Complete DNA sequences of the plastid genomes of two parasitic flowering plant species, Cuscuta reflexa and Cuscuta gronovii

<p>Abstract</p> <p>Background</p> <p>The holoparasitic plant genus <it>Cuscuta </it>comprises species with photosynthetic capacity and functional chloroplasts as well as achlorophyllous and intermediate forms with restricted photosynthetic activity and degenerated chloroplasts. Previous data indicated significant differences with respect to the plastid genome coding capacity in different <it>Cuscuta </it>species that could correlate with their photosynthetic activity. In order to shed light on the molecular changes accompanying the parasitic lifestyle, we sequenced the plastid chromosomes of the two species <it>Cuscuta reflexa </it>and <it>Cuscuta gronovii</it>. Both species are capable of performing photosynthesis, albeit with varying efficiencies. Together with the plastid genome of <it>Epifagus virginiana</it>, an achlorophyllous parasitic plant whose plastid genome has been sequenced, these species represent a series of progression towards total dependency on the host plant, ranging from reduced levels of photosynthesis in <it>C. reflexa </it>to a restricted photosynthetic activity and degenerated chloroplasts in <it>C. gronovii </it>to an achlorophyllous state in <it>E. virginiana</it>.</p> <p>Results</p> <p>The newly sequenced plastid genomes of <it>C. reflexa </it>and <it>C. gronovii </it>reveal that the chromosome structures are generally very similar to that of non-parasitic plants, although a number of species-specific insertions, deletions (indels) and sequence inversions were identified. However, we observed a gradual adaptation of the plastid genome to the different degrees of parasitism. The changes are particularly evident in <it>C. gronovii </it>and include (a) the parallel losses of genes for the subunits of the plastid-encoded RNA polymerase and the corresponding promoters from the plastid genome, (b) the first documented loss of the gene for a putative splicing factor, MatK, from the plastid genome and (c) a significant reduction of RNA editing.</p> <p>Conclusion</p> <p>Overall, the comparative genomic analysis of plastid DNA from parasitic plants indicates a bias towards a simplification of the plastid gene expression machinery as a consequence of an increasing dependency on the host plant. A tentative assignment of the successive events in the adaptation of the plastid genomes to parasitism can be inferred from the current data set. This includes (1) a loss of non-coding regions in photosynthetic <it>Cuscuta </it>species that has resulted in a condensation of the plastid genome, (2) the simplification of plastid gene expression in species with largely impaired photosynthetic capacity and (3) the deletion of a significant part of the genetic information, including the information for the photosynthetic apparatus, in non-photosynthetic parasitic plants.</p

Verslag andijvierassenproef onder staand glas, 1956-1957

<p><b>Copyright information:</b></p><p>Taken from "Complete DNA sequences of the plastid genomes of two parasitic flowering plant species, and "</p><p>http://www.biomedcentral.com/1471-2229/7/45</p><p>BMC Plant Biology 2007;7():45-45.</p><p>Published online 22 Aug 2007</p><p>PMCID:PMC2089061.</p><p></p> for partial editing sites two chromatograms are shown in photosynthetic active tissue (top) and in pale tissue (bottom)

CAM-related changes in chloroplastic metabolism of Mesembryanthemum crystallinum L.

Crassulacean acid metabolism (CAM) is an intriguing metabolic strategy to maintain photosynthesis under conditions of closed stomata. A shift from C3 photosynthesis to CAM in Mesembryanthemum crystallinum plants was induced by high salinity (0.4 M NaCl). In CAM-performing plants, the quantum efficiencies of photosystem II and I were observed to undergo distinct diurnal fluctuations that were characterized by a strong decline at the onset of the day, midday recovery, and an evening drop. The temporal recovery of both photosystems’ efficiency at midday was associated with a more rapid induction of the electron transport rate at PSII. This recovery of the photosynthetic apparatus at midday was observed to be accompanied by extreme swelling of thylakoids. Despite these fluctuations, a persistent effect of CAM was the acceptor side limitation of PSI during the day, which was accompanied by a strongly decreased level of Rubisco protein. Diurnal changes in the efficiency of photosystems were parallel to corresponding changes in the levels of mRNAs for proteins of PSII and PSI reaction centers and for rbcL, reaching a maximum in CAM plants at midday. This might reflect a high demand for new protein synthesis at this time of the day. Hybridization of run-on transcripts with specific probes for plastid genes of M. crystallinum revealed that the changes in plastidic mRNA levels were regulated at the level of transcription

