Taxonomic notes on some freshwater planktonic Cryptophyceae based on light microscopy

The cryptomonads sampled frequently from pelagial of large freshwater bodies, lakes and ponds, but also found in littoral regions and in small water bodies covered with vegetation, are often characterized by the sigmoid (S-shaped) form of their cells. According to the quoted findings of electron microscopy it seems that these species should be incorporated into the new genus Campylomonas Hill. Because the EM characteristics have not been proved so far for all species, and the following nomenclatural combinations accomplished, the traditional classification into the genus Cryptomonas is kept here. The correct name for the largest of sigmoid cryptomonads is Cryptomonas curvataEhr. em. Penard. Contrarily, C. rostrata Troitz. em. Kisel. is to be held for later synonyms. The existence of the species C. rostratiformis Skuja remains uncertain. The smaller species of sigmoid shape, i.e. C. reflexa (Marss.) Skuja and C. marssonii Skuja, may also easily be discerned under the light microscope. From the small puddles with H₂S in water, shortened forms of both these species are documented, one of them under the published name C. anas Javorn. The pelagic assemblage of the above sigmoid cryptomonads frequently is completed by Plagioselmis nannoplanctica (Skuja) Novar., Lucas et Morr. and by P. lacustris (Pasch. et Ruttn.) Javorn. These flagellates so far are currently determined as the species of the genus RhodomonasKarsten. In addition to the EM characteristic, they differ from Rhodomonas by the absence of a true gullet (pseudopharynx) having only the ventral furrow with rows of superficial ejectosomes (similar to the genus Cryptochrysis Pascher). The ellipsoidal or ovoid cryptomonads are sampled more frequently from peat pools and small water bodies covered with vegetation than from open pelagial of lakes. An erroneous determination of them causes confusion. Because some strains are wrongly labeled, electron-microscopic characteristics are vaguely determined species. For example, some EM features of Cryptomonas ovata in fact belong to C. pyrenoidifera Geitl. or to C. phaseolus Skuja. Cryptomonas ovata Ehr. em. Stein is not a collective species with a wide dimensional range of ellipsoid cells. It is a large species the typical morphology which is described here in detail. C. splendida Czosn. differs from C. ovata only by the transversal orientation of the cell. Similar to C. ovata but smaller species is C. tatrica Czosn. These species are further compared with the well-defined species C. obovata Skuja and the particularly small C. phaseolus Skuja.     

Aluminium Uptake and Translocation in Al Hyperaccumulator Rumex obtusifolius Is Affected by Low-Molecular-Weight Organic Acids Content and Soil pH

Background and Aims

High Al resistance of Rumex obtusifolius together with its ability to accumulate Al has never been studied in weakly acidic conditions (pH > 5.8) and is not sufficiently described in real soil conditions. The potential elucidation of the role of organic acids in plant can explain the Al tolerance mechanism.

Methods

We established a pot experiment with R. obtusifolius planted in slightly acidic and alkaline soils. For the manipulation of Al availability, both soils were untreated and treated by lime and superphosphate. We determined mobile Al concentrations in soils and concentrations of Al and organic acids in organs.

Results

Al availability correlated positively to the extraction of organic acids (citric acid < oxalic acid) in soils. Monovalent Al cations were the most abundant mobile Al forms with positive charge in soils. Liming and superphosphate application were ambiguous measures for changing Al mobility in soils. Elevated transport of total Al from belowground organs into leaves was recorded in both lime-treated soils and in superphosphate-treated alkaline soil as a result of sufficient amount of Ca available from soil solution as well as from superphosphate that can probably modify distribution of total Al in R. obtusifolius as a representative of “oxalate plants.” The highest concentrations of Al and organic acids were recorded in the leaves, followed by the stem and belowground organ infusions.

Conclusions

In alkaline soil, R. obtusifolius is an Al-hyperaccumulator with the highest concentrations of oxalate in leaves, of malate in stems, and of citrate in belowground organs. These organic acids form strong complexes with Al that can play a key role in internal Al tolerance but the used methods did not allow us to distinguish the proportion of total Al-organic complexes to the free organic acids.     

Panitumumab Use in Metastatic Colorectal Cancer and Patterns of KRAS Testing: Results from a Europe-Wide Physician Survey and Medical Records Review

Background

From 2008–2013, the European indication for panitumumab required that patients’ tumor KRAS exon 2 mutation status was known prior to starting treatment. To evaluate physician awareness of panitumumab prescribing information and how physicians prescribe panitumumab in patients with metastatic colorectal cancer (mCRC), two European multi-country, cross-sectional, observational studies were initiated in 2012: a physician survey and a medical records review. The first two out of three planned rounds for each study are reported.

Methods

The primary objective in the physician survey was to estimate the prevalence of KRAS testing, and in the medical records review, it was to evaluate the effect of test results on patterns of panitumumab use. The medical records review study also included a pathologists’ survey.

