Effects of low temperature,genotype and culture media on in vitro androgenic answer of pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.)

Anther culture is one of the most important and useful tool to create pure lines for plant breeding programs rapidly. Some pepper genotypes are recalcitrant and embryogenic frequency in anther culture is still low or reaction is not observed at all. Temperature stress (low or high) can facilitate switching the microspore to sporophyte developmental pathway. In this study, some differences were found in embryogenic reaction among the pepper genotypes and culture media variants, depending on duration of cold treatment of flower buds. Experimental results indicated that embryogenic efficiency decreased under low-temperature stress. Nevertheless, positive effect of cold pretreatment on direct embryo induction was obtained in four genotypes—cultivar Hebar, hybrid 50/01 and lines 668/02 and 1312/02. Increasing of embryogenic reaction after cold pretreatment was observed in media variants C (24 h) and MS-3 + (24 and 48 h), while on medium variant C-0 direct embryo formation was registered only after 48 h cold pretreatment. These results show that the donor genotypes have specific requirements for type and duration of temperature pretreatment and also culture media for induction of androgenesis with higher frequency.     

Developmental study of tripeptidyl peptidase I activity in the mouse central nervous system and peripheral organs

Tripeptidyl peptidase I (TPPI) — a lysosomal serine protease — is encoded by the CLN2 gene, mutations that cause late-infantile neuronal ceroid lipofuscinosis (LINCL) connected with profound neuronal loss, severe clinical symptoms and early death at puberty. Developmental studies of TPPI activity levels and distribution have been done in the human and rat central nervous systems (CNS) and visceral organs. Similar studies have not been performed in mouse. In this paper, we follow up on the developmental changes in the enzyme activity and localization pattern in the CNS and visceral organs of mouse over the main periods of life — embryonic, neonate, suckling, infantile, juvenile, adult and aged — using biochemical assays and enzyme histochemistry. In the studied peripheral organs (liver, kidney, spleen, pancreas and lung) TPPI is present at birth but further its pattern is not consistent in different organs over different life periods. TPPI activity starts to be expressed in the brain at the 10th embryonic day but in most neuronal types it appears at the early infantile period, increases during infancy, reaches high activity levels in the juvenile period and is highest in adult and aged animals. Thus, in mice TPPI activity becomes crucial for the neuronal functions later in development (juvenile period) than in humans and does not decrease with aging. These results are essential as a basis for comparison between normal and pathological TPPI patterns in mice. They can be valuable in view of the use of animal models for studying LINCL and other neurodegenerative disorders.     

Anther culture in pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) in vitro

Pepper (Capsicum annuum L.) is an important vegetable crop that can be improved using plant tissue culture and biotechnology. However, it is difficult to develop appropriate breeding material by in vitro cultivation in this species. Haploid plant production is useful in the breeding programs to facilitate recovery of recessive mutations and unique genetic recombinations. In embryogenesis, haploid formation from pollen in anther culture is a scientifically advanced, but controversial system. Various techniques for haploid plant regeneration are used to establish an efficient double haploid production method. The purpose of this article is to summarize, through comparison, results in pepper anther culture, problems associated with work in this field, and the influence of critical factors for successful embryo formation and plantlet development.     

Engineering of the membrane of fibroblast cells with virus-specific antibodies: A novel biosensor tool for virus detection

A novel concept for the assay of viral antigens is described. The methodological approach is based on a membrane-engineering process involving the electroinsertion of virus-specific antibodies in the membranes of fibroblast cells. As a representative example, Vero fibroblasts were engineered with antibodies against Cucumber mosaic virus (CMV) and used for the construction of an ultra-sensitive miniature cell biosensor system. The attachment of a homologous virus triggered specific changes to the cell membrane potential that were measured by appropriate microelectrodes, according to the principle of the bioelectric recognition assay (BERA). No change in the membrane potential was observed upon cell contact with the heterologous cucumber green mottle mosaic virus (CGMMV). Fluorescence microscopy observations showed that attachment of CMV particles to membrane-engineered cells was associated with membrane hyperpolarization and increased [Ca(2+)](cyt). In an additional field-based application, we were able to detect CMV-infected tobacco plants at an essentially 100% level of accuracy.     

