Calmodulin: an overview

Calmodulin is a 16,700-dalton Ca2+-binding protein ubiquitous in the eukaryotes. It has no intrinsic enzymatic activity, but it regulates a wide spectrum of enzymes that control many basic cellular processes, ranging from the metabolism of cyclic nucleotides, Ca2+, and glycogen to contractile activity and stimulus-secretion coupling. Mounting evidence now indicates that calmodulin is the major intracellular Ca2+ receptor that remained elusive despite three decades of extensive work by many investigators.     

Chikungunya: an overview

Chikungunya (CHIK), a mosquito borne debilitating disease, is caused by CHIK virus, an alphavirus belonging to the family Togaviridae. The sudden onset of very high fever along with rash, and severe arthralgia especially in the small joints of hands and toes are the characteristics of the disease. It was first reported from Tanzania in 1952–53 and spread subsequently to sub-Saharan Africa, South East Asia and Pacific causing large epidemics. The virus exists in three genotypes, the Asian, West African and East Central South African that are responsible for outbreaks in the respective areas. The first outbreak in Asia was in Bangkok in 1958 followed by other Asian countries. India experienced massive outbreaks of CHIK in the 1960s and early 70s mainly in cities. After a gap of 32 years an explosive outbreak of CHIK devastated the country affecting more than 1.4 million people in 13 states. The epidemic also witnessed many unusual clinico-pathological complications including CHIK associated deaths and mother to child transmission. High morbidity with severe arthralgia persisted for several months made the people mentally and physically weak. This review describes CHIK in general and highlights the various clinico-pathological aspects observed during the recent outbreak.     

Polyhydroxyalkanoates: an overview

Polyhydroxyalkanoates have gained major importance due to their structural diversity and close analogy to plastics. These are gaining more and more importance world over. Different sources (natural isolates, recombinant bacteria, plants) and other methods are being investigated to exert more control over the quality, quantity and economics of poly(3-hydroxybutyrate) (PHB) production. Their biodegradability makes them extremely desirable substitutes for synthetic plastics. The PHB biosynthetic genes phbA, phbB and phbC are clustered and organized in one phbCAB operon. The PHB pathway is highly divergent in the bacterial genera with regard to orientation and clustering of genes involved. Inspite of this the enzymes display a high degree of sequence conservation. But how similar are the mechanisms of regulation of these divergent operons is as yet unknown. Structural studies will further improve our understanding of the mechanism of action of these enzymes and aid us in improving and selecting better candidates for increased production. Metabolic engineering thereafter promises to bring a feasible solution for the production of "green plastic".     

Hantaviruses: an overview

Hantaviruses are a newly emerging group of rodent-borne viruses that have significant zoonotic potential. Human infection by hantaviruses can result in profound morbidity and mortality, with death rates as high as 50%, and potentially long-term cardiovascular consequences. Hantaviruses are carried by peridomestic and wild rodents worldwide and have occasionally been linked to infections in laboratory rodents. Because these viruses have been associated with significant human disease, they have become the subject of intense scientific investigation. In this review the reader is introduced to the hantaviruses, including hantavirus diseases and their pathogenesis. A review of the biology, morphology, and molecular biology of the hantaviruses with a brief overview of the ecology and biology of hantavirus-rodent pairs is also included. The risks of occupational exposure to hantaviruses, diagnosis of hantavirus infections, and methods for handling potentially infected rodents and tissues are discussed as well.     

Hydroxyurea: an overview

Hydroxyurea has been a compound of scientific and clinical interest for over 100 years. A small molecule with many biological properties, hydroxyurea is used in a number of myeloproliferative, neoplastic, and non-hematological diseases. Recently, the agent has been investigated for use in the treatment of Human Immunodeficiency Virus (HIV) disease. Hydroxyurea is associated with dose related bone marrow suppression, crosses the placenta, and is excreted in breast milk. Toxicity is often managed through dose titration. Although adequate attention must be paid to the drug's use in pregnancy and during breast feeding, hydroxyurea's ease of administration, multiplicity of clinical effects, and low cost ensure the drug a place in therapy for years to come.     

Babesiosis in Italy: an overview

Babesiosis is a tick-transmitted disease caused by hematotropic parasites of the genus Babesia. Tick-borne diseases (TBD) have increasingly been recognized in the world as public health problems. The piroplasms are transmitted by ticks and are able to infect a wide variety of vertebrate hosts which are competent in maintaining the transmission cycle. Babesiosis occurrence is usually linked to seasonal variations that affect the vector, but climatic changes have not been common in the subtropical regions of Italy, especially during the last few years. This paper is aimed at compiling information about babesiosis in Italy both from the available literature and from the records of our Centre. Recent biotechnological approaches have aid to the detection of parasites and the monitoring of tick vectors. Moreover, our research has lately been focused on the investigation of the presence of Babesia parasites in wild animals, yielding very interesting results.     

