与番茄Ps-2位点紧密连锁的AFLP分子标记的获得

含有ps-2雄性不育基因的番茄材料可通过自交获得100％的不育后代,方便地应用于番茄杂交制种。作者以来自保加利亚含有ps-2基因的不育材料CMC1ps2为母本。以优良的加工番茄92155为父本。构建了123个F2分离群体,育性表型分离比例完全符合孟德尔遗传规律,为单基因隐性遗传。采用AFLP分子标记技术,通过筛选64对AFLP引物组合,获得了与可育ps-2位点紧密连锁的3个AFLP标记（E37／M47、E38／M48及E33／M50）,它们与可育基因的遗传图距分别是6．04cM、6．04cM、6．06cM,而且位于可育基因的同一侧,位置基本相同,分别扩增出390bp、150bp、80bp的DNA片断。这3个标记的获得,可直接用于标记辅助选育。加速番茄雄性不育的转育和利用。     

Flavonoids as inhibitors of human neutrophil elastase

Elastase is a proteolytic enzyme belonging to the family of hydrolases produced by human neutrophils, monocytes, macrophages, and endothelial cells. Human neutrophil elastase is known to play multiple roles in the human body, but an increase in its activity may cause a variety of diseases. Elastase inhibitors may prevent the development of psoriasis, chronic kidney disease, respiratory disorders (including COVID-19), immune disorders, and even cancers. Among polyphenolic compounds, some flavonoids and their derivatives, which are mostly found in herbal plants, have been revealed to influence elastase release and its action on human cells. This review focuses on elastase inhibitors that have been discovered from natural sources and are biochemically characterised as flavonoids. The inhibitory activity on elastase is a characteristic of flavonoid aglycones and their glycoside and methylated, acetylated and hydroxylated derivatives. The presented analysis of structure–activity relationship (SAR) enables the determination of the chemical groups responsible for evoking an inhibitory effect on elastase. Further study especially of the in vivo efficacy and safety of the described natural compounds is of interest in order to gain better understanding of their health-promoting potential.     

Sources of Variability in a Synthetic Gene Oscillator

Synthetic gene oscillators are small, engineered genetic circuits that produce periodic variations in target protein expression. Like other gene circuits, synthetic gene oscillators are noisy and exhibit fluctuations in amplitude and period. Understanding the origins of such variability is key to building predictive models that can guide the rational design of synthetic circuits. Here, we developed a method for determining the impact of different sources of noise in genetic oscillators by measuring the variability in oscillation amplitude and correlations between sister cells. We first used a combination of microfluidic devices and time-lapse fluorescence microscopy to track oscillations in cell lineages across many generations. We found that oscillation amplitude exhibited high cell-to-cell variability, while sister cells remained strongly correlated for many minutes after cell division. To understand how such variability arises, we constructed a computational model that identified the impact of various noise sources across the lineage of an initial cell. When each source of noise was appropriately tuned the model reproduced the experimentally observed amplitude variability and correlations, and accurately predicted outcomes under novel experimental conditions. Our combination of computational modeling and time-lapse data analysis provides a general way to examine the sources of variability in dynamic gene circuits.     

Biosynthesis of thalicarpine in Thalictrum minus

Feeding experiments with ¹⁴C-labelled reticuline, protosinomenine, orientaline, their N-nor-analogues and ³H-labelled isoboldine have shown reticuline and isoboldine to be the most efficient precursors of thalicarpine in Thalictrum minus. A biosynthetic pathway for thalicarpine with reticuline and isoboldine at the benzylisoquinoline and aporphine stages respectively has been suggested. Support for this proposal has been provided by the demonstration by radioisotopic dilution that reticuline and isoboldine are minor constituents of the plant.     

Plant regeneration from suspension culture and mesophyll protoplasts of Medicago sativa L.

