Non-plant Sources Research Articles

Hyperkalemia treatment Standard.

Hyperkalemia is a common electrolyte disturbance in both inpatient and outpatient clinical practice. The severity and associated risk depends on the underlying cause and rate of K+ increase. Acute hyperkalemia requires immediate attention due to potentially life-threatening manifestations resulting from the rapid rise in plasma K+ concentration. Treatment is initially focused on stabilizing the cardiac membrane, followed by maneuvers to shift K+ into the cell, and ultimately initiating strategies to decrease total body K+ content. Chronic hyperkalemia develops over a more extended period of time and manifestations tend to be less severe. Nevertheless, the disorder is not benign since chronic hyperkalemia is associated with increased morbidity and mortality. The approach to patients with chronic hyperkalemia begins with a review of medications potentially responsible for the disorder, ensuring effective diuretic therapy, and correcting metabolic acidosis if present. The practice of restricting foods high in K+ potassium to manage hyperkalemia is being reassessed since the evidence supporting the effectiveness of this strategy is lacking. Rather, dietary restriction should be more nuanced focusing on reducing intake of non-plant sources of K+. Down titration and/or discontinuation of renin-angiotensin-aldosterone inhibitors should be discouraged since these drugs improve outcomes in patients with heart failure and proteinuric kidney disease. In addition to other conservative measures, K+ binding drugs and SGLT2 inhibitors can assist in maintaining use of these drugs.

Characterization of chloroplast ribulose-5-phosphate-3-epimerase from the microalga Chlamydomonas reinhardtii.

Carbon fixation relies on Rubisco and 10 additional enzymes in the Calvin-Benson-Bassham cycle. Epimerization of xylulose-5-phosphate (Xu5P) into ribulose-5-phosphate (Ru5P) contributes to the regeneration of ribulose-1,5-bisphosphate, the substrate of Rubisco. Ribulose-5-phosphate-3-epimerase (RPE, EC 5.1.3.1) catalyzes the formation of Ru5P, but it can also operate in the pentose-phosphate pathway by catalyzing the reverse reaction. Here, we describe the structural and biochemical properties of the recombinant RPE isoform 1 from Chlamydomonas (Chlamydomonas reinhardtii) (CrRPE1). The enzyme is a homo-hexamer that contains a zinc ion in the active site and exposes a catalytic pocket on the top of an α8β8 triose isomerase-type barrel as observed in structurally solved RPE isoforms from both plant and non-plant sources. By optimizing and developing enzyme assays to monitor the reversible epimerization of Ru5P to Xu5P and vice versa, we determined the catalytic parameters that differ from those of other plant paralogs. Despite being identified as a putative target of multiple thiol-based redox modifications, CrRPE1 activity is not affected by both reductive and oxidative treatments, indicating that enzyme catalysis is insensitive to possible redox alterations of cysteine residues. We mapped phosphorylation sites on the crystal structure, and the specific location at the entrance of the catalytic cleft supports a phosphorylation-based regulatory mechanism. This work provides an accurate description of the structural features of CrRPE1 and an in-depth examination of its catalytic and regulatory properties highlighting the physiological relevance of this enzyme in the context of photosynthetic carbon fixation.

Diversity and Pathobiology of an Ilarvirus Unexpectedly Detected in Diverse Plants and Global Sequencing Data.

High-throughput sequencing (HTS) and sequence mining tools revolutionized virus detection and discovery in recent years, and implementing them with classical plant virology techniques results in a powerful approach to characterize viruses. An example of a virus discovered through HTS is Solanum nigrum ilarvirus 1 (SnIV1) (Bromoviridae), which was recently reported in various solanaceous plants from France, Slovenia, Greece, and South Africa. It was likewise detected in grapevines (Vitaceae) and several Fabaceae and Rosaceae plant species. Such a diverse set of source organisms is atypical for ilarviruses, thus warranting further investigation. In this study, modern and classical virological tools were combined to accelerate the characterization of SnIV1. Through HTS-based virome surveys, mining of sequence read archive datasets, and a literature search, SnIV1 was further identified from diverse plant and non-plant sources globally. SnIV1 isolates showed relatively low variability compared with other phylogenetically related ilarviruses. Phylogenetic analyses showed a distinct basal clade of isolates from Europe, whereas the rest formed clades of mixed geographic origin. Furthermore, systemic infection of SnIV1 in Solanum villosum and its mechanical and graft transmissibility to solanaceous species were demonstrated. Near-identical SnIV1 genomes from the inoculum (S. villosum) and inoculated Nicotiana benthamiana were sequenced, thus partially fulfilling Koch's postulates. SnIV1 was shown to be seed-transmitted and potentially pollen-borne, has spherical virions, and possibly induces histopathological changes in infected N. benthamiana leaf tissues. Overall, this study provides information to better understand the diversity, global presence, and pathobiology of SnIV1; however, its possible emergence as a destructive pathogen remains uncertain.

