Synergids and filiform apparatus in the sexual and apomictic dandelions from section Palustria (Taraxacum, Asteraceae)

An evolutionary trend to reduce “unnecessary costs” associated with the sexual reproduction of their amphimictic ancestors, which may result in greater reproductive success, has been observed among the obligatory apomicts. However, in the case of the female gametophyte, knowledge about this trend in apomicts is not sufficient because most of the ultrastructural studies of the female gametophyte have dealt with amphimictic angiosperms. In this paper, we tested the hypothesis that, in contrast to amphimictic plants, synergids in apomictic embryo sacs do not form a filiform apparatus. We compared the synergid structure in two dandelions from sect. Palustria: the amphimictic diploid Taraxacum tenuifolium and the apomictic tetraploid, male-sterile Taraxacum brandenburgicum. Synergids in both species possessed a filiform apparatus. In T. brandenburgicum, both synergids persisted for a long time without any degeneration, in spite of the presence of an embryo and endosperm. We propose that the persistent synergids in apomicts may play a role in the transport of nutrients to the embryo

Phytoremediation of heavy metal-contaminated sites: Eco-environmental concerns, field studies, sustainability issues and future prospects

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physico-chemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metals-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches, evaluate their efficacy to remove toxic metals from our natural environment, explore current scientific progresses, field experiences and sustainability issues and revise world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in 21st century

Najnowsze osiągnięcia w zastosowaniu grafenu w czujnikach elektronicznych

The great interest in graphene is caused by its potential for constructing various sensors exhibiting excellent parameters. The high carrier mobility and the unique band structure of graphene makes it promising especially in the field-effect transistors (GFET) applications. In this article, recent advances of the selected graphene-based sensor applications were presented and the possible directions for further investigations were pointed out.Ogromne zainteresowanie grafenem w dużej mierze związane jest z możliwością zastosowania tego materiału do budowy różnego typu sensorów charakteryzujących się doskonałymi parametrami. Bardzo duża ruchliwość nośników ładunku oraz specyficzna pasmowa struktura elektronowa grafenu sprawiają, iż wydaje się on być bardzo obiecującym materiałem, szczególnie do zastosowań w układach pomiarowych wykorzystujących czujniki o architekturze tranzystorów polowych z kanałem grafenowym (GFET). W artykule omówione zostały najnowsze osiągnięcia w dziedzinie badań nad zastosowaniem grafenu w wybranych typach czujników. Wskazano także możliwe kierunki dalszych badań, które mogłyby być realizowane w najbliższej przyszłości w Katedrze Metrologii i Systemów Informacyjnych na Wydziale Elektrotechniki i Automatyki Politechniki Gdańskiej

Effect of the pineal gland and melatonin on dopamine release from perifused hypothalamus of mature female carp during spawning and winter regression

Background. Melatonin regulates various physiological and neuroendocrinological processes that occur rhythmically, and stimulates or inhibits endocrine activity of various body glands. This acts on the hypothalamic-pituitary-gonadal axis by synchronizing animals with their reproductive cycles. The proximity of melatonin receptors and dopamine and gonadoliberin production sites has led to a hypothesis that dopamine may be a link between melatonin and hypothalamic LHRH. Melatonin may have an indirect influence on animal reproduction through dopaminergic structures of the hypothalamus, but the mechanism involved remains unknown, also in fish, for this reason, the present experiment was conducted. The aim of the study was to determine the effect of melatonin on dopamine release from hypothalamic cells of mature female carp in vitro. Materials and methods. Hypothalami were perifused with a mineral medium containing melatonin (group 1), in the presence of implanted pineal glands (group 2), and with a pure mineral medium (control). Perifusion was 180 min long and samples of the effluent perifusate were collected at 15-minute intervals. Dopamine concentration in the medium was analysed radioenzymatically. The experiment was carried out in the summer during spawning and in the winter during regression. Results. The results indicate that melatonin inhibits the release of dopamine from hypothalamic cells. This effect was only noticeable in the experiment conducted during the spawning period. Conclusion. The present findings show that melatonin may have a role in the hypothalamic control of hypophyseal activity during the spawning period of carp