Expression and activity of trypsin and pepsin during larval development of the spotted rose snapper Lutjanus guttatus

The present study aimed to describe and understand the development of the digestive system in spotted rose snapper (Lutjanus guttatus) larvae from hatching to 40 days post-hatch (dph). The mouth opened between 2 and 3 dph, at that moment the digestive tract was barely differentiated into the anterior and posterior intestine, although the liver and pancreas were already present. Gastric glands were observed until 20 dph, followed by the differentiation of the stomach between 20 and 25 dph. Trypsinogen expression and trypsin activity were detected at hatching, increasing concomitantly to larval development and the change in the type of food. Maximum levels of trypsinogen expression were observed at 25 dph, when animals were fed with Artemia nauplii, and maximum trypsin activity was detected at 35 dph, when larvae were fed with an artificial diet. On the other hand, pepsinogen gene expression was detected at 18 dph, two days before pepsin enzymatic activity and appearance of gastric glands. Maximum pepsin activity was also observed at 35 dph. These results suggest that in this species weaning could be initiated at an earlier age than is currently practiced (between 28 and 30 dph), since larvae of spotted rose snapper develop a functional stomach between days 20 and 25 post-hatch.     

The KNAT2 homeodomain protein interacts with ethylene and cytokinin signaling

Using a transgenic line that overexpresses a fusion of the KNAT2 (KNOTTED-like Arabidopsis) homeodomain protein and the hormone-binding domain of the glucocorticoid receptor (GR), we have investigated the possible relations between KNAT2 and various hormones. Upon activation of the KNAT2-GR fusion, we observed a delayed senescence of the leaves and a higher rate of shoot initiation, two processes that are also induced by cytokinins and inhibited by ethylene. Furthermore, the activation of the KNAT2-GR fusion induced lobing of the leaves. This feature was partially suppressed by treatment with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, or by the constitutive ethylene response ctr1 mutation. Conversely, some phenotypic traits of the ctr1 mutant were suppressed by the activation of the KNAT2-GR fusion. These data suggest that KNAT2 acts synergistically with cytokinins and antagonistically with ethylene. In the shoot apical meristem, the KNAT2 gene is expressed in the L3 layer and the rib zone. 1-Aminocyclopropane-1-carboxylic acid treatment restricted the KNAT2 expression domain in the shoot apical meristem and reduced the number of cells in the L3. The latter effect was suppressed by the activation of the KNAT2-GR construct. Conversely, the KNAT2 gene expression domain was enlarged in the ethylene-resistant etr1-1 mutant or in response to cytokinin treatment. These data suggest that ethylene and cytokinins act antagonistically in the meristem via KNAT2 to regulate the meristem activity.     

The effects of COVID-19 lockdown on jumping performance and aerobic capacity in elite handball players

The aim of this research was to analyse the capacity of a home-based training programme to preserve aerobic capacity and jumping performance in top-level handball players during the COVID-19 lockdown. Eleven top-level male handball players from the same team participated in the study. A submaximal shuttle run test and a counter-movement jump test were used to measure the players’ aerobic fitness and lower limb explosive strength, respectively. A 9-week home-based training programme was followed during lockdown. Pre-test measurements were assessed before the pandemic on 29 January 2020 and ended on 18 May 2020. Moderate significant mean heart rate increases were found in the late stages of the submaximal shuttle run test after the lockdown (stage 5, 8.6%, P = 0.015; ES = 0.873; stage 6, 7.7%, P = 0.020; ES = 0.886; stage 7, 6.4%, P = 0.019; ES = 0.827). Moderate significant blood lactate increases were observed immediately after the submaximal shuttle run test following the lockdown (30.1%, P = 0.016; ES = 0.670). In contrast, no changes were found in jump performance. A structured home-based training programme during the COVID-19 lockdown preserved lower limb explosive strength but was an insufficient stimulus to maintain aerobic capacity in top-level handball players.     

Effects of small-scale turbulence on feeding rate and gross-growth efficiency of three Acartia species (Copepoda: Calanoida)

Experiments designed to test the effects of small-scale turbulenceon the feeding rates and gross-growth efficiency of calanoidcopepods have been performed within a wide range of controlledfood concentrations. Turbulence significantly enhanced feedingrates only at food concentrations lower than the ingestion saturatinglevel. Gross-growth efficiency (the quotient carbon-egg production/carbon-foodingested) of the different Acartia species studied showed differentpatterns of response to turbulence, in agreement with the hydrodynamiccharacteristics of their habitat. Furthermore, experiments conductedon Acartia clausi at two different intensities of turbulenceindicate a shift in the response, with enhancement of feedingat low intensities of turbulence and negative interference athigher intensities.     

Thr-90 plays a vital role in the structure and function of bacteriorhodopsin

The role of Thr-90 in the bacteriorhodopsin structure and function was investigated by its replacement with Ala and Val. The mutant D115A was also studied because Asp-115 in helix D forms a hydrogen bond with Thr-90 in helix C. Differential scanning calorimetry showed a decreased thermal stability of all three mutants, with T90A being the least stable. Light-dark adaptation of T90A was found to be abnormal and salt-dependent. Proton transport monitored using pyranine signals was approximately 10% of wild type for T90A, 20% for T90V, and 50% for D115A. At neutral or alkaline pH, the M rise of these mutants was faster than that of wild type, whereas M decay was slower in T90A. Overall, Fourier transform infrared (FTIR) difference spectra of T90A were strongly pH-dependent. Spectra recorded on films adjusted at the same pH at 243 or 277 K, dry or wet, showed similar features. The D115A and T90V FTIR spectra were closer to WT, showing minor structural differences. The band at 1734 cm(-1) of the deconvoluted FTIR spectrum, corresponding to the carboxylate of Asp-115, was absent in all mutants. In conclusion, Thr-90 plays a critical role in maintaining the operative location and structure of helix C through three complementary interactions, namely an interhelical hydrogen bond with Asp-115, an intrahelical hydrogen bond with the peptide carbonyl oxygen of Trp-86, and a steric contact with the retinal. The interactions established by Thr-90 emerge as a general feature of archaeal rhodopsin proteins.     