The Judges' Considerations Against Sentence for Narcotics Abuse Category I

The younger generation is being targeted as the threat of drug seizures rises in Indonesia. Narcotics are substances or drugs that can alter consciousness, cause loss of feeling, lessen or eliminate pain, and cause dependence. They can be derived from plants or non-plant sources and synthetic or semi-synthetic. As a result, drug users who commit crimes need rehabilitation in order to overcome their drug use. For those who commit drug crimes, rehabilitation is a form of punishment with the objective of healing or treatment. However, in practice, judges frequently favor to sentence drug offenders to prison terms and fines, even though offenders can also be sent to rehabilitation. This empirical normative legal study uses primary and secondary data as its data sources and fieldwork and library research as its data collection methods. According to the study's findings, the judge's factors in establishing that the defendant's actions met the requirements of Article 127, paragraph 1, letter an of Law Number 35 of 2009 Concerning Narcotics were taken into consideration in proving the defendant's actions (Narcotics Law). One example is the decision in the drug crime case at the Special Class II Gedong Tataan District Court, which is based on the accuracy of the evidence and the legal facts presented during the trial and the fulfillment of the elements of each of these crimes. It was argued that it was appropriate for the defendants to receive prison sentences and fines rather than engage in medical or social rehabilitation because their status as drug addicts or abuse victims had not been established.

Ethnoveterinary Study of Plant-Based Remedies for Treating Diseases in Small Ruminants in Maputo Province, Mozambique.

Small ruminants, particularly goats and sheep, are key livestock species in Mozambique, and their production is mainly undertaken by families. However, small ruminants are often plagued by diseases that can cause considerable economic damage. In this context, traditional remedies, including various plant species, have been widely used to manage these diseases. The aim of this study was to explore the use of plant-based remedies and other treatments for managing diseases in small ruminants in Maputo Province, Mozambique. Data collection involved conducting interviews with 44 small ruminant breeders across 5 districts in Maputo Province to identify the plants and other remedies commonly used for managing diseases in their animals. We identified a total of 38 plant species belonging to 22 families. Among these plants, four were not identified by their scientific name. The most important plants reported were Cissus quadrangularis, Euphorbia kirkii, and Aloe sp., with Cissus quadrangularis being particularly noteworthy as it was frequently cited for the treatment of wounds. The most commonly cited botanical families were Fabaceae, Euphorbiaceae, and Asphodelaceae. Interestingly, in addition to plant-based remedies, we also identified other nonplant sources of treatment, such as alkaline batteries, which are commonly used to treat wounds in small ruminants. The use of plants for ethnoveterinary purposes remains prevalent in Maputo province, with older breeders serving as the primary custodians of this traditional knowledge. Efforts should be made to document and share the knowledge of these older breeders, ensuring that it is not lost over time. This preservation of ethnoveterinary knowledge can contribute to sustainable livestock management and support the wellbeing of both rural communities and their animals.

Sarcopenia Is an Independent Prognostic Factor for Squamous Cell Carcinoma of the Cervix Treated With Concurrent Chemoradiotherapy.