Results

In the physician survey, nearly all oncologists (299/301) were aware of the correct panitumumab indication and the need to test patients’ tumor KRAS status before treatment with panitumumab. Nearly all oncologists (283/301) had in the past 6 months of clinical practice administered panitumumab correctly to mCRC patients with wild-type KRAS status. In the medical records review, 97.5% of participating oncologists (77/79) conducted a KRAS test for all of their patients prior to prescribing panitumumab. Four patients (1.3%) did not have tumor KRAS mutation status tested prior to starting panitumumab treatment. Approximately one-quarter of patients (85/306) were treated with panitumumab and concurrent oxaliplatin-containing chemotherapy; of these, 83/85 had confirmed wild-type KRAS status prior to starting panitumumab treatment. All 56 referred laboratories that participated used a Conformité Européenne-marked or otherwise validated KRAS detection method, and nearly all (55/56) participated in a quality assurance scheme.

Conclusions

There was a high level of knowledge amongst oncologists around panitumumab prescribing information and the need to test and confirm patients’ tumors as being wild-type KRAS prior to treatment with panitumumab, with or without concurrent oxaliplatin-containing therapy.     

CD133 Expression Is Not Synonymous to Immunoreactivity for AC133 and Fluctuates throughout the Cell Cycle in Glioma Stem-Like Cells

A transmembrane protein CD133 has been implicated as a marker of stem-like glioma cells and predictor for therapeutic response in malignant brain tumours. CD133 expression is commonly evaluated by using antibodies specific for the AC133 epitope located in one of the extracellular domains of membrane-bound CD133. There is conflicting evidence regarding the significance of the AC133 epitope as a marker for identifying stem-like glioma cells and predicting the degree of malignancy in glioma cells. The reasons for discrepant results between different studies addressing the role of CD133/AC133 in gliomas are unclear. A possible source for controversies about CD133/AC133 is the widespread assumption that expression patterns of the AC133 epitope reflect linearly those of the CD133 protein. Consequently, the readouts from AC133 assessments are often interpreted in terms of the CD133 protein. The purpose of this study is to determine whether and to what extent do the readouts obtained with anti-AC133 antibody correspond to the level of CD133 protein expressed in stem-like glioma cells. Our study reveals for the first time that CD133 expressed on the surface of glioma cells is poorly immunoreactive for AC133. Furthermore, we provide evidence that the level of CD133 occupancy on the surface of glioma cells fluctuates during the cell cycle. Our results offer a new explanation for numerous inconsistencies regarding the biological and clinical significance of CD133/AC133 in human gliomas and call for caution in interpreting the lack or presence of AC133 epitope in glioma cells.     

Melatonin administered during the fetal stage affects circadian clock in the suprachiasmatic nucleus but not in the liver

The mammalian circadian system develops gradually during ontogenesis, and after birth, the system is already set to a phase of the mothers. The role of maternal melatonin in the entrainment of fetal circadian clocks has been suggested, but direct evidence is lacking. In our study, intact or pinealectomized pregnant rats were exposed to constant light (LL) throughout pregnancy to suppress the endogenous melatonin and behavioral rhythms. During the last 5 days of gestation, the rats were injected with melatonin or vehicle or were left untreated. After delivery, daily expression profiles of c‐fos and Avp in the suprachiasmatic nuclei (SCN), and Per1, Per2, Rev‐erbα, and Bmal1 in the liver were measured in 1‐day‐old pups. Due to the LL exposure, no gene expression rhythms were detected in the SCN of untreated pregnant rats or in the SCN and liver of the pups. The administration of melatonin to pregnant rats entrained the pups' gene expression profiles in the SCN, but not in the liver. Melatonin did not affect the maternal behavior during pregnancy. Vehicle injections also synchronized the gene expression in the SCN but not in the liver. Melatonin and vehicle entrained the gene expression profiles to different phases, demonstrating that the effect of melatonin was apparently not due to the treatment procedure per se. The data demonstrate that in pregnant rats with suppressed endogenous melatonin levels, pharmacological doses of melatonin affect the fetal clock in the SCN but not in the liver. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 75: 131–144, 2015     

Photobleaching and phototoxicity of KillerRed in tumor spheroids induced by continuous wave and pulsed laser illumination

The purpose of this study was to evaluate photobleaching of the genetically encoded photosensitizer KillerRed in tumor spheroids upon pulsed and continuous wave (CW) laser irradiation and to analyze the mechanisms of cancer cell death after the treatment. We observed the light‐dose dependent mechanism of KillerRed photobleaching over a wide range of fluence rates. Loss of fluorescence was limited to 80% at light doses of 150 J/cm² and more. Based on the bleaching curves, six PDT regimes were applied for irradiation using CW and pulsed regimes at a power density of 160 mW/cm² and light doses of 140 J/cm², 170 J/cm² and 200 J/cm². Irradiation of KillerRed‐expressing spheroids in the pulsed mode (pulse duration 15 ns, pulse repetition rate 10 Hz) induced predominantly apoptotic cell death, while in the case of CW mode the cancer cells underwent necrosis. In general, these results improve our understanding of photobleaching mechanisms in GFP‐like proteins and show the importance of appropriate selection of treatment mode for PDT with KillerRed.

Representative fluorescence image of two KillerRed‐expressing spheroids before and immediately after CW irradiation.