Effect of Cadmium on the Level of Isoprenoid-Derived Phytohormones in Duckweed Wolffia arrhiza

Journal of Plant Growth Regulation - Wolffia arrhiza (L.) Horkel ex Wimm. is an aquatic plant belonging to the Lemnaceae family. It does not have leaves, stems, and roots, flowers rarely occur,...     

The larval morphology of Arrenurus nobilis Neuman, 1880 and A. robustus Koenike, 1894 (Acari: Parasitengona: Arrenuridae)

The morphology of the larval stages of Arrenurus nobilis and A. robustus is described. Particular attention is given to characters that help to distinguish the two species, and to characters defining the subgenus Arrenurus s. str. The larva of A. robustus resembles the larvae of A. papillator and A. pustulator regarding the shape of dorsal plate, excretory pore plate, coxal plate median margins ratios, and the presence of the IIITa8 seta. The shape of the excretory pore plate in A. nobilis resembles the one in Arrenurus (Megaluracarus) mediorotundatus. The shape of dorsal plate and chelicerae is similar to the ones in the Megaluracarus-species A. globator and A. tubulator. The lack of the IIITa8 seta differs from other species of the subgenus Arrenurus s. str. In the pectinate Lp2 and Mh1 setae A. nobilis resembles representatives of the subgenus Arrenurus s. str. This demonstrates the necessity of verifying the taxonomic status of A. nobilis.     

Sequence Analysis of In Vivo Defective Interfering-Like RNA of Influenza A H1N1 Pandemic Virus

Influenza virus defective interfering (DI) particles are naturally occurring noninfectious virions typically generated during in vitro serial passages in cell culture of the virus at a high multiplicity of infection. DI particles are recognized for the role they play in inhibiting viral replication and for the impact they have on the production of infectious virions. To date, influenza virus DI particles have been reported primarily as a phenomenon of cell culture and in experimentally infected embryonated chicken eggs. They have also been isolated from a respiratory infection of chickens. Using a sequencing approach, we characterize several subgenomic viral RNAs from human nasopharyngeal specimens infected with the influenza A(H1N1)pdm09 virus. The distribution of these in vivo-derived DI-like RNAs was similar to that of in vitro DIs, with the majority of the defective RNAs generated from the PB2 (segment 1) of the polymerase complex, followed by PB1 and PA. The lengths of the in vivo-derived DI-like segments also are similar to those of known in vitro DIs, and the in vivo-derived DI-like segments share internal deletions of the same segments. The presence of identical DI-like RNAs in patients linked by direct contact is compatible with transmission between them. The functional role of DI-like RNAs in natural infections remains to be established.     

The chemical synthesis and cytotoxicity of new sulfur analogues of 2-methoxy-lysophosphatidylcholine

The chemical synthesis of phosphorothioate/phosphorodithioate analogues of 2-methoxy-lysophosphatidylcholine has been described. For the preparation of new sulfur derivatives of lysophosphatidylcholine both oxathiaphospholane and dithiaphospholane approaches have been employed. Each lysophospholipid analogue was synthesized as a series of five compounds, bearing different fatty acid residues both saturated (12:0, 14:0, 16:0, 18:0) and unsaturated (18:1). The methylation of glycerol 2-hydroxyl function was applied in order to increase the stability of prepared analogues by preventing 1→2 acyl migration. The cellular toxicity of newly synthesized 2-methoxy-lysophosphatidylcholine derivatives was measured using MTT viability assay and lactate dehydrogenase release method.     

Basal metabolic rate is positively correlated with parental investment in laboratory mice

The assimilation capacity (AC) hypothesis for the evolution of endothermy predicts that the maternal basal metabolic rate (BMR) should be positively correlated with the capacity for parental investment. In this study, we provide a unique test of the AC model based on mice from a long-term selection experiment designed to produce divergent levels of BMR. By constructing experimental families with cross-fostered litters, we were able to control for the effect of the mother as well as the type of pup based on the selected lines. We found that mothers with genetically determined high levels of BMR were characterized by higher parental investment capacity, measured as the offspring growth rate. We also found higher food consumption and heavier visceral organs in the females with high BMR. These findings suggested that the high-BMR females have higher energy acquisition abilities. When the effect of the line type of a foster mother was controlled, the pup line type significantly affected the growth rate only in the first week of life, with young from the high-BMR line type growing more rapidly. Our results support the predictions of the AC model.     