To investigate sarcopenia as a predictor of prognosis before concurrent chemoradiotherapy (CCRT) in patients with squamous cell carcinoma (SCC) of the cervix using the new psoas muscle index (PMI) cutoff value for sarcopenia in Japanese women. We included 134 patients with SCC of the cervix treated with CCRT. CT images were taken within one month before treatment. Measurements of PM and skeletal muscle (SM) area were taken at the L3 level using a CT image analysis system (Synapse Vincent). Whole-pelvic external beam radiotherapy (EBRT) with 50 Gy was performed. High-dose-rate intracavitary brachytherapy and boost EBRT doses were administered. The patients received 40 mg/m2 of cisplatin weekly during CCRT. Kaplan-Meier analysis and the log-rank test were used to compare survival rates. The five-year overall survival (OS) and five-year progression-free survival of all 134 patients were 86.1% and 77.3%, respectively. Univariate analysis revealed that only PMI had a significant association with OS (PMI <3.92 cm2/m2 in the sarcopenia group vs. PMI ≥3.92 cm2/m2 in the non-sarcopenia group, p=0.0112), with no significant differences in age, advanced stage of disease, tumor size, lymph node enlargement, serum SCC, or SMI. Multivariate analysis revealed that PMI is the only independent prognostic factor for OS, but none of the factors were found to have a significant association with PFS. PMI as an indicator of sarcopenia was found to be an independent prognostic factor for patients with SCC of the cervix who underwent CCRT.

Crystal structure of chloroplastic thioredoxin z defines a type-specific target recognition.

Thioredoxins (TRXs) are ubiquitous disulfide oxidoreductases structured according to a highly conserved fold. TRXs are involved in a myriad of different processes through a common chemical mechanism. Plant TRXs evolved into seven types with diverse subcellular localization and distinct protein target selectivity. Five TRX types coexist in the chloroplast, with yet scarcely described specificities. We solved the crystal structure of a chloroplastic z-type TRX, revealing a conserved TRX fold with an original electrostatic surface potential surrounding the redox site. This recognition surface is distinct from all other known TRX types from plant and non-plant sources and is exclusively conserved in plant z-type TRXs. We show that this electronegative surface endows thioredoxin z (TRXz) with a capacity to activate the photosynthetic Calvin-Benson cycle enzyme phosphoribulokinase. The distinct electronegative surface of TRXz thereby extends the repertoire of TRX-target recognitions.

Sugarcane Omics: An Update on the Current Status of Research and Crop Improvement.

Sugarcane is an important crop from Poaceae family, contributing about 80% of the total world’s sucrose with an annual value of around US$150 billion. In addition, sugarcane is utilized as a raw material for the production of bioethanol, which is an alternate source of renewable energy. Moving towards sugarcane omics, a remarkable success has been achieved in gene transfer from a wide variety of plant and non-plant sources to sugarcane, with the accessibility of efficient transformation systems, selectable marker genes, and genetic engineering gears. Genetic engineering techniques make possible to clone and characterize useful genes and also to improve commercially important traits in elite sugarcane clones that subsequently lead to the development of an ideal cultivar. Sugarcane is a complex polyploidy crop, and hence no single technique has been found to be the best for the confirmation of polygenic and phenotypic characteristics. To better understand the application of basic omics in sugarcane regarding agronomic characters and industrial quality traits as well as responses to diverse biotic and abiotic stresses, it is important to explore the physiology, genome structure, functional integrity, and collinearity of sugarcane with other more or less similar crops/plants. Genetic improvements in this crop are hampered by its complex genome, low fertility ratio, longer production cycle, and susceptibility to several biotic and abiotic stresses. Biotechnology interventions are expected to pave the way for addressing these obstacles and improving sugarcane crop. Thus, this review article highlights up to date information with respect to how advanced data of omics (genomics, transcriptomic, proteomics and metabolomics) can be employed to improve sugarcane crops.

Herbicide resistant biotech crops and their import to Indian agriculture

Herbicide resistant (HR) biotech crops which include both the transgenic and non-transgenic ones are being grown in several countries for over 24 yr. Transgenic biotech crops are derived when an exogenous herbicide-resistant gene/s from non-plant sources is/are inserted into the desired crop plant. When the inserted genes stably integrate and express in the plant genome, the concerned plant behaves like a normal plant but with the acquired character, i.e. herbicide resistance. On the other hand, the non-transgenic biotech crops are generated for some herbicides (ALS-inhibiting and ACCase-inhibiting cyclohexane-diones) by selecting for target mutations in plant populations or by tissue culture or by mutation breeding. HR varieties have been developed for soybean, maize, cotton, canola, wheat, rice, sugar beet, alfalfa, etc. while the herbicides included glufosinate, dicamba, 2,4-D, phenmedipham, paraquat, imidazolinones, mesotrione, sulfonylureas, etc.