A system was established for achieving plant regeneration from mesophyll protoplasts and cotyledon-derived cell suspension cultures of alfalfa, Medicago sativa L. Peeled leaflets or cells from 6-day-old cell suspensions were incubated in an enzyme mixture containing 1% Driselase, 1% Rhozyme, 0.1% Cellulase and 72 gl^-1 mannitol at pH 5.8 for 2–16 h to liberate protoplasts. A complex Kao medium supported cell division and colony formation, whereas a high auxin/low cytokinin treatment on Schenk and Hildebrandt medium followed by culture on growth regulator-free Blaydes or Linsmaier and Skoog medium resulted in somatic embryo formation. Of the three varieties tested. Citation, Answer and Regen S, the latter two produced embryos from which plants could be regenerated.     

Ploidy levels in Beta vulgaris (red beet) plant organs and in vitro systems

The ploidy levels of the cells in different organs (leaves, petioles and roots) of red beet (Beta vulgaris L.) plants of different ages, as well as of different in vitro systems (transformed hairy roots, calli derived from leaves and rhizogenic calli), were investigated using flow cytometry. Two callus lines with red and yellow phenotypes, derived by mechanical separation of the morphologically heterogeneous rhizogenic callus, were also examined. All investigated samples experienced several cycles of endoreduplication. The older organs exhibited higher levels of polysomaty than the young ones. The highest degree of endoreduplication was found in old petiole tissue and the lowest in the red callus line (cycle values of 1.81 and 0.55, respectively). Interestingly, the callus derived from leaves did not exhibit a 2Cx peak, but was tetraploid, probably due to genetic instability, which may have been caused by prolonged cultivation under in vitro conditions. Red and yellow calli showed significantly lower polysomaty (cycle values of 0.55 and 0.59, respectively) than the primary rhizogenic callus (cycle value of 1.09). The DNA profiles of the two phenotypes differed, possibly reflecting differences in their metabolism.     

Alkaloids biosynthesis by <Emphasis Type="Italic">Pancratium maritimum</Emphasis> L. shoots in liquid culture

The process of alkaloid biosynthesis by Pancratium maritimum shoot culture, cultivated under submerged conditions, was investigated. Twenty-two compounds of different structural types of the Amaryllidaceae alkaloids (tyramine, narciclasine, galanthamine, haemanthamine, lycorine, pancracine, tazettine and homolycorine types) were detected in the studied samples from biomass and cultural liquid. Dominant compounds in the shoots were of tyramine, lycorine and haemanthamine types, whereas in the culture media were found mainly lycorine type compounds. Based on the multi-metabolic estimation of the alkaloid metabolism and physiological peculiarities, liquid cultures of P. maritimum shoots could be defined as prospective biological systems for producing bioactive molecules with acetylcholinesterase inhibitory and apoptotic activities.     

Regeneration systems from immature embryos of Bulgarian pea genotypes

Ten genotypes from Pisum sativum and Pisum arvense were screened for their regeneration abilities. Most of them were created through experimental mutagenesis from Bulgarian varieties and have various valuable agronomic traits. Embryonic axes from immature embryos were plated on modified Murashige and Skoog medium, containing different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-d), α-naphthaleneacetic acid (NAA) and benzyladenine (BA). Two schemes for direct and indirect organogenesis were established. Callus and shoot formation were induced on media containing 0.2 mM 2,4-d or 5 mM BA, respectively. Embryonic axes formed buds directly when plated on medium with 10 mM BA and 1 mM NAA. Organogenesis and adventitious bud formation were maintained on medium supplemented with BA and NAA. Rhizogenesis was induced on Gamborgs' B5 medium. All screened genotypes were able to regenerate plants with a high efficiency (50–100%) although some differences in their organogenetic response were observed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Kinetic studies of embryo development and nutrient utilization in an alfalfa direct somatic embryogenic system

A method for direct somatic embryogenesis in alfalfa (Medicago falcata) is described. The time course in the development phase has been followed for fresh weight, cell density, pH, sugar uptake and embryo number and type. The method of disrupting the explant material has also been shown to influence subsequent embryo formation.