Relative differentiation of skeletal elements in European corvids

Summary The study compares mensural differences between various species of European corvids in all major skeletal elements. It appears that the greatest differences are found in the bill and mandible, which may reflect adaptations to various foods and feeding methods. Substantiation of this supposition, however, calls for further studies.

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Relative Differenzierung der Skelettelemente bei europäischen Corviden

Zusammenfassung Ein morphometrischer Vergleich europäischer Corviden-Arten nach allen wichtigen Skelettmerkmalen zeigt, dass die größten Unterschiede zwischen den Arten im Ober- und Unterschnabelbau bestehen. Dies wird als Anpassungen an verschiedene Nahrung und Ernährungsmethoden erklärt. Diese Vermutung erfordert jedoch noch weitere Untersuchungen.

     

The ability of plants to secrete proteases by roots.

The aim of our study was to find out if the culture medium of aseptically cultivated seedlings exhibits proteolytic activity and if this event is universal in angiospermous plants. Seedlings of 15 agricultural and wild-living plant species were cultivated for 14days without any addition of nutrients. Our studies showed that roots of higher plants could secrete proteases and that levels of proteolytic activity in the culture medium of individual species (and cultivars of the same species) could be significantly different. The differences between quantities of the secreted proteases were connected neither with the fresh weight of the growing seedlings nor with the surface of the root system. No proteins were required to induce secretion of proteases. The culture medium of a few studied species (Allium porrum, Zea mays, Helianthus annuus) showed the highest proteolytic activity at pH 7. Studies of the influence of standard protease inhibitors showed that examined proteases belong to the cysteine protease family. The results suggest that the apical parts of roots exuded proteases more intensively than mature parts. Our studies suggest that some plant species could develop a strategy to actively increase the level of free amino acids in the soil solution as a source of N. Our results may contribute to studying plant N nutrition in natural ecosystems and to increasing yield after organic fertilization of agricultural species.     

Hyperthermic modification of bleomycin--DNA interaction detected by electron spin resonance

Electron spin resonance spectra of DNA labeled with each of four spin-labeling compounds have been studied to detect interaction between the antibiotic bleomycin and DNA. Only one of these labels, compound IV, resulted in a modified spectrum when bound to DNA and the latter was subjected to bleomycin. This property has been used to monitor DNA-bleomycin interactions under physiological and hyperthermic conditions. Bleomycin produced an increase in rotational correlation time of the residue bound to DNA at 37 degrees C and a significantly higher increase at 43 degrees C. Some effect was still detected with bleomycin at 37 degrees C after preheating at 43 degrees C. Parallel studies have revealed enhanced binding of 59Fe-bleomycin to DNA during and after hyperthermic treatment.     

Influence of the type of imaging on the delineation process during the treatment planning

AimThe aim of this study was to compare the intra- and interobserver contouring variability for structures with density of organ at risk in two types of tomography: kilovoltage computed tomography (KVCT) versus megavoltage computed tomography (MVCT). The intra- and interobserver differences were examined on both types of tomography for structures which simulate human tissue or organs.Materials and methodsSix structures with density of the liver, bone, trachea, lung, soft tissue and muscle were created and used. For the measurements, the special water phantom with all structures was designed. To evaluate interobserver variability, five observers delineated the structures in both types of computed tomography (CT).ResultsIntraobserver variability was in the range of 1–14% and was the largest for the liver. The observers segmented larger volumes on MVCT compared with KVCT for the trachea (79.56 ccm vs.74.91 ccm), lung (87.61 vs. 82.50), soft tissue (154.24 vs. 145.47) and muscle (164.01 vs. 157.89). For the liver (98.13 vs. 99.38) and bone (51.86 vs. 67.97), the volume on MVCT was smaller than KVCT. The statistically significant differences between observers were observed for structures with density of the liver, bone and soft tissue on KVCT and for the liver, lung and soft tissue on MVCT. For the structures with density of the trachea and muscles, there were no significant differences for both types of tomography.ConclusionsDuring the contouring process the interobserver and intraobserver contouring uncertainty was larger on MVCT, especially for structures with HU near 80, compared with KVCT.     

Epigenetic heterogeneity of developmentally important genes in human sperm: Implications for assisted reproduction outcome

The molecular basis of male infertility is poorly understood, the majority of cases remaining unsolved. The association of aberrant sperm DNA methylation patterns and compromised semen parameters suggests that disturbances in male germline epigenetic reprogramming contribute to this problem. So far there are only few data on the epigenetic heterogeneity of sperm within a given sample and how to select the best sperm for successful infertility treatment. Limiting dilution bisulfite sequencing of small pools of sperm from fertile donors did not reveal significant differences in the occurrence of abnormal methylation imprints between sperm with and without morphological abnormalities. Intracytoplasmic morphologically selected sperm injection was not associated with an improved epigenetic quality, compared to standard intracytoplasmatic sperm injection. Deep bisulfite sequencing (DBS) of 2 imprinted and 2 pluripotency genes in sperm from men attending a fertility center showed that in both samples with normozoospermia and oligoasthenoteratozoospermia (OAT) the vast majority of sperm alleles was normally (de)methylated and the percentage of epimutations (allele methylation errors) was generally low (<1%). However, DBS allowed one to identify and quantify these rare epimutations with high accuracy. Sperm samples not leading to a pregnancy, in particular in the OAT group, had significantly more epimutations in the paternally methylated GTL2 gene than samples leading to a live birth. All 13 normozoospermic and 13 OAT samples leading to a child had <1% GTL2 epimutations, whereas one (7%) of 14 normozoospermic and 7 (50%) of 14 OAT samples without pregnancy displayed 1–14% GTL2 epimutations.     