An evolutionary analysis identifies a conserved pentapeptide stretch containing the two essential lysine residues for rice L-myo-inositol 1-phosphate synthase catalytic activity.

A molecular evolutionary analysis of a well conserved protein helps to determine the essential amino acids in the core catalytic region. Based on the chemical properties of amino acid residues, phylogenetic analysis of a total of 172 homologous sequences of a highly conserved enzyme, L-myo-inositol 1-phosphate synthase or MIPS from evolutionarily diverse organisms was performed. This study revealed the presence of six phylogenetically conserved blocks, out of which four embrace the catalytic core of the functional protein. Further, specific amino acid modifications targeting the lysine residues, known to be important for MIPS catalysis, were performed at the catalytic site of a MIPS from monocotyledonous model plant, Oryza sativa (OsMIPS1). Following this study, OsMIPS mutants with deletion or replacement of lysine residues in the conserved blocks were made. Based on the enzyme kinetics performed on the deletion/replacement mutants, phylogenetic and structural comparison with the already established crystal structures from non-plant sources, an evolutionarily conserved peptide stretch was identified at the active pocket which contains the two most important lysine residues essential for catalytic activity.

Ethnomedicinal Knowledge for Management of Leeches in Assam

&lt;p&gt;Leech infestation is a common health problem in Assam that affects people of all ages, sexes and even livestock. Ethnomedicinal practice for management of leech infestations among ethnic groups in Assam is discussed. Data collection included ethnobotanical methods of group discussions and semi-structured interview. A total of 13 medicinal plants and 08 non-plant products are used by ethnic groups for management of leech infestation. Mikania scandens and Chromolaena odorata while among non-plant sources common salt and kerosene are the most extensively used ethnomedicines against leech infestation. In rare cases of intraperitoneal leech bites, Cucumis sativus or raw duck blood is taken to expel the leech. Ethnobotanical studies followed by chemical evaluation of locally used anti-leech plants can provide valuable clues about the bioactive compounds and prioritize species for further pharmacological investigation.&lt;/p&gt;

A Comparative Effectiveness Study of Bone Density Changes in Women Over 40 Following Three Bone Health Plans Containing Variations of the Same Novel Plant-sourced Calcium

The US Surgeon General's Report on Bone Health suggests America's bone-health is in jeopardy and issued a "call to action" to develop bone-health plans incorporating components of (1) improved nutrition, (2) increased health literacy, and (3) increased physical activity. To conduct a Comparative Effectiveness Research (CER) study comparing changes in bone mineral density in healthy women over-40 with above-average compliance when following one of three bone health Plans incorporating the SG's three components. Using an open-label sequential design, 414 females over 40 years of age were tested, 176 of whom agreed to participate and follow one of three different bone-health programs. One Plan contained a bone-health supplement with 1,000 IUs of vitamin D(3 )and 750 mg of a plant-sourced form of calcium for one year. The other two Plans contained the same plant form of calcium, but with differing amounts of vitamin D(3) and other added bone health ingredients along with components designed to increase physical activity and health literacy. Each group completed the same baseline and ending DXA bone density scans, 43-chemistry blood test panels, and 84-item Quality of Life Inventory (QOL). Changes for all subjects were annualized as percent change in BMD from baseline. Using self-reports of adherence, subjects were rank-ordered and dichotomized as "compliant" or "partially compliant" based on the median rating. Comparisons were also made between the treatment groups and two theoretical age-adjusted expected groups: a non-intervention group and a group derived from a review of previously published studies on non-plant sources of calcium. There were no significant differences in baseline BMD between those who volunteered versus those who did not and between those who completed per protocol (PP) and those who were lost to attrition. Among subjects completing per protocol, there were no significant differences between the three groups on baseline measurements of BMD, weight, age, body fat and fat-free mass suggesting that the treatment groups were statistically similar at baseline. In all three treatment groups subjects with above average compliance had significantly greater increases in BMD as compared to the two expected-change reference groups. The group following the most nutritionally comprehensive Plan outperformed the other two groups. For all three groups, there were no statistically significant differences between baseline and ending blood chemistry tests or the QOL self-reports. The increases in BMD found in all three treatment groups in this CER stand in marked contrast to previous studies reporting that interventions with calcium and vitamin D(3) reduce age-related losses of BMD, but do not increase BMD. Increased compliance resulted in increased BMD levels. No adverse effects were found in the blood chemistry tests, self-reported quality of life and daily tracking reports. The Plans tested suggest a significant improvement over the traditional calcium and vitamin D(3) standard of care.

