Evaluation of old Carpathian apple cultivars as genetic resources of resistance to fire blight (Erwinia amylovora)

In the interests of re-diversifying cultivar use in apple, one of the most important breeding aims, apart from using local cultivars in breeding, is to improve resistance to fire blight (FB). At the Corvinus University of Budapest, the investigation of Hungarian cultivars found in the Carpathian Basin as genetic resources is a major part of the apple breeding program aimed at multiple resistance. The present study, initiated in the early 2000s, evaluates the FB resistance of 31 apple cultivars. Examination of the damage to shoots and flowers, and of the correlation between them, was carried out after artificial inoculation. Two dominant SCAR markers and one SSR marker were used for the genetic analysis of the cultivars giving the best results in phenotypic analysis, in order to detect quantitative trait locus alleles coding for FB resistance. Based on the results of several years of inoculation tests, the assayed cultivars exhibited a wide range of susceptibility levels on the basis of shoot necrosis and in terms of flower damage. A positive correlation (R = 0.058, p = 0.04) was demonstrated between the susceptibility found for the two plant organs. The cultivars Szabadkai szercsika and Sikulai, which gave outstanding results both in the flower and shoot tests and in the genetic analysis, could be suitable genetic resources for resistance breeding programmes. The present work confirmed the complex polygenic nature of FB resistance and the need to identify further markers in addition to those found on linkage group (LG) 3 and LG 7.     

Alien aquatic vascular plants in Hungary (Pannonian ecoregion): Historical aspects,data set and trends

Estimating the extent of biological invasions is critical in predicting the effect of exotic species. We investigated the occurrence and number of alien freshwater plants and give information on the composition of alien aquatic flora, their trend in time, invasion pathway, and their invasive character.     

Chromatin folding in human spermatozoa. I. Dynamics of chromatin remodelling in differentiating human spermatids

Changes in chromatin structure at different stages of differentiation of human spermatids were studied. It was shown that, in nuclei of early spermatids, chromatin is loosely packed and its structural element is an 8-nm fiber. This “elementary” fiber is predominant at the initial stages of differentiation; in the course of maturation, it is replaced by globular elements approximately 60 nm in diameter. In intermediate spermatids, these globules start to condense into fibrillar aggregates and reduce their diameter to 30–40 nm. At all stages of spermatid maturation, except the final stages, these globules are convergence centers for elementary fibers. This remodelling process is vectored and directed from the apical (acrosomal) to the basal pole of the nucleus. In mature spermatids, the elementary 8-nm fibers are almost absent and the major components are 40-nm fibrillar aggregates. The nuclei of mature spermatids are structurally identical with the nuclei of spermatozoa with the so-called “immature chromatin,” which are commonly found in a low proportion in sperm samples from healthy donors and may prevail over the normal cells in spermiogenetic disorders. The cause of this differentiation blockade remains unknown. Possibly, the formation of intermolecular bonds between protamines, which are required for the final stages of chromatin condensation, is blocked in a part of spermatids. The results of this study are discussed in comparison with the known models of nucleoprotamine chromatin organization in human spermatozoa.     

Down-regulation of antioxidative capacity in a transgenic tobacco which fails to develop acquired resistance to necrotization caused by TMV

Antioxidant status was assayed in leaves of two local lesion hosts of tobacco mosaic virus (TMV), namely in wild-type Xanthi-nc tobacco and in NahG transgenic tobacco, the latter of which is not able to accumulate salicylic acid (SA) and therefore is unable to develop systemic acquired resistance (SAR). Activities of several enzymes related to antioxidative defense, and the levels of glutathione, chlorogenic acid and rutin were studied. The majority of antioxidant enzymes were less active in uninfected NahG tobacco than in Xanthi-nc. Furthermore, important enzymatic and non-enzymatic antioxidants were down-regulated in TMV-infected NahG plants, as compared to Xanthi-nc. Correspondingly, SA pretreatment primed the leaves for stronger induction of antioxidants in infected Xanthi-nc, but not in NahG tobaccos. The antioxidant status of NahG tobacco even decreased after an attempted induction of SAR, while the antioxidative level increased in Xanthi-nc leaves in which the SAR was successfully induced. After infection, a greater accumulation of superoxide and H 2 O 2 , and a more intensive necrotization was positively correlated with the reduced capability of NahG leaf tissue to detoxify reactive oxygen species.     

In vitro microspore selection in maize anther culture with oxidative-stress stimulators

Summary. In order to produce doubled-haploid maize plants tolerant of oxidative stress, in vitro microspore selection was carried out in anther culture with reactive oxygen species (ROS) progenitors such as paraquat, menadione, tert-butylhydroperoxide (t-BHP), and methionine combined with riboflavin. All the ROS progenitors reduced the anther induction, the formation of microspore-derived structures, and their regeneration potential. Abnormal cell divisions and progeny cell degradation could be observed during the development of microspores treated with ROS progenitors. Menadione and t-BHP influenced the microspore developmental pathway, as menadione induced the formation of embryoids, while t-BHP increased the proportion of calli in the microspore-derived structures. As the result of in vitro selection, 15, 10, 10, and 3 fertile doubled-haploid plants were obtained in cultures treated with paraquat, t-BHP, methionine combined with riboflavin, and menadione, respectively. Correspondence and reprints: Agricultural Research Institute, Hungarian Academy of Sciences, Brunszvik utca 2, 2462 Martonvásár, Hungary.     

