. History and epilogue]

The Medico-Social Cardiology Center of Coimbra, designed and founded by João Porto in 1941, played a remarkable (and pioneering) role in helping cardiac patients in the central part of Portugal. Its work was made possible by the commitment of many doctors, nurses and Social Center Bulletins. For a quarter of a century the number of medical and social interventions in favor of cardiac patients is truly remarkable. Meanwhile, improvements in the national social services--easier access to medical services, free semiology exams, subsidized drugs, state illness subsidies--caused a reduction of monetary contributions from both partners and wealthier and healthier cardiac patients. Little by little the Center's activity was reduced, which ultimately led to its recent dissolution. The Center's books were placed in the Archive of the University and its assets (bank deposits) were donated to the Association for the Development of Cardiology at the University Hospital in Coimbra. As its name suggests, the main goal of this non-profit association consists in the promotion of scientific and technological improvement of the Cardiology Department at the University Hospital of Coimbra.

[The outlook for medical ethics in the 1990s]

The evolution of medicine throughout time--in clinical practice, in scientific progress and in the development of new technologies of semeiology and therapeutics-, created a long list of ethical problems unknown before. If the Hippocratic oath remains valid nowadays, as a true monument of rare moral elegance, the truth is, that it began to be unable to cover all the new aspects created by the evolution of Medicine on one hand, and the transformation of the Society, on the other hand. Therefore, the confrontation of the traditional principles of Medical ethics with the new realities is mandatory, to analyse a long list of well defined questions such as, clinical trials, human experimentation, problems related with the creation of life and its ending, organ transplants molecular biology, medical genetics, analysis of, human genome and its consequences, new biotechnologies, as well as other questions that are covered by the broader aspect of bioethics, interlinking in this way several areas of knowledge. All the technologies used in clinical practice, radically changed the traditional relation between the doctor and the patient, and created not only a number of new problems, but also, clear threats to medical secrecy and patient privacy. The exponential increase in the number of terminal patients made for way some temptations (intensive care, euthanasia) and for the idea of developing a correct structure palliative Medicine.(ABSTRACT TRUNCATED AT 250 WORDS)

[Primary heart tumors. Report of a clinical case]

The authors describe the case of a 52-year-old patient with several hospitalizations due to acute pulmonary edema, clarified only during the performance of cardiac surgery for the correction of presumable mitral valvular pathology. A leiomiossarcome of the left auricle was concerned, which involved the posterior ring of the mitral valve, the interauricular septum and the orifices of the pulmonary veins. Due to the impossibility of proceeding with the complete resection of the tumor, the tumoral mass was wasted away in order to liberate the involved structures, this followed by chemotherapy. Two years since, the patient shows a generally deteriorated state, submitted to various hospitalizations due to cardiac insufficiency, having been objectivated hepatic metastization and recurrence of the primary neoplasm.

[Immunization with an anti-Lewis a antibody]

A case of immunological sensitization for a natural and irregular anti-Lewis a antibody, is presented. Immuno-hematologic studies of blood and saliva, and identification of seric antibody through a panel of phenotype red cells, were made.

[The development of cardiology in the last 40 years]

In order to correctly appreciate the way cardiology developed in the last 40 years, the "state-of-the-art" balance when the first World Congress took place, September-1950, in Paris, is made. The most current diagnostic methods were relatively scarce at the time-ECG, chest X ray, phonocardiography, pulse wave tracings, coupled with vectorcardiography and ballistocardiography, but in the well equipped hospitals right ventricular catheterization was already performed. The therapeutics of the important morbid situations-like congestive heart failure, arterial hypertension, myocardial infarction and ischemia was disappointing, but closed heart surgery was already taking place. Since then, things had changed suddenly. Over the last 40 years a marked scientific and technology explosion has emerged, that had benefited cardiology science, encompassing several broad areas, namely, patient approaching, pathophysiology understanding, the emergence of new drugs and clinical use, interventional cardiology and remarkable progress in open heart surgery. Imaging techniques development and other technology lead to a simple and accurate cardiac diagnosis. 24 hours ECG and blood pressure recording, and cardiac output measurement, greatly improves our medical knowledge. Computers development, representing the most significant technology advances, has given to cardiology non-predicted advances.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diabetes mellitus and coronopathy]

Diabetes Mellitus represents an important public health problem in the most developed industrialized countries. Clinical presentations of diabetes are strongly related to the cardiovascular system, namely, coronary disease and angiopathic renal failure. Diabetes modifies the clinical course of arteriosclerosis by carrying the angiopathic process to a microvascular level, where typical microangiopathic lesions can be observed. The risk of developing atherosclerotic disease is 2-3 fold higher in diabetics than in nondiabetics and arterial hypertension reaches a prevalence of 40 to 80%. Authors analyse Arterial Hypertension in the context of Diabetes putting focus on the underlying pathophysiological mechanisms. Where considering the coronary disease (CD), its high prevalence among the diabetics is also emphasized, which is expressed by an increase of morbidity and mortality when compared to normal subjects. In diabetics not only the incidence of Acute Myocardial Infarction is higher, but also the long term prognosis is more complicated, a reality that the authors try to explain by anatomic and metabolic factors. The association of Diabetes plus hyperlipidemia represents undoubtedly one of the major factors that justify the worsening and progression of CD. Briefly, some interesting points that allow the understanding of this topic are described, pointing the pathogenic differences of types I and II and the clinical implications of their knowledge. Finally, the approach of Diabetes as a cardiovascular risk factor is discussed in a prophylactic perspective.

[Congestive heart insufficiency. Prophylactic aspects]

Since the therapeutic advances prolong survival of many patients suffering from cardiovascular pathology--the prevalence of chronic heart failure (CHF) had just doubled, being a common entity in a world whose individuals present a great increase in longevity. These considerations justify the renewed interest in this particular syndrome. Concepts, pathophysiology and compensatory mechanisms are briefly summarized, putting emphasis on the advantage of pharmacologically interrupt the vicious loop of the compensatory mechanisms, that could play a deleterious role in the syndrome. Neurohormonal responses and the "pivotal" role of angiotensine II in CHF pathology are also discussed, emphasizing the benefits of angiotensin converting enzyme inhibitors (ACEI) when treating patients presenting heart failure. Questions addressed to its prescription at an early stage, (classes II and III of NYHA--to prevent the progressive exhaustion of the failing heart) are also considered. When approaching the preventive measures in a wide perspective, primary, secondary and tertiary types of preventive options are described. ACEI use for the least advanced clinical stages of CHF (class II and III) would represent a tertiary type of CHF prevention.

[Collapse of the aortic valve in dilated myocardiopathies: echocardiographic study]

In order to clarify the early systolic partial closure (notching) of aortic valve in patients (pts) with dilated cardiomyopathy (DC), authors (AA) evaluated the M-mode echocardiograms corresponding to 41 pts with DC. Pts were separated in two groups, according to the presence of systolic notching: group A (18 pts) presenting systolic notching; group B (23 pts) in which no systolic notching was observed. For each group, the same echocardiographic parameters were evaluated related to aortic root, left atrium, left ventricule (LV), aortic valve and mitral valve. Both groups were compared statistically. Results--Group A presented a reduced motion of aortic root and greater initial maximal aortic cuspids separation. AA therefore conclude that in pts with DC the systolic notching has no eventual relation with mitral regurgitation. In this setting no conclusions about LV function can be inferred, and it is suggested that systolic notching may bear some relation with differences in the distribution of transvalvular aortic flow.