Endophytic Bacteria Associated with Growing Shoot Tips of Banana (Musa sp.) cv. Grand Naine and the Affinity of Endophytes to the Host

A cultivation-based assessment of endophytic bacteria present in deep-seated shoot tips of banana suckers was made with a view to generate information on the associated organisms, potential endophytic contaminants in tissue-cultured bananas and to assess if the endophytes shared a beneficial relationship with the host. Plating the tissue homogenate from the central core of suckers showed colony growth on nutrient agar from just 75% and 42% of the 12 stocks during May and November, respectively (average 58%; 6 x 10(3) colony-forming units per gram), yielding diverse organisms belonging to firmicutes (Bacillus, Brevibacillus, Paenibacillus, Virgibacillus, Staphylococcus spp.), actinobacteria (Cellulomonas, Micrococcus, Corynebacterium, Kocuria spp.), alpha-proteobacteria (Paracoccus sp.), and gamma-proteobacteria (Pseudomonas, Acinetobacter spp.). Each shoot tip showed one to three different organisms and no specific organism appeared common to different sucker tips. Tissue homogenate from shoot tips including the ones that did not yield culturable bacteria displayed abundant bacterial cells during microscopic examination suggesting that a high proportion of cells were in viable-but-nonculturable state, or their cultivation requirements were not met. Direct application of cultivation-independent approach to study endophytic bacterial community using bacterial 16S ribosomal RNA universal primers resulted in high interference from chloroplast and mitochondrial genome sequences. Dislodging the bacterial cells from shoot tips that did not show cultivable bacteria and incubating the tissue crush in dilute-nutrient broth led to the activation of four organisms (Klebsiella, Agrobacterium, Pseudacidovorax spp., and an unidentified isolate). The endophytic organisms in general showed better growth at 30-37 degrees C compared with 25 degrees C, and the growth of endophytes as well as pathogenic Erwinia carotovora were promoted with the supply of host tissue extract (HTE) while that of the isolates from nonplant sources were inhibited or unaffected by HTE, suggesting an affinity or dependence of the endophytes on the host and the prospect of an HTE-based assay for discriminating the nonendophytes from endophytes.

In vitro assembly of the Tomato bushy stunt virus replicase requires the host Heat shock protein 70

To gain insights into the functions of a viral RNA replicase, we have assembled in vitro and entirely from nonplant sources, a fully functional replicase complex of Tomato bushy stunt virus (TBSV). The formation of the TBSV replicase required two purified recombinant TBSV replication proteins, which were obtained from E. coli, the viral RNA replicon, rATP, rGTP, and a yeast cell-free extract. The in vitro assembly of the replicase took place in the membraneous fraction of the yeast extract, in which the viral replicase-RNA complex became RNase- and proteinase-resistant. The assembly of the replicase complex required the heat shock protein 70 (Hsp70 = yeast Ssa1/2p) present in the soluble fraction of the yeast cell-free extract. The assembled TBSV replicase performed a complete replication cycle, synthesizing RNA complementary to the provided RNA replicon and using the complementary RNA as template to synthesize new TBSV replicon RNA.

Human health concerns with GM crops.