Protection of yeast lacking the Ure2 protein against the toxicity of heavy metals and hydroperoxides by antioxidants

The aim of this study was to examine the protection of the yeast lacking the “antioxidant-like” prion precursor protein (Ure2p), by antioxidants and to elucidate how modification of redox homeostasis affects toxicity of agents inducing oxidative stress in the Δure2 cells. We found a diverse ability of a range of antioxidants to ameliorate the hypersensitivity of the Δure2 disruptant to oxidants and heavy metal ions. Glutathione and then ascorbate were the most effective antioxidants; Tempol, Trolox and melatonin were much less effective or even hampered the growth of the Δure2 cells exposed to tested agents. The intracellular level of ROS was augmented in the Δure2 mutant under normal growth conditions (1.7-fold), and after treatment with H₂O₂ (2.3-fold) and Cd(II) (2.8-fold), with respect to its wild-type counterpart. Glutathione was unable to prevent the increase in ROS production caused by CdCl₂. The Δure2 disruptant was also hypersensitive to heat shock, like mutants lacking glutathione S-transferases.     

Dietary Nisin Modulates the Gastrointestinal Microbial Ecology and Enhances Growth Performance of the Broiler Chickens

Due to antimicrobial properties, nisin is one of the most commonly used and investigated bacteriocins for food preservation. Surprisingly, nisin has had limited use in animal feed as well as there are only few reports on its influence on microbial ecology of the gastrointestinal tract (GIT). The present study therefore aimed at investigating effects of dietary nisin on broiler chicken GIT microbial ecology and performance in comparison to salinomycin, the widely used ionophore coccidiostat. In total, 720 one-day-old male Ross 308 chicks were randomly distributed to six experimental groups. The positive control (PC) diet was supplemented with salinomycin (60 mg/kg). The nisin (NI) diets were supplemented with increasing levels (100, 300, 900 and 2700 IU nisin/g, respectively) of the bacteriocin. The negative control (NC) diet contained no additives. At slaughter (35 days of age), activity of specific bacterial enzymes (α- and β-glucosidases, α-galactosidases and β-glucuronidase) in crop, ileum and caeca were significantly higher (P<0.05) in the NC group, and nisin supplementation decreased the enzyme activities to levels observed for the PC group. A similar inhibitory influence on bacterial activity was reflected in the levels of short-chain fatty acids (SCFA) and putrefactive SCFA (PSCFA) in digesta from crop and ileum; no effect was observed in caeca. Counts of Bacteroides and Enterobacteriacae in ileum digesta were significantly (P<0.001) decreased by nisin and salinomycin, but no effects were observed on the counts of Clostridium perfringens, Lactobacillus/Enterococcus and total bacteria. Like salinomycin, nisin supplementation improved broiler growth performance in a dose-dependent manner; compared to the NC group, the body weight gain of the NI₉₀₀ and NI₂₇₀₀ groups was improved by 4.7 and 8.7%, respectively. Our findings suggest that dietary nisin exerts a mode of action similar to salinomycin and could be considered as a dietary supplement for broiler chickens.     

The optimal eukaryotic signal for translation initiation from non-AUG codons,present upstream of bacteriophage lambda P cistron,is inactive in Escherichia coli

Expression of the replication genes of bacteriophage lambda, O and P, is believed to be translationally coupled. However, it was previously noted that, under conditions of amino acid starvation, when O is not synthesized, P continues to be expressed at a relatively high level. The results presented in this report, contrary to the previously presented hypothesis, suggest that an AGACUGGAU sequence (an optimal context for translation initiation from non-AUG codons in eukaryotes, and present upstream the P cistron) is inactive in Escherichia coli. Comparative sequence analysis confirms that such a signal is unlikely to be important for P synthesis. Instead, a weak Shine-Dalgarno sequence may be present upstream the P cistron, and be active in the absence of O gene expression.     

Heat tolerance variation reveals vulnerability of tropical herbivore–parasitoid interactions to climate change

Assessing the heat tolerance (CTmax) of organisms is central to understand the impact of climate change on biodiversity. While both environment and evolutionary history affect CTmax, it remains unclear how these factors and their interplay influence ecological interactions, communities and ecosystems under climate change. We collected and reared caterpillars and parasitoids from canopy and ground layers in different seasons in a tropical rainforest. We tested the CTmax and Thermal Safety Margins (TSM) of these food webs with implications for how species interactions could shift under climate change. We identified strong influence of phylogeny in herbivore–parasitoid community heat tolerance. The TSM of all insects were narrower in the canopy and parasitoids had lower heat tolerance compared to their hosts. Our CTmax-based simulation showed higher herbivore–parasitoid food web instability under climate change than previously assumed, highlighting the vulnerability of parasitoids and related herbivore control in tropical rainforests, particularly in the forest canopy.