Phytoplankton Composition and Abundance in Restored Maltański Reservoir under the Influence of Physico-Chemical Variables and Zooplankton Grazing Pressure

In this paper we present the effects of environmental factors and zooplankton food pressure on phytoplankton in the restored man-made Maltański Reservoir (MR). Two methods of restoration: biomanipulation and phosphorus inactivation have been applied in the reservoir. Nine taxonomical groups of phytoplankton represented in total by 183 taxa were stated there. The richest groups in respect of taxa number were green algae, cyanobacteria and diatoms. The diatoms, cryptophytes, chrysophytes, cyanobacteria, green algae and euglenophytes dominated in terms of abundance and/or biomass. There were significant changes among environmental parameters resulting from restoration measures which influenced the phytoplankton populations in the reservoir. These measures led to a decrease of phosphorus concentration due to its chemical inactivation and enhanced zooplankton grazing as a result of planktivorous fish stocking. The aim of the study is to analyse the reaction of phytoplankton to the restoration measures and, most importantly, to determine the extent to which the qualitative and quantitative composition of phytoplankton depends on variables changing under the influence of restoration in comparison with other environmental variables. We stated that application of restoration methods did cause significant changes in phytoplankton community structure. The abundance of most phytoplankton taxa was negatively correlated with large zooplankton filter feeders, and positively with zooplankton predators and concentrations of ammonium nitrogen and partly of phosphates. However, restoration was insufficient in the case of decreasing phytoplankton abundance. The effects of restoration treatments were of less importance for the abundance of phytoplankton than parameters that were independent of the restoration. This was due to the continuous inflow of large loads of nutrients from the area of the river catchment.     

A High-Fat Diet Delays Age-Related Hearing Loss Progression in C57BL/6J Mice

Objective

Age-related hearing loss (AHL), or presbycusis, is the most common sensory disorder among the elderly. We used C57BL/6J mice as an AHL model to determine a possible association between AHL and a high-fat diet (HFD).

Methods

Forty C57BL/6J mice were randomly assigned to a control or HFD group. Each group was divided into the following subgroups: 1-, 3-, 5- and 12-month groups (HFD, n = 5/subgroup; control, n = 5/subgroup). Nine CBA/N-slc mice were also used as a 12-month control (n = 5) or 12-month HFD (n = 4) group. The mice were fed a HFD or normal (control) diet throughout this study. Hearing function was evaluated at 1, 3, 5 and 12 months using auditory evoked brainstem responses (ABRs). Spiral ganglion cells (SGCs) were also counted.

Results

The elevation of ABR thresholds (at 4 and 32 kHz) at 3 and 5 months was significantly suppressed in the HFD group compared with the control groups for C57BL/6J mice. After 12 months, the elevation of ABR thresholds was significantly suppressed in the HFD group at all frequencies for C57BL/6J mice. In contrast, CBA/N-slc mice displayed opposite outcomes, as ABR thresholds at all frequencies at 12 months were significantly elevated in the HFD group compared with the control group. For the C57BL/6J mice at 12 months, SGC numbers significantly decreased in all parts of the cochleae in the control group compared with the HFD groups. In contrast, for the CBA/N-slc mice, SGC numbers significantly decreased, particularly in the upper parts of the cochleae in the HFD group compared with the control groups.

Conclusions

The elevation in ABR thresholds and SGC loss associated with aging in the HFD-fed C57BL/6J mice were significantly suppressed compared with those in the normal diet-fed mice. These results suggest that HFD delays AHL progression in the C57B/6J mice.     