The impact of chemical compounds contained in a diet on the development and prevention of urolithiasis

Urolithiasis is one of the most common diseases of the genitourinary system. The conditions associated with the development of urolithiasis show a wide variety, among which dietary behaviour is of great importance and is nowadays becoming increasingly important in the development of kidney stones. The aim of this study was to review the literature about the impact of chemical compounds contained in a diet on the development and prevention of urolithiasis. Factors impeding the proper absorption of calcium include phosphates, fatty acids, sulphates, citrates, oxalates, while the factor that stimulates the absorption of calcium in the intestines is the active form of vitamin D3. In this regard, one should consider the amount of calcium, sodium, potassium, animal protein and simple carbohydrates consumed in a diet, as well as dietary habits regarding caffeine and alcohol. Also significant is the fact that a poorly balanced diet may condition hypercalciuria. In the case of excessive consumption of other compounds, such as simple carbohydrates and ethyl alcohol, increased urinary calcium excretion is observed, caused by disturbances in the tubular reabsorption of calcium and magnesium in nephrons. Nowadays, prophylaxis is gaining importance in the light of the growing number of cases of urolithiasis worldwide. A well-designed diet is a crucial element, affecting both the formation of deposits and treatment, hence sound knowledge of the principles of proper nutrition can significantly reduce the risk of the recurrence of renal colic. The most common cause of urolithiasis are nutritional errors, and the onset of treatment is associated with a change in dietary habits. The general nutritional recommendations for urolithiasis should be adapted to the type of urinary stones deposit and an individual patient’s comorbidities. A tailored approach to combating the disease is required

Assessment of the impact of sodium and potassium metabolism in women undergoing hysteroscopy due to pathological uterine bleeding

Monitoring the water and electrolyte balance is an integral part of diagnostics and designing an effective therapy of many diseases. Sodium and potassium play a crucial role in the diagnosis of water and electrolyte disorders. The study was conducted to demonstrate the relationship between the occurrence of electrolyte disturbances in women undergoing hysteroscopy due to pathological uterine bleeding. Medical records of 543 patients aged 21-88 (52.8±11.8 years) hospitalized in the Gynecology and Obstetrics Department of the Provincial Specialist Hospital in Biała Podlaska, who underwent hysteroscopic diagnostics due to pathological bleeding from the uterus were collected. 212 women (39.04%) were diagnosed with pathological bleeding from the uterus, 147 women (27.07%) had endomentrial hyperplasia, 104 women (19.15%) were diagnosed with an endometrial polyp, 62 women (11.42%) suffered from heavy menstruations and 18 women (3.3%) had uterine fibroids. The sodium and potassium concentrations were measured using an automated Cobas® 8000 analyzer (Roche). The average concentration of sodium in the serum was 139.84±2.13 mmol L-1 (χ 2 = 35.079; P<0.001), and the average potassium concentration was 4.44±0.37 mmol L-1 (χ 2 = 36.019; P<0.001). Higher values for sodium were recorded in the group of patients with adenomyosis (140.41±2.27 mmol L-1) and patients with uterine fibroids (140.11±1.94) mmol L-1). Statistically significant differences were found in mean sodium concentration values depending on the causes of patients’ hospitalization (H=33.914; P<0.001), and the biggest differences were between patients with ovulation disorders and patients with adenomyosis: 138.86±0.21 mmol L-1 vs. 140.41±2.27 mmol L-1 (Z=5.169; P<0.001). It seems important add measurements of sodium and potassium concentrations to the profile of tests performed in the diagnosis of gynaecological patients referred for hysteroscopy for the reasons presented in the study in order to reduce the risk of complications associated with the loss of these elements