In Search of Functional Advantages of Knots in Proteins

We analysed the structure of deeply knotted proteins representing three unrelated families of knotted proteins. We looked at the correlation between positions of knotted cores in these proteins and such local structural characteristics as the number of intra-chain contacts, structural stability and solvent accessibility. We observed that the knotted cores and especially their borders showed strong enrichment in the number of contacts. These regions showed also increased thermal stability, whereas their solvent accessibility was decreased. Interestingly, the active sites within these knotted proteins preferentially located in the regions with increased number of contacts that also have increased thermal stability and decreased solvent accessibility. Our results suggest that knotting of polypeptide chains provides a favourable environment for the active sites observed in knotted proteins. Some knotted proteins have homologues without a knot. Interestingly, these unknotted homologues form local entanglements that retain structural characteristics of the knotted cores.     

Laying characteristics of one- and two-year old pheasants (Phasianus colchicus, L.)

The aim ofthe study was to assess laying traits, the weight of eggs and characters ofthe laying rhythm of pheasants in the first and second years of reproduction. Pheasants (10 cockerels and 50 hens) were kept in aviaries. Daily, individual control of laying was performed beginning with the day of the first laying and ending with the last egg. The following parameters were evaluated: age at first laying, length of the laying period, number of laid eggs and the average weight of the egg in the 8th week of laying. The laying rhythm was also assessed and comprised: the number of egg clutches, the number of eggs in a clutch, the number of eggs in the longest clutch, the number of intervals, the length of intervals and the longest interval between clutches. During the first period of reproduction, in comparison with the second, pheasants laid slightly more eggs of similar average weight. The first laying period was longer than the second and was characterised by a greater number of egg clutches and greater number of intervals between clutches. The greatest number of eggs was laid in 10-egg and longer clutches, although the l-egg clutches were the most numerous. A positive correlation was found between the number of eggs and the number of clutches, the greatest number of eggs in a clutch and the number of intervals between clutches. The similar values of the reproductive characters of one- and two-year old pheasants point to the possibility of longer utilization of these birds than only for one laying period. On the other hand, the considerable variability between the experimental hens with regard to the number and the length of egg clutches, as well as the intervals between them, indicate the possibility to carry out selection taking into account traits characterising the laying rhythm.     

Air pollution distribution patterns in the San Bernardino Mountains of southern California: a 40-year perspective

Since the mid-1950s, native pines in the San Bernardino Mountains (SBM) in southern California have shown symptoms of decline. Initial studies in 1963 showed that ozone (O3) generated in the upwind Los Angeles Basin was responsible for the injury and decline of sensitive trees. Ambient O3 decreased significantly by the mid-1990s, resulting in decreased O3 injury and improved tree growth. Increased growth of trees may also be attributed to elevated atmospheric nitrogen (N) deposition. Since most of the N deposition to mixed conifer forest stands in the SBM results from dry deposition of nitric acid vapor (HNO3) and ammonia (NH3), characterization of spatial and temporal distribution of these two pollutants has become essential. Although maximum daytime O3 concentrations over last 40 years have significantly decreased (approximately 3-fold), seasonal means have been reduced much less (approximately 1.5-fold), with 2-week long means occasionally exceeding 100 ppb in the western part of the range. In the same area, significantly elevated concentrations of HNO3 and NH3, up to 17.5 and 18.5 microg/m3 as 2-week averages, respectively, have been determined. Elevated levels of O3 and increased N deposition together with long-term drought predispose the SBM forests to massive bark beetle attacks making them susceptible to catastrophic fires.     

In situ proteolysis for protein crystallization and structure determination

We tested the general applicability of in situ proteolysis to form protein crystals suitable for structure determination by adding a protease (chymotrypsin or trypsin) digestion step to crystallization trials of 55 bacterial and 14 human proteins that had proven recalcitrant to our best efforts at crystallization or structure determination. This is a work in progress; so far we determined structures of 9 bacterial proteins and the human aminoimidazole ribonucleotide synthetase (AIRS) domain.