Biotechnology was used in the first generation of so-called 'GM' crops to provide growers with complimentary and sometimes alternative crop management solutions to pesticides. Selected host genes or genes identified from other plants or non-plant sources are modified or transferred to a crop plant. The new or altered protein expression resulting from these modifications confer on the plant a desired physiological trait, such as resistance to particular herbicides or insect pests. Second generation modifications provide traits such as enhanced nutritional or health-promoting characteristics that are of benefit to consumers. The commonly raised concerns about possible implications for human health are: inherent toxicity of the novel gene and their products, the potential to express novel antigenic proteins or alter levels of existing protein allergens, the potential for unintended effects resulting from alterations of host metabolic pathways or over expression of inherently toxic or pharmacologically active substances and the potential for nutrient composition in the new food occur differing significantly from a conventional counterpart. Foods produced using biotechnology are subjected to far greater levels of scrutiny than foods produced by traditional plant breeding techniques. The accepted analytical, nutritional and toxicological methods employed to support this scrutiny and to assess and assure that a 'GM' food is a safe and nutritious as its 'non-GM' counterpart are discussed. The challenges associated with identifying unintended effects in whole GM foods and the promise new (proteomics/genomic) technologies offer opposite traditional toxicity testing paradigms are appraised.

Dual intracellular localization and targeting of aminoimidazole ribonucleotide synthetase in cowpea.

De novo purine biosynthesis is localized to both mitochondria and plastids isolated from Bradyrhizobium sp.-infected cells of cowpea (Vigna unguiculata L. Walp) nodules, but several of the pathway enzymes, including aminoimidazole ribonucleotide synthetase (AIRS [EC 6.3.3.1], encoded by Vupur5), are encoded by single genes. Immunolocalization confirmed the presence of AIRS protein in both organelles. Enzymatically active AIRS was purified separately from nodule mitochondria and plastids. N-terminal sequencing showed that these two isoforms matched the Vupur5 cDNA sequence but were processed at different sites following import; the mitochondrial isoform was five amino acids longer than the plastid isoform. Electrospray tandem mass spectrometry of a trypsin digest of mitochondrial AIRS identified two internal peptides identical with the amino acid sequence deduced from Vupur5 cDNA. Western blots of proteins from mitochondria and plastids isolated from root tips showed a single AIRS protein present at low levels in both organelles. (35)S-AIRS protein translated from a Vupur5 cDNA was imported into isolated pea (Pisum sativum) leaf chloroplasts in vitro by an ATP-dependent process but not into import-competent mitochondria from several plant and non-plant sources. Components of the mature protein are likely to be important for import because the N-terminal targeting sequence was unable to target green fluorescent protein to either chloroplasts or mitochondria in Arabidopsis leaves. The data confirm localization of the protein translated from the AIRS gene in cowpea to both plastids and mitochondria and that it is cotargeted to both organelles, but the mechanism underlying import into mitochondria has features that are yet to be identified.

A constitutive gene expression system derived from the tCUP cryptic promoter elements.

A limited number of constitutive promoters have been used to direct transgene expression in plants and they are often derived from non-plant sources. Here, we describe novel gene-regulatory elements which are associated with a cryptic constitutive promoter from tobacco, tCUP, and modifications that were made to create a strong gene-expression system that is effective across all living cell types from a wide range of plant species, including several important crops ( Arabidopsis, canola, flax, alfalfa, tobacco). The tCUP 5' untranslated region was mutated to eliminate translational interference by upstream ATGs, and the influence of the Kozak consensus sequence on the levels of a beta-glucuronidase (GUS) reporter gene activity was demonstrated. These modifications resulted in expression that was greatly enhanced in all organs. A TATA consensus sequence was added to the core promoter to complement an existing Initiator (Inr) sequence. Although this addition was known to elevate core promoter activity by 3-fold the additive effect on the overall gene-expression system was marginal in all of the transgenic plants tested. Two transcriptional enhancers were identified and the region containing them were oligomerized, yielding a significant increase in marker gene-expression in some but not all plant species. In general, the enhanced tCUP gene-expression system generated levels of GUS activity which exceeded that of the 35S promoter in most plant species and the elevation in activity occurred uniformly among the various plant organs. The potential benefit of cryptic elements for the construction of gene-expression systems for crop species is discussed

Beta-mannosidase (EC 3.2.1.25) activity during and following germination of tomato (Lycopersicon esculentum Mill.) seeds. Purification, cloning and characterization.

