Enhancing beneficial antioxidants in fruits: a plant physiological perspective

The aim of this review is to present an outline of the physiological perspectives of beneficial antioxidant production in fruit. The drive to enhance the consumption of fruit and vegetables in the human diet is linked with positive effects of beneficial antioxidants impacting on health promotion. We briefly outline our physiological understanding of environmental processes which induce the production of reactive oxygen species and how antioxidants prevent plant cellular damage. More specifically, we describe the impact that environmental stresses, such as drought and radiation, have on the production of endogenous antioxidants and how these stresses can be incorporated into novel experimental crop growing systems to achieve high antioxidant concentrations in fruits. This includes in particular the use of irrigation application techniques and enhanced light reflectance to increase the concentrations of bioactive compounds such as ellagic acid and ascorbic acid.     

Bacteria as vitamin suppliers to their host: a gut microbiota perspective

1. Download : Download high-res image (156KB)
2. Download : Download full-size image

Highlights► Humans lack the biosynthetic capacity for most vitamins. ► Vitamins must thus be provided exogenously by nutritionally balanced diets. ► Members of the human gut microbiota can supply their host with microbially synthesized vitamins. ► Fermented milks with high levels of B-group vitamins can be produced by lactic acid.     

Vitamin D: a clinical perspective

Vitamin D has been the focus of considerable recent scientific study and media attention because of a growing appreciation of its potential importance in extra‐skeletal health. This ‘Perspective’ presents data supporting the viewpoint that physicians should not routinely test vitamin D levels in the general population but should routinely endorse vitamin D supplementation at levels recommended by the Institute of Medicine. It further reasons that it is unadvisable to recommend intentional limited sun exposure as a source of vitamin D.     

Wood ants and a geometrid defoliator of birch: predation outweighs beneficial effects through the host plant

Soil amelioration by a wood-ant species and its consequences for the larval performance of autumnal moths feeding on mountain birch were studied at various distances from the nest mound. Soil nitrate and ammonium nitrogen did not show any clear relationship with distance. However, trees growing in the mound had over 20% more foliar nitrogen than more distant trees. When moth larvae were experimentally protected from predation, their survival rate and final weight tended to decrease with increasing distance. In a laboratory experiment with detached leaves, the relative growth rate of larvae was roughly 30% higher on leaves from trees located on the mound. Differences in larval performance refute the Plant Stress Hypothesis proposed by T.C.R. White and support P.W. Price's Plant Vigor Hypothesis. Predation by ants was examined along the same gradient in trees with and without a glue band that excluded ants from the canopy. Reduction in the daily survival rate of larvae attributable to ant predation was about 35% in trees growing in the mound and around 5% at a distance of 20 m. Other things being equal, about 25 times more larvae entering the penultimate instar would achieve the pupal stage outside the wood-ant territory than in the vicinity of the mound. While both the fertilizing and predatory influence of wood ants is clear, the domain of predation is much larger than the area where trees and their herbivores can exploit enhanced nutrient levels in and around ant mounds. The existence of undamaged green islands around ant mounds in otherwise totally defoliated mountain-birch forests cannot be explained by soil amelioration by wood ants but rather by their predatory activity. Received: 21 November 1996 / Accepted: 8 September 1997     

Companion animal parasitology: a clinical perspective

In recent years there have been many changes to the ways that clinical veterinary science is conducted and nowhere is this more evident than in companion animal practice. Veterinarians working with pet dogs and cats are facing new challenges associated with the emergence and re-emergence of parasitic diseases. Some, such as Neospora caninum, have been recently recognised; others like Giardia and Cryptosporidium have been reported with increasing frequency, in part as a result of laboratory tests with improved sensitivity and specificity. In many regions, the emergence of parasitic diseases has been a consequence of pet travel and exotic diseases pose a unique diagnostic challenge for the veterinarian, as the index of suspicion for these conditions may be absent. The ranges of certain vector-borne diseases such as babesiosis, hepatozoonosis, ehrlichiosis, leishmaniasis and dirofilariasis are extending due to ecological and climatic changes and enhanced by animals with subclinical infection returning home from endemic areas. In companion animal practice, veterinarians have the additional responsibility of providing accurate information about the zoonotic transmission of parasite infections from pets, especially to those most vulnerable such as children, the elderly and the immunocompromised. Effective education is vital to allay public concerns and promote responsible pet ownership.     

Dengue and dengue haemorrhagic fever: Indian perspective

The relationship of this country with dengue has been long and intense. The first recorded epidemic of clinically dengue-like illness occurred at Madras in 1780 and the dengue virus was isolated for the first time almost simultaneously in Japan and Calcutta in 1943–1944. After the first virologically proved epidemic of dengue fever along the East Coast of India in 1963–1964, it spread to allover the country. The first full-blown epidemic of the severe form of the illness, the dengue haemorrhagic fever/dengue shock syndrome occurred in North India in 1996. Aedes aegypti is the vector for transmission of the disease. Vaccines or antiviral drugs are not available for dengue viruses; the only effective way to prevent epidemic degure fever/dengue haemorrhagic fever (DF/DHF) is to control the mosquito vector, Aedes aegypti and prevent its bite. This country has few virus laboratories and some of them have done excellent work in the area of molecular epidemiology, immunopathology and vaccine development. Selected work done in this country on the problems of dengue is presented here.     

The role of fever in the infected host

Sepsis is a highly lethal clinical syndrome characterized by a systemic inflammatory response to infection. Fever, a non-specific acute-phase response, has been associated with improved survival and shortened disease duration in non-life-threatening infections. However, the influence of fever and the effects of antipyresis in patients with sepsis has not been prospectively studied in humans. This paper reviews the state of our knowledge concerning the biological effects of fever in infected hosts and the influence of fever and antipyretic therapy on survival during sepsis in experimental models and in man.     