Nocistatin and nociceptin given centrally induce opioid-mediated gastric mucosal protection

Nociceptin (N/OFQ) and nocistatin (NST) are two endogenous neuropeptides derived from the same precursor protein, preproN/OFQ. The aim of the present work was to study the effect of NST on the ethanol-induced mucosal damage compared with that of N/OFQ following intracerebroventricular (i.c.v.) administration in the rat and to analyze the mechanism of the gastroprotective action. It was found that both NST and N/OFQ reduced the mucosal lesions in the same dose range (0.2–1 nmol i.c.v.), but in higher doses (2–5 nmol i.c.v.) the gastroprotective effect of both peptides was highly diminished. The gastroprotective effect of N/OFQ (1 nmol), but not that of NST (1 nmol), was reduced by the selective nociceptin receptor antagonist J-113397 (69 nmol i.c.v.). Similarly, decrease of the gastroprotective effect was observed after the combination of NST (1 nmol) with N/OFQ (0.6 or 1 nmol). However, addition of the gastroprotective effects was observed, when lower dose (0.2 nmol) of NST was given prior to N/OFQ (0.6 nmol). The gastroprotective effect of both N/OFQ and NST was antagonized by naloxone (27 nmol), β-funaltrexamine (20 nmol), naltrindole (5 nmol) and norbinaltorphimine (14 nmol), the μ-, δ- and κ-opioid receptor antagonists, respectively, given i.c.v. The mucosal protection was significantly decreased after bilateral cervical vagotomy. The present findings suggest that NST similar to N/OFQ, may also induce gastric mucosal protective action initiated centrally in a vagal-dependent mechanism. Opioid component is likely to be involved in the gastroprotective effect of both NST and N/OFQ.     

Isolation and identification of sapotexanthin 5,6-epoxide and 5,8-epoxide from red mamey (Pouteria sapota)

Two new carotenoids, sapotexanthin 5,6-epoxide and sapotexanthin 5,8-epoxide, have been isolated from the ripe fruits of red mamey (Pouteria sapota). Sapotexanthin 5,6-epoxide was also prepared by partial synthesis via epoxidation of sapotexanthin, and the (5R,6S) and (5S,6R) stereoisomers were identified by high-performance liquid chromatography–electronic circular dichroism (HPLC-ECD) analysis. Spectroscopic data of the natural and semisynthetic derivatives obtained by acid-catalyzed rearrangement of cryptocapsin 5,8-epoxide stereoisomers were compared for structural elucidation.     

Internal motions and exchange processes in human ileal bile acid binding protein as studied by backbone (15)N nuclear magnetic resonance spectroscopy

Human ileal bile acid binding protein (I-BABP), a member of the family of intracellular lipid binding proteins, is thought to play a role in the enterohepatic circulation of bile salts. Previously, we have shown by stopped-flow fluorescence analysis that positive binding cooperativity exhibited by I-BABP in its interactions with glycocholate (GCA) and glycochenodeoxycholate (GCDA), the two primary bile salts in humans, is related to a slow conformational change in the protein. In this study, we used backbone (15)N relaxation nuclear magnetic resonance (NMR) techniques to obtain residue-specific information about the internal dynamics of apo I-BABP and the doubly ligated I-BABP:GCA:GCDA complex on various time scales. According to our NMR data, bile salt binding is accompanied by a slight rigidification of the (15)N-(1)H bond vectors on the picosecond to nanosecond time scale, with most pronounced changes occurring in the C-D region. In contrast to the minor effects of ligation on fast motions, relaxation dispersion NMR experiments indicate a marked difference between the two protein states on the microsecond to millisecond time scale. In the apo form, an extensive network of conformational fluctuations is detected throughout segments of the EFGHIJ β-strands and the C-D loop, which cease upon complexation. Our NMR data are in agreement with a conformational selection model we proposed earlier for I-BABP and support the hypothesis of an allosteric mechanism of ligand binding. According to the NMR measurements, the helical cap region may have a less crucial role in mediating ligand entry and release than what has been indicated for fatty acid binding proteins.     

On the Structure-Bounded Growth Processes in Plant Populations

If growing cells in plants are considered to be composed of increments (ICs) an extended version of the law of mass action can be formulated. It evidences that growth of plants runs optimal if the reaction–entropy term (entropy times the absolute temperature) matches the contact energy of ICs. Since these energies are small, thermal molecular movements facilitate via relaxation the removal of structure disturbances. Stem diameter distributions exhibit extra fluctuations likely to be caused by permanent constraints. Since the signal–response system enables in principle perfect optimization only within finite-sized cell ensembles, plants comprising relatively large cell numbers form a network of size-limited subsystems. The maximal number of these constituents depends both on genetic and environmental factors. Accounting for logistical structure–dynamics interrelations, equations can be formulated to describe the bimodal growth curves of very different plants. The reproduction of the S-bended growth curves verifies that the relaxation modes with a broad structure-controlled distribution freeze successively until finally growth is fully blocked thus bringing about “continuous solidification”.