Beta-mannosidase, a high-salt-soluble enzyme, increases in activity in seeds of tomato prior to the completion of germination. This increase occurs in both the lateral and micropylar endosperm and becomes more evident during post-germinative seedling growth. The beta-mannosidase activity profile is similar to that of endo beta-mannanase although it is the first to increase in the lateral endosperm. Tomato seed beta-mannosidase was purified to homogeneity and its cDNA (LeMside1) obtained by 3'-RACE PCR using oligonucleotide sequences based on four peptide sequences obtained from the purified enzyme. The derived amino acid sequence of the tomato beta-mannosidase shows the enzyme is a member of the Glycosyl Hydrolases Family 1 (GHF1) but has a very low sequence identity with that of beta-mannosidases from non-plant sources; no other plant sequence for the enzyme is known. There appears to be only one gene encoding beta-mannosidase in tomato, the sequence of which has been determined (LeMSide2). Its expression occurs first in the micropylar endosperm, and then declines after germination. This is followed by an increase in its expression in the lateral endosperm, which precedes that of the gene for endo beta-mannanase. Expression of the beta-mannosidase gene increases appreciably in the growing seedling embryo. With this report, the cloning of all three of the enzymes involved in galactomannan mobilization (endo beta-mannanase, alpha-galactosidase and beta-mannosidase) in tomato seeds has now been achieved.

Genetic engineering of plants to enhance resistance to fungal pathogens—a review of progress and future prospects

Recent applications of techniques in plant molecular biology and biotechnology to the study of host–pathogen interactions have resulted in the identification and cloning of numerous genes involved in the defense responses of plants following pathogen infection. These include: genes that express proteins, peptides, or antimicrobial compounds that are directly toxic to pathogens or that reduce their growth in situ; gene products that directly inhibit pathogen virulence products or enhance plant structural defense genes, that directly or indirectly activate general plant defense responses; and resistance genes involved in the hypersensitive response and in the interactions with avirulence factors. The introduction and expression of these genes, as well as of antimicrobial genes from nonplant sources, in a range of transgenic plant species have shown that the development of fungal pathogens can be significantly reduced. The extent of disease reduction varies with the strategy employed as well as with the characteristics of the fungal pathogen, and disease control has never been complete. Manipulation of salicylic acid, ethylene, and cytokinin levels in transgenic plants have provided some interesting results with regard to enhanced disease tolerance or susceptibility. The complex interactions among the expressed gene product, plant species, and fungal pathogen indicate that the response of transgenic plants cannot be readily predicted. Combinations of defense gene products have shown considerably more promise in reducing disease than single-transgene introductions. The use of tissue-specific or pathogen-inducible promoters, and the engineered expression of resistance genes, synthetic antimicrobial peptides, and elicitor molecules that induce defense responses have the potential to provide commercially useful broad-spectrum disease resistance in the not-too-distant future. The issues and challenges that will need to be addressed prior to the widespread utilization of these transgenic plants are highlighted.

Integration of the mitochondrial-processing peptidase into the cytochrome bc1 complex in plants.

The plant mitochondrial cytochrome bc1 complex, like nonplant mitochondrial complexes, consists of cytochromes b and c1, the Rieske iron-sulfur protein, two Core proteins, and five low-molecular mass subunits. However, in contrast to nonplant sources, the two Core proteins are identical to subunits of the general mitochondrial processing peptidase (MPP). The MPP is a fascinating enzyme that catalyzes the specific cleavage of the diverse presequence peptides from hundreds of the nuclear-encoded mitochondrial precursor proteins that are synthesized in the cytosol and imported into the mitochondrion. Integration of the MPP into the bc1 complex renders the bc1 complex in plants bifunctional, being involved both in electron transport and in protein processing. Despite the integration of MPP into the bc1 complex, electron transfer as well as translocation of the precursor through the import channel are independent of the protein-processing activity. Recognition of the processing site by MPP occurs via the recognition of higher-order structural elements in combination with charge and cleavage-site properties. Elucidation of the three-dimensional (3-D) structure of the mammalian cytochrome bc1 complex is highly useful for understanding of the mechanism of action of MPP.