Dengue and dengue haemorrhagic fever: implications of host genetics

Little is known of the role of human leucocyte antigen (HLA) alleles or non-HLA alleles in determining resistance, susceptibility or the severity of acute viral infections. Dengue fever (DF) and dengue haemorrhagic fever (DHF) are suitable models for immunogenetic studies, yet only superficial efforts have been made to study dengue disease to date. DF and DHF can be caused by both primary and secondary infection by any of the four serotypes of the dengue virus. Differences in host susceptibility to infectious disease and disease severity cannot be attributed solely to the virus virulence. Variations in immune response, often associated with polymorphism in the human genome, can now be detected. Data on the influence of human genes in DF and DHF are discussed here in relation to (1) associations between HLA polymorphism and dengue disease susceptibility or resistance, (2) protective alleles influencing progression to severe disease, (3) alleles restricting CD4(+) and CD8(+) T lymphocytes, and (4) non-HLA genetic factors that may contribute to DHF evolution. Recent discoveries regarding genetic associations in other viral infections may provide clues to understanding the development of end-stage complications in dengue disease. The scanty positive data presented here indicate a need for detailed genetic studies in different ethnic groups in different countries during the acute phase of DF and DHF on a larger number of patients.     

Acquisition of obligate mutualist symbionts during the larval stage is not beneficial for a coral host

Theory suggests that the direct transmission of beneficial endosymbionts (mutualists) from parents to offspring (vertical transmission) in animal hosts is advantageous and evolutionarily stable, yet many host species instead acquire their symbionts from the environment (horizontal acquisition). An outstanding question in marine biology is why some scleractinian corals do not provision their eggs and larvae with the endosymbiotic dinoflagellates that are necessary for a juvenile's ultimate survival. We tested whether the acquisition of photosynthetic endosymbionts (family Symbiodiniaceae) during the planktonic larval stage was advantageous, as is widely assumed, in the ecologically important and threatened Caribbean reef‐building coral Orbicella faveolata. Following larval acquisition, similar changes occurred in host energetic lipid use and gene expression regardless of whether their symbionts were photosynthesizing, suggesting the symbionts did not provide the energetic benefit characteristic of the mutualism in adults. Larvae that acquired photosymbionts isolated from conspecific adults on their natal reef exhibited a reduction in swimming, which may interfere with their ability to find suitable settlement substrate, and also a decrease in survival. Larvae exposed to two cultured algal species did not exhibit differences in survival, but decreased their swimming activity in response to one species. We conclude that acquiring photosymbionts during the larval stage confers no advantages and can in fact be disadvantageous to this coral host. The timing of symbiont acquisition appears to be a critical component of a host's life history strategy and overall reproductive fitness, and this timing itself appears to be under selective pressure.     

A proteomic view of the host-pathogen interaction: The host perspective

The host-pathogen interaction represents a complex and dynamic biological system. The outcome of this interaction is dependent on the microbial pathogen properties to establish infection and the ability of the host to control infection. Although bacterial pathogens have evolved a variety of strategies to subvert host defense functions, several general mechanisms have been shown to be shared among these pathogens. As a result, host effectors that are critical for pathogen entry, survival and replication inside the host cells have become a new paradigm for antimicrobial targeting. This review focuses on the potential utility of a proteomics approach in defining the host-pathogen interaction from the host's perspective.     

Targeting the HIV-protease in AIDS therapy: a current clinical perspective

This review deals with clinical applications of compounds that inhibit the action of the protease encoded within the genome of human immunodeficiency virus (HIV). The HIV-protease is essential for viral maturation and represents an important therapeutic target in the fight against AIDS. Following a brief overview of the enzyme structure and function, the article focuses on a number of peptide and non-peptide based HIV-protease inhibitors that are in current clinical use. These drugs are discussed both with respect to their efficacy in treatment of AIDS, and to problems related to insurgence of viral resistance and side effects seen to date in patient populations.     

Overwintering strategy of endoparasitoids in Chilo suppressalis: a perspective from the cold hardiness of a host

Although parasitoids ultimately kill their host, koinobiont parasitoids must protect not only themselves but also their hosts against extreme environments. In this study, the parasitism rate of Chilo suppressalis Walker (Lepidoptera: Pyralidae) was investigated, and the average body weights, supercooling points, and concentrations of glycerol (acting as a cryoprotectant) in the hemolymph were compared between parasitized and non‐parasitized larvae. Five species of koinobiont endoparasitoids parasitized the overwintering C. suppressalis larvae and the total parasitism rate was 47.6% (n = 1 537). Average body weight of parasitized larvae was significantly lower than that of non‐parasitized larvae, and the parasitism rate of the lighter group (20–30 mg) was highest. The supercooling point of parasitized C. suppressalis larvae (?15.7 ± 0.3 °C) was significantly lower than that of the non‐parasitized larvae (?14.3 ± 0.2 °C). In addition, supercooling points were not correlated with body weights between parasitized and non‐parasitized larvae, indicating that cold hardiness of parasitized larvae was enhanced by endoparasitoids. Furthermore, the concentration of glycerol in the hemolymph was significantly higher in parasitized larvae (205.0 ± 7.1 μmol ml^?1) than in non‐parasitized larvae (169.8 ± 14.4 μmol ml^?1), which suggests that the mechanism that decreases the supercooling point of parasitized larvae was associated with glycerol. All these results indicated that the cold hardiness of parasitized C. suppressalis larvae was enhanced by their endoparasitoids, which benefitted overwintering endoparasitoids.