Clinical variables predicting the risk of a hospital stay for longer than 7 days in patients with severe acute exacerbations of chronic obstructive pulmonary disease: a prospective study

Background

Chronic obstructive pulmonary disease (COPD) patients may experience an acute exacerbation (AECOPD) that requires hospitalisation. The length of hospital stay (LHS) has a great economic impact on the health-care system. Knowing the predictors of prolonged LHS could help to identify possible interventions.

Methods

We performed a prospective study to identify the clinical predictors of prolonged LHS in patients hospitalised for AECOPD. We divided the study sample by LHS into normal (≤7?days) and prolonged LHS (>?7?days) groups. Outcomes were the need for non-invasive and invasive mechanical ventilation (NIMV and IMV), intensive care unit (ICU) admission, and the 3-year mortality.

Results

We enrolled 437 patients, of which 213 and 224 had normal LHS and prolonged LHS, respectively. Patients with a prolonged LHS had more prior hospitalisations for AECOPD, a worse mMRC (modified Medical Research Council) dyspnoea score, a higher prevalence of long-term oxygen therapy and a higher rate of congestive heart disease. During the current admission, this group also tended to require NIMV, IMV and ICU admission and the mortality risks at 6?months, 1?year and 3?years were higher. In the multivariate regression analysis, an mMRC dyspnoea score?≥?2 (odds ratio-OR 2.24; 95% confidence interval-CI 1.34 to 3.74; p?=?0.002) and the presence of acute respiratory acidosis (OR 2.75; 95% CI 1.49 to 5.05; p?=?0.001) predicted a prolonged LHS at admission.

Conclusions

The presence of an mMRC ≥2 and acute respiratory acidosis at admission independently increased the risk of a prolonged LHS for AECOPD.

     

Sperm ultrastructure of the spider crab Maja brachydactyla (Decapoda: Brachyura)

This study describes the morphology of the sperm cell of Maja brachydactyla, with emphasis on localizing actin and tubulin. The spermatozoon of M. brachydactyla is similar in appearance and organization to other brachyuran spermatozoa. The spermatozoon is a globular cell composed of a central acrosome, which is surrounded by a thin layer of cytoplasm and a cup‐shaped nucleus with four radiating lateral arms. The acrosome is a subspheroidal vesicle composed of three concentric zones surrounded by a capsule. The acrosome is apically covered by an operculum. The perforatorium penetrates the center of the acrosome and has granular material partially composed of actin. The cytoplasm contains one centriole in the subacrosomal region. A cytoplasmic ring encircles the acrosome in the subapical region of the cell and contains the structures‐organelles complex (SO‐complex), which is composed of a membrane system, mitochondria with few cristae, and microtubules. In the nucleus, slightly condensed chromatin extends along the lateral arms, in which no microtubules have been observed. Chromatin fibers aggregate in certain areas and are often associated with the SO‐complex. During the acrosomal reaction, the acrosome could provide support for the penetration of the sperm nucleus, the SO‐complex could serve as an anchor point for chromatin, and the lateral arms could play an important role triggering the acrosomal reaction, while slightly decondensed chromatin may be necessary for the deformation of the nucleus. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

PARASITIC SPECIES OF THE GENUS BLASTODINIUM (BLASTODINIPHYCEAE) ARE PERIDINIOID DINOFLAGELLATES1

The taxonomic position of Blastodinium navicula Chatton and B. contortum Chatton, parasites of marine copepods, was investigated on the basis of morphological observations and molecular data. The life cycle of Blastodinium includes a parasitic stage, a trophont, and free‐swimming dinospores. The individual cells in the trophont, as well as the dinospores that they produced, were thecate. Dinospores of B. contortum and B. navicula had peridinioid plate tabulation formula, demonstrating an affiliation to the order Peridiniales Heackel (subdivision Dinokaryota Fensome et al.). This systematic position is in contrast to current classifications, in which the order Blastodiniales Chatton is thought to represent an early evolutionary branch of the dinokaryote lineage. Small‐subunit rRNA gene sequences were generated from six Blastodinium individuals isolated from three different host species. In phylogenetic analyses based on SSU rRNA genes, Blastodinium spp. branched with the typical dinoflagellates. Even though overall statistical support was low, the analyses suggested that Blastodinium spp. are late‐branching, dinokaryote dinoflagellates. Species currently included in Blastodiniales are all parasites, but they are morphologically and functionally diverse. Emerging molecular data also reveal high genetic diversity, and therefore, the taxonomy of the group requires reevaluation.     

Use of ion trap gas chromatography–tandem mass spectrometry for detection and confirmation of anabolic substances at trace levels in doping analysis

A procedure for detecting and confirming 23 anabolic substances and/or metabolites has been developed using a GC–MS–MS ion trap system in full-scan mode. The process used to select the precursor ion, and the optimization of the system parameters used to obtain the daughter ion spectra, are explained. Urine samples were prepared using solid-phase extraction and enzymatic hydrolysis, and after TMS derivatives had been formed, they were injected into the mass spectrometer. This method permits confirmation of the presence of anabolic substances at low ng ml⁻¹ levels without the need of further purification procedures on the samples. This procedure has been used on more than 2000 urine samples collected from sporting competitions and has made it possible to confirm more than 45 true positive cases which could not have been confirmed using routine GC–MS methods.