Preservation of photosynthetic electron transport from senescence-induced inactivation in primary leaves after decapitation and defoliation of bean plants

The comparative effects of decapitation and defoliation on the senescence-induced inactivation of photosynthetic activity in primary leaves of bean plants were investigated. Decapitation was performed during different phases of bean plant ontogenesis, immediately after the appearance of the 1st, 2nd, 3rd and 4th composite leaf. In addition, we examined a variant with primary leaves and stem with an apical bud, but without composite leaves, i.e. defoliated plants. Analyses of chlorophyll fluorescence, millisecond delayed fluorescence and absorption at 830nm in primary leaves were undertaken to investigate the alterations in photosystems II and I electron transport during the decapitation-induced delayed senescence in the non-detached leaves. Analysis of the OKJIP transients using the JIP-test (see [Strasser R, Srivastava A, Tsimilli-Michael M. Analysis of the chlorophyll a fluorescence transient. In: Papageorgiou G, Govindjee, editors. Chlorophyll a fluorescence: a signature of photosynthesis. The Netherlands: Kluwer Academic Publishers, 2004; pp. 321-362]) showed an increase in several biophysical parameters of photosystem II in decapitated plants, specifically, the density of active reaction centers on a chlorophyll basis, the yields of trapping and electron transport, and the performance index. We also observed a decrease in the absorbed light energy per reaction center. Such a decrease in light absorption could be a result of the photosystem II down regulation that appeared as an increase in Q(B)-non-reducing photosystem II centers. The effect was identical when all leaves except the primary leaves were removed. The variant with a preserved apical bud, the defoliated plant, showed values similar to those of decapitated plants with primary leaves only. The changes in the induction curves of the delayed fluorescence also indicated an acceleration of electron transport beyond photosystem II in the decapitated and in defoliated plants. In these plants, the photosystem I-driven electron transport was accelerated, and the size of the plastoquinone pool was enhanced. It was established that decapitation can retard the senescence of primary leaves, can expand leaf life span and can cause activation of both photosystems I and II electron transport. The decapitation procedure shows similarities to the process of defoliation. The overcompensation effect that is developed after defoliation could initially be manifested as an acceleration of the linear photosynthetic electron flow in the rest of the leaves.     

Evaluation of antimicrobial resistance among <Emphasis Type="Italic">Salmonella</Emphasis> and <Emphasis Type="Italic">Shigella</Emphasis> isolates in the University Hospital “St. George,” Plovdiv,Bulgaria

The aim of this work is to study the epidemiology and antimicrobial resistance to the most commonly used antibiotics for the treatment of acute gastroenteritis caused by Salmonella and Shigella at the largest Bulgarian hospital—University Hospital “St. George,” Plovdiv—for the period 2009–2013. Two hundred ninety strains were in vitro tested for resistance to 15 antimicrobial agents. The presence of extended-spectrum beta-lactamases (ESBLs) was demonstrated by a variety of specialized tests. For comparison, a collection of 28 strains submitted by the National Reference Laboratory (NRL) “Enteric Infections” at the National Center of Infectious and Parasitic Diseases (NCIPD), Sofia, was also tested for the production of ESBLs. In isolates, phenotypically demonstrated as ESBL producers, polymerase chain reaction (PCR) detection of the genes bla-CTX-M, bla-SHV, and bla-TEM was performed. Among the 290 tested isolates, only two— Salmonella serotype Livingstone and Shigella flexneri—were phenotypically proven to be ESBL producers. Only 4 strains from the collection of 28, submitted from the NRL “Intestinal Infections” in NCIPD, Sofia, were phenotypically confirmed as ESBL producers. The presence of the bla-CTX-M gene was detected in all of the tested strains (4 from NRL, NCIPD, Sofia, and 2 from the University Hospital St. George, Plovdiv), the bla-SHV gene only in strain S. Livingstone from Plovdiv, and the bla-TEM gene in two from Sofia and one (again S. Livingstone) from Plovdiv. In conclusion, Salmonella and Shigella isolates from patients hospitalized at the University Hospital St. George, Plovdiv, with acute gastroenteritis demonstrate good susceptibility to the most commonly used antibiotic agents, including azithromycin.     

Long-term resistance to tomato spotted wilt virus in transgenic tobacco cultivars expressing the viral nucleoprotein gene: greenhouse and field tests

We examined the resistance phenotype of a large number of transgenic tobacco plants originating from 12 commercial (Nicotiana tabacum) cultivars expressing the sense form of the nucleoprotein (N) gene of L3, a Bulgarian isolate of tomato spotted wilt virus (TSWV). The analysis revealed that transgenic plants are completely protected against the homologous L3 isolate of TSWV irrespective of whether or not they contain detectable levels of translational product. The effectiveness of protection against the virus was investigated upon mechanical inoculation under greenhouse conditions and in field trials. Non-segregating resistant lines were selected and the inheritance of the resistance to TSWV was analysed in successive generations (R₃–R₆). Extensive tests under controlled conditions and two-year field trials proved that the resistance to TSWV is stable in different environments and is a stably inherited trait.