Bacterial classification: an overview

Classification of bacteria evolved from limited subjective groupings to general, more objective arrangements based on overall phenotypic similarities. However, classifications based on phenotypic characters lack stability, whereas those based on genetic relatedness tend to be stable. DNA-DNA hybridization has proven to be extremely useful in resolving taxonomic problems at the species level. Broad relationships among bacteria have been identified by comparing ribosomal RNA cistrons; however, many groups based on ribosomal RNA analysis are not easily definable in terms of phenotypic similarities. Unless resolved, these problems could lead to the establishment of two separate classification systems, one phylogenetic and the other practical.     

Hepatitis E: an overview

The hepatitis E virus (HEV) is a non-enveloped, positive-sense, single-stranded RNA virus with icosahedral symmetry. Although it is related to the alpha-virus superfamily, the HEV is classified as a separate Hepatitis E-like viruses genus. Infection in humans occurs in sporadic and epidemic forms and can cause an acute, self-limited, icteric hepatitis. Recent studies indicate the existence of a reservoir in animals.     

Genetic ecotoxicology: an overview

The techniques currently available for detecting genotoxin exposure are briefly described and evaluated with regard to the goals of genetic ecotoxicology. The occurrence and significance of genotoxin-induced neoplasia in marine organisms is described. Although there are numerous examples of hotspots where tumour incidences in fish and shellfish have been correlated with raised concentrations of anthropogenic chemicals, causal mechanisms are seldom established. Insufficient information is available to gauge the seriousness of genotoxicity for marine organisms on regional or global scales. The possibility of using marine organisms as sentinels to provide early warning of potential threats to Man is examined. Recognition of the genotoxic disease syndrome in lower animals highlights the need to explore the relationships between DNA damage (adduct formation, gene mutations, etc.) and its phenotypic consequences. Within a given population, not all individuals are equally susceptible to pollutant toxicity (including genotoxicity). The potential for using similarities in phenotypic traits to recognise subsets of individuals within populations possessing similar genotypes is discussed. Changes in heterozygosity and the evolution of genetically resistant populations following exposure to pollution are evaluated in the context of genetic ecotoxicology. Risk assessment procedures are required which enable genotoxin exposure to be related to specific consequences at the community and ecosystem levels. This necessitates both a sound scientific understanding of the mechanisms involved and the development of pragmatic ecotoxicological tools that can be employed by environmental managers.     

Gibberellin conjugates: an overview

This article surveys the currently isolated and identified GA conjugates, their synthesis and evaluates modern methods for analysing GA glucose conjugates. The metabolism of applied GAs in higher plant systems leading, in most cases, to GA conjugates is also considered. The enzymology of the formation and hydrolysis of GA glucose conjugates is discussed in connection with their possible physiological function.Abbreviations API = atmospheric pressure ionization - FAB = fast atom bombardment - GA-GE = gibberellin glucosyl ester - GA-O-G = gibberellin-O-glucoside - GC = gas chromatography - GC-MS = combined gas chromatography-mass spectrometry - HPLC = high performance liquid chromatography - LC-MS = combined high performance liquid chromatography-mass spectrometry - MS = mass spectrometry - NMR = nuclear magnetic resonance - PME = permethyl - SIM = selected ion monitoring - TMS = trimethylsilyl     

Monocot relationships: an overview

In 10 years, the monocots have gone from being one of the least studied and most phylogenetically misunderstood groups of the angiosperms to one of the best characterized. Based on analyses of seven genes representing all three genomes, the following clades have high bootstrap support: Acorales (with the single genus Acorus) is sister to the rest of the monocots, followed successively by Alismatales (including Araceae and Tofieldiaceae), Petrosaviales, Dioscoreales/Pandanales, Liliales, Asparagales, and finally a polytomy of Arecales, Commelinales/Zingiberales, Dasypogonaceae, and Poales. Many of these results also have support from at least some morphological data, but some are unique to the trees created from DNA sequence data. Monocots have been shown in molecular clock studies to be at least 140 million years old, and all major clades and most families date to well before the end of the Cretaceous. More data are required to clarify the positions of the remaining unclearly placed orders, Asparagles, Liliales, and Arecales, as well as Dasypogonaceae. More sequences from the nuclear and mitochondrial genomes are also needed to complement those from the plastid genome, which is the most sampled and thus far most pattern-rich.