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

An attempt at assessment of possibilities for utilization of sludge produced during water clarification for phosphorus precipitation in municipal wastewater treatment plants

Przedstawiono wyniki badań laboratoryjnych mających na celu ocenę możliwości zagospodarowania osadów powstających w zakładach wodociągowych w oczyszczalniach ścieków komunalnych. W tym celu wykonano analizę składu osadów pochodzących z układów oczyszczania wód powierzchniowych w Krakowie, z uwzględnieniem specyfiki osadów pokoagulacyjnych i osadów z wód popłucznych. Próbki tych osadów wykorzystano w testach laboratoryjnych do strącania związków fosforu w ściekach komunalnych i przefermentowanych osadach ściekowych pochodzących z krakowskich oczyszczalni. Wyznaczone dawki badanych osadów wskazują na znacznie większe możliwości praktycznego wykorzystania osadów pokoagulacyjnych niż osadów z wód popłucznych. Uzyskane w tym zakresie rezultaty były korzystne zwłaszcza w przypadku ścieków komunalnych i wskazują na możliwość ograniczenia zużycia klasycznych koagulantów stosowanych do strącania związków fosforu. W badaniach stwierdzono także usuwanie siarczków ze ścieków. Uzyskane wyniki wskazują na celowość rozważenia możliwości wykorzystania osadów z klarowania wody zarówno w samych oczyszczalniach ścieków, jak i przez ich wprowadzenie bezpośrednio do strumienia ścieków w sieci kanalizacyjnej. Dalsze prace w tym zakresie, oprócz pogłębienia wiedzy o mechanizmach badanego procesu, powinny koncentrować się na ocenie ewentualnych negatywnych skutków związanych na przykład ze zwiększeniem masy osadów kierowanych do dalszej przeróbki, a także na ocenie aspektów ekonomicznych i eksploatacyjnych tego procesu.The results of laboratory studies aimed at an assessment of possibilities for utilization of water treatment sludge produced in municipal plants were presented. For this purpose, content analysis was performed for the sludge coming from surface water treatment systems of Krakow, taking account of post-coagulation sludge and filter backwash sludge specifics. The sludge samples were used in the laboratory tests for phosphorus precipitation in municipal sewage and digested sewage sludge from Krakow treatment plants. The amounts of sludge tested indicated much wider possibilities for management of the post-coagulation compared to the backwash sludge. The results were clearly beneficial especially in case of the municipal sludge and pointed to a possible reduction in the amount of commercial coagulants applied to phosphorus precipitation. Additionally, sulfide removal from the sludge was noted. The study results indicate that it is purposeful to consider the possibility of utilization of sludge from water clarification, both in treatment plants alone and by introducing it directly into the sludge stream in a sewer system. Further studies should, beside extending the knowledge on the mechanisms of studied processes, focus on the evaluation of potential adverse effects related to e.g. increase in the amount of sludge directed for further processing as well as on the assessment of economic and operating aspects of the process

Effect of Ozonation on the Performance of Active Carbon Filter Beds

W pracy omówiono wyniki badań przeprowadzonych na stacji pilotowej, zlokalizowanej w zakładzie oczyszczania wody "Rudawa", zaopatrującej Kraków w wodę wodociągową. Celem badań było określenie optymalnego miejsca zastosowania procesu ozonowania w ciągu technologicznym zakładu wodociągowego Rudawa. Badania przeprowadzono w dwóch układach: układ badawczy I obejmował procesy ozonowania, filtracji na złożu piaskowym i filtracji na złożu węglowym, natomiast układ badawczy II obejmował procesy filtracji na złożu piaskowym, ozonowania i filtracji na złożu węglowym. Obydwa układy zasilane były wodą po procesach koagulacji i sedymentacji w układzie technologicznym stacji Rudawa. Analiza uzyskanych wyników nie wykazała różnic pomiędzy stosowaniem procesu ozonowania w układzie przed złożami piaskowymi i przed złożami węglowymi. W obydwu wypadkach uzyskano podobną końcową skuteczność oczyszczania wody. Optymalna dawka ozonu, dla której uzyskano wysoki stopień zmniejszenia analizowanych wskaźników wahała się w zakresie 0,9÷1,1 gO3/m3. Zastosowanie ozonowania, niezależnie od przyjętego układu, pozwoliło na poprawę skuteczności oczyszczania wody w wypadku absorbancji w UV o około 20%, a w wypadku barwy o około 25%. Ponadto wykazano, że proces ozonowania prowadził do zwiększenia zawartości aldehydów w wodzie o kilkanaście procent, co może być interpretowane jako wynik rozkładu związków organicznych o złożonej budowie do związków prostszych, na przykład niskocząsteczkowych kwasów organicznych.The investigations were carried out at the pilot station of the Water Treatment Plant "Rudawa" supplying tap water to the city of Cracow. The aim of the study was to establish in which part of the treatment train the ozonation process should be included. In the experiments use was made of two systems. In one of these, ozonation was performed prior to sand filtration and active carbon filtration, while in the other one ozonation was carried out after sand filtration and was followed by filtration through an active carbon bed. Both systems were fed with water treated by coagulation and sedimentation according to the treatment train used in the Water Treatment Plant "Rudawa". The study produced the following findings: regardless of whether ozonation was conducted before the sand filter or the carbon filter the final treatment efficiencies were similar. The ozone dose yielding the highest extent of pollutant removal ranged between 0.9 and 1.1 gO3/m3. With both systems, treatment efficiency was enhanced by about 20% and about 25% for UV absorbance and color matter, respectively. The ozonation process accounted for a rise in the aldehydes content by over 10%. This may be interpreted as being due to the decomposition of organic compounds from complex into simpler structures, e.g. into low-molecular-weight organic acids

Effect of melatonin on dopamine secretion in the hypothalamus of mature female common carp, Cyprinus carpio L

Background. The work was the continuation of previous study, which indicated that melatonin influences the inhibition of hypothalamic dopamine secretion in vitro. In the presently reported study, the influence of melatonin injection into the third cerebral ventricle on the release of dopamine was tested. The aim of this study was to investigate if and how melatonin affects dopamine secretion in the hypothalamus of mature female carp. Materials and methods. The concentration of dopamine in hypothalamic tissue was determined radioenzymatically. The experimental groups were fish deprived of melatonin by pinealectomy, fish that received intraventricular injections of melatonin, fish that received intraventricular injections of physiological saline, and intact fish (control treatment). The study was carried out in the summer during spawning and in the winter when fish gonads were regressed. Results. Melatonin injection resulted in an increase in dopamine concentration in the hypothalamus, which indicates that melatonin influenced aminergic nuclei inhibiting secretion of dopamine. Dopamine probably remained unreleased in the hypothalamic tissue, whereas in pinealectomized fish the lack of melatonin influenced continuous dopamine secretion, what was shown as the low dopamine level in the hypothalamus. The results confirmed the previous study effect of melatonin in mature female carp, and point to an inhibitory effect of intraventricularly injected melatonin on the release of dopamine from the hypothalamus. This effect occurred only in the summer experiment, indicating a seasonal impact of melatonin on the dopaminergic system. Conclusion. By inhibiting the release of hypothalamic dopamine, which blocks gonadotropin secretion, melatonin has a potential stimulatory effect on the release of LH and in this way may be involved in control of reproduction in carp

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