Determining the Functions of HIV-1 Tat and a Second Magnesium Ion in the CDK9/Cyclin T1 Complex: A Molecular Dynamics Simulation Study

The current paradigm of cyclin-dependent kinase (CDK) regulation based on the well-established CDK2 has been recently expanded. The determination of CDK9 crystal structures suggests the requirement of an additional regulatory protein, such as human immunodeficiency virus type 1 (HIV-1) Tat, to exert its physiological functions. In most kinases, the exact number and roles of the cofactor metal ions remain unappreciated, and the repertoire has thus gained increasing attention recently. Here, molecular dynamics (MD) simulations were implemented on CDK9 to explore the functional roles of HIV-1 Tat and the second Mg²⁺ ion at site 1 (Mg₁ ²⁺). The simulations unveiled that binding of HIV-1 Tat to CDK9 not only stabilized hydrogen bonds (H-bonds) between ATP and hinge residues Asp104 and Cys106, as well as between ATP and invariant Lys48, but also facilitated the salt bridge network pertaining to the phosphorylated Thr186 at the activation loop. By contrast, these H-bonds cannot be formed in CDK9 owing to the absence of HIV-1 Tat. MD simulations further revealed that the Mg₁ ²⁺ ion, coupled with the Mg₂ ²⁺ ion, anchored to the triphosphate moiety of ATP in its catalytic competent conformation. This observation indicates the requirement of the Mg₁ ²⁺ ion for CDK9 to realize its function. Overall, the introduction of HIV-1 Tat and Mg₁ ²⁺ ion resulted in the active site architectural characteristics of phosphorylated CDK9. These data highlighted the functional roles of HIV-1 Tat and Mg₁ ²⁺ ion in the regulation of CDK9 activity, which contributes an important complementary understanding of CDK molecular underpinnings.     

Generating amplicon reads for microbial community assessment with next-generation sequencing

Marker gene amplicon sequencing is often preferred over whole genome sequencing for microbial community characterization, due to its lower cost while still enabling assessment of uncultivable organisms. This technique involves many experimental steps, each of which can be a source of errors and bias. We present an up-to-date overview of the whole experimental pipeline, from sampling to sequencing reads, and give information allowing for informed choices at each step of both planning and execution of a microbial community assessment study. When applicable, we also suggest ways of avoiding inherent pitfalls in amplicon sequencing.     

Effect of rearing Cactoblastis cactorum on an artificial diet on the behaviour of Apanteles opuntiarum

Cactoblastis cactorum's unintended arrival to Florida and its expansion in North America represent a threat to Opuntia-based agriculture and natural ecosystems in the United States and Mexico. Apanteles opuntiarum attacks C. cactorum and is a potential biocontrol agent due to its specificity, wide distribution and occurrence. Laboratory rearing methods using excised cladodes for C. cactorum as host larvae of A. opuntiarum were developed, but require a continuous supply of cactus with a risk of microorganisms compromising the rearing. Host cues —including odour of host metabolic subproducts like faeces and chemicals emitted by the attacked plant— are the most important signals that help a parasitoid locate a host. Little attention has been paid to behavioural differences of parasitoids in the presence of hosts reared on artificial diet. Thus, the aims of the present work were to determine the effect of meridic diet for C. cactorum on parasitoid behaviour and to determine whether prior experience (previous exposure to stimuli) influences the response of A. opuntiarum towards hosts. Parasitism rates were assessed using cladodes or meridic diet as larvae food source. Behavioural experiments also evaluated the effect of prior experience (larvae or frass from larvae fed on cactus or diet) on host searching, encounter and attack of different stimulus (larvae or frass from larvae fed on cactus or diet). Parasitism behaviour of A. opuntiarum was negatively affected by the use of meridic diet to feed host larvae. Presenting parasitoids with larvae rather than their frass influenced excitatory behavioural responses in terms of contact, probing and stinging in A. opuntiarum females, whereas the effect of prior experience on the behaviours was not quite consistent. For laboratory mass-rearing procedures of A. opuntiarum, we recommend previous contact of females with frass from cactus-fed larvae and a piece of cactus, which showed enhanced parasitism rates.     

