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Pen shell (Atrina pectinata) is a Bivalvia species with high commercial value in China. However, large scale production is difficult owing to the lack of seed. Pen shell uses external fertilization with sperm stored in the testis in a nonmotile state. Sperm motility is initiated when they are released from the reproductive tract into the aquatic environment, which enables fertilization. Various chemical signals including pH, ions, and cyclic nucleotides control sperm motility. However, there are interspecific differences in activation conditions between different Bivalvia species. Screening out an effective activating medium is the basis of artificial breeding technology.Swimming parameters, such as total motile sperm (TM), movement velocity, and beat-cross frequency (BCF) are common indicators to evaluate sperm quality. Sperm must have sufficient motility to reach the egg to complete fertilization. In addition, sperm needs a large amount of ATP to maintain its swimming movement. Intracellular ATP content controls the duration of the sperm movement phase in most marine species. Studying the movement characteristics and energy metabolism of sperm during activation will help develop and optimize artificial breeding technology. Studies of A. pectinata mainly focus on their oocytes. However, the activation conditions, moving characteristics, and energy metabolism of sperm during activation remains unknown. Thus, there is an urgent need to screen appropriate media and study the activation mechanisms of A. pectinata sperm.Adult A. pectinata were collected from Wuzhizhou Island, Hainan Province in November 2021. Artificial seawater with different levels of ammonia ions and pH were used to activate sperm. This study examined A. pectinata sperm activation in artificial seawater by varying the ammonia ion concentration and pH. The change in sperm motility, curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), and BCF were described. The ATP content, ATPase activities, and superoxide dismutase (SOD) activity were quantitatively recorded during the full activated stage. The motility was slightly improved by increasing the pH of seawater, but could not achieve the fully activated stage. Furthermore, the motility was significantly improved when activated by alkalized seawater containing ammonia ions, and the best results were observed in groups containing 3 mmol/L ammonia ion: The sperm motility index (MI) was in the fully activated stage (MI ≥ 4) until the end of the experiment, with TM ≥ 80%, VCL > 56 μm/s, VSL > 17 μm/s, VAP > 30 μm/s, and BCF > 6 Hz. Sperm ATP content decreased to 30.29% of their initial values [(128.80±66.92) μmol/g prot] during 5 min post activation and was maintained at this level during post-activation. ATPase activities were maintained at a constant level. Na+-K+-ATPase activity was lower [(0.62±0.03) U/mg prot] compared to Ca2+-Mg2+-ATPase activity [(6.08±0.04) U/mg prot]. The SOD activity of sperm steadily decreased to [(1.23±0.73) U/mg prot] during 15 min post activation and remained stable.In conclusion, pH was not the decisive factor in pen shell sperm motility. Instead, ammonium ion promoted sperm activation. There was a significant decrease in sperm ATP concentration (P

The diurnal and nocturnal valve gaping behavior of the pearl oyster Pteria penguin was characterized through video analysis aided by open-source software. Juvenile pearl oysters were video-recorded for 48 hours under laboratory conditions, using commonly used surveillance hardware. The direct measuring of the distance changes between the two valve edges effectively revealed the pearl oysters’ tendency to open their valves wider at night-time, than during day-time. Moreover, the differences observed were also attained at the individual level. The description for the first time of this behavior has broader implications for the research in pearl oyster aquaculture. Moreover, it introduces a non-invasive tool for comprehensive assessment of adult oyster behavior.