Distribution of galanin-like immunoreactivity in the pig, rat and human central nervous system

The distribution of galanin-like immunoreactivity in various regions of the central nervous system was assessed in three mammalian species, pig, rat, and human, by radioimmunoassay. Galanin concentrations were highest in the hypothalamus and pituitary region. In spinal cord, there was a rostrocaudal/dorsoventral gradient with highest levels observed in the sacral dorsal horn. Serial dilutions of porcine tissue extracts diluted parallel to the porcine standard curve, while the rat and human tissue extracts did not. In all tissues examined by high pressure liquid chromatography, the principal peak of immunoreactivity coeluted with the authentic porcine galanin standard and was decreased by trypsin cleavage. These results suggest a role for galanin in the central nervous system and support species differences in the structure of galanin.     

VCIP135 deubiquitinase and its binding protein, WAC, in p97ATPase-mediated membrane fusion

Two distinct p97 membrane fusion pathways are required for Golgi biogenesis: the p97/p47 and p97/p37 pathways. VCIP135 is necessary for both pathways, while its deubiquitinating activity is required only for the p97/p47 pathway. We have now identified a novel VCIP135-binding protein, WAC. WAC localizes to the Golgi as well as the nucleus. In Golgi membranes, WAC is involved in a complex containing VCIP135 and p97. WAC directly binds to VCIP135 and increases its deubiquitinating activity. siRNA experiments revealed that WAC is required for Golgi biogenesis. In an in vitro Golgi reformation assay, WAC was necessary only for p97/p47-mediated Golgi reassembly, but not for p97/p37-mediated reassembly. WAC is hence thought to function in p97/p47-mediated Golgi membrane fusion by activating the deubiquitinating function of VCIP135. We also showed that the two p97 pathways function in ER membrane fusion as well. An in vitro ER reformation assay revealed that both pathways required VCIP135 but not its deubiquitinating activity for their ER membrane fusion. This was consistent with the finding that WAC is unnecessary for p97-mediated ER membrane fusion.     

Barn swallow (<Emphasis Type="Italic">Hirundo rustica</Emphasis>) parents use past information to decide on food provisioning to the brood,but not to decide on allocation within the brood

The begging behavior of birds is thought to influence the allocation of food within the brood (allocation function) or to increase the total amount of food delivered to the brood (delivery function). Considering the nature of the feeding activity of passerines, in which hundreds of feeding events occur in a single day, parents may not necessarily decide the amount of resources allocated to each nestling/brood during a single feeding event. To examine this possibility, the relationship between begging intensity and parental responses to allocation and delivery functions was tested and modeled at multi-temporal scales in the barn swallow (Hirundo rustica). Comparison of models revealed that barn swallow parents differed in the temporal scales at which they respond to nestlings with respect to these two functions. While barn swallow parents decide which nestling to feed at a focal feeding event according to chick begging of the focal feeding event, they integrated past information on total begging effort to determine delivery rates to their offspring during the 14 and 6 min prior to the focal feeding event in males and females, respectively. These findings highlight that it is important to investigate parental response to begging at appropriate temporal scales when analyzing begging functions.     

Transgenic rice plants harboring the grain hardness-locus region of Aegilops tauschii

Grain hardness of wheat is determined by the hardness (Ha)-locus region, which contains three friabilin-related genes: puroindoline-a (Pina), puroindoline-b (Pinb) and GSP-1. In our previous study, we produced the transgenic rice plants harboring the large genomic fragment of the Ha-locus region of Aegilops tauschii containing Pina and GSP-1 genes by Agrobacterium-mediated transformation. To examine the effects of the transgenes in the rice endosperms, we firstly confirmed the homozygosity of the T-DNAs in four independent T₂ lines by using fluorescence in situ hybridization (FISH) and DNA gel blot analyses. The transgenes, Pina and GSP-1, were stably expressed in endosperms of the T₃ and T₄ seeds at RNA and protein levels, indicating that the promoters and other regulatory elements on the wheat Ha-locus region function in rice, and that multigene transformation using a large genomic fragment is a useful strategy. The functional contribution of the transgene-derived friabilins to the rice endosperm structure was considered as an increase of spaces between compound starch granules, resulting in a high proportion of white turbidity seeds.