The effect of different background colors (red, yellow, blue, green, white, and black) on crayfish Cherax quadricarinatus juveniles was evaluated over a 50-day rearing period. Survival, growth, body color, and enzymatic activity were assessed. At the experiment's conclusion, survival, growth, and weight were calculated. Body color was analyzed using Lab color composition, and enzyme activities (amylase, lipase, superoxide dismutase, catalase) were assessed in the dissected hepatopancreas. Results showed no effect of background color on survival rate (P > 0.05). However, crayfish reared against black and red backgrounds exhibited significantly higher weight, growth rate, and condition factor compared to those on white and yellow backgrounds (P

The electron trapping or attachment cross section of carbon dioxide (CO2) condensed as thin films on a spacer of Ar is obtained using a simple model for electron trapping in a molecular film and then charge releasing from the same film by photon absorption. The measurements are presented for different electron exposures and impact energies, film thicknesses, and probing photon energies. The cross section for trapping an electron of incident energy between 0 and 5 eV reveals three different attachment processes characterized by a maximum at about 0.75 eV, a structured feature around 2.25 eV, and a shoulder around 3.75 eV. From the measurement of their dependence with the probing photon energy, the two lowest processes produce traps having a vertical electron binding energy of ∼3.5 eV, whereas the highest one yields a slightly higher value of ∼3.7 eV. The 0.75 eV maximum corresponds to the formation of vibrational Feshbach resonances in (CO2)n- anion clusters. The 2.25 eV feature is attributed to the formation of a vibrationally excited 2Πu anion in (CO2)n- clusters, followed by fast decay into its vibrational ground state without undergoing autodetachment. Finally, 3.75 eV shoulder is assigned to the well-known dissociative electron attachment process from 2Πu anion state producing the O- anion in the gas phase and the (CO2)nO- anions in clusters. [ABSTRACT FROM AUTHOR]

The electron trapping or attachment cross section of carbon dioxide (CO2) condensed as thin films on a spacer of Ar is obtained using a simple model for electron trapping in a molecular film and then charge releasing from the same film by photon absorption. The measurements are presented for different electron exposures and impact energies, film thicknesses, and probing photon energies. The cross section for trapping an electron of incident energy between 0 and 5 eV reveals three different attachment processes characterized by a maximum at about 0.75 eV, a structured feature around 2.25 eV, and a shoulder around 3.75 eV. From the measurement of their dependence with the probing photon energy, the two lowest processes produce traps having a vertical electron binding energy of ∼3.5 eV, whereas the highest one yields a slightly higher value of ∼3.7 eV. The 0.75 eV maximum corresponds to the formation of vibrational Feshbach resonances in (CO2)n- anion clusters. The 2.25 eV feature is attributed to the formation of a vibrationally excited 2Πu anion in (CO2)n- clusters, followed by fast decay into its vibrational ground state without undergoing autodetachment. Finally, 3.75 eV shoulder is assigned to the well-known dissociative electron attachment process from 2Πu anion state producing the O- anion in the gas phase and the (CO2)nO- anions in clusters. [ABSTRACT FROM AUTHOR]

We propose an apparatus and method, based on the absorption of photon of energy ranging between 1.5 and 3.54 eV, to measure the absolute cross section for trapping low-energy electrons in a molecular film deposited on a metal substrate. A simple model is described to analyze electron trapping in the film and charge release from the same film by photon excitation. Measurements of the trapping of electrons in multilayer films of n-hexane are presented for different film thicknesses, electron exposures and incident energies, and probing photon fluxes and energies. The electron trapping cross section in a five-layer film of n-hexane is characterized by a large maximum reaching a value of (4.7±0.4)×10-17 cm2 at 10 eV and having a 2.3 eV full width at half maximum. This feature is ascribed to the formation of one or several core-excited resonances lying between 7 and 14 eV and leading, via dissociative electron attachment, to the formation of stable H- fragments, which stabilize within the first outerlayer of the film. [ABSTRACT FROM AUTHOR]

Abstract Magnetic refrigeration offers an energy efficient and environmental friendly alternative to conventional vapor‐cooling. However, its adoption depends on materials with tailored magnetic and structural properties. Here a high‐throughput computational workflow for the design of magnetocaloric materials is introduced. Density functional theory calculations are used to screen potential candidates in the family of MM'X (M/M’ = metal, X = main group element) compounds. Out of 274 stable compositions, 46 magnetic compounds are found to stabilize in both an austenite and martensite phase. Following the concept of Curie temperature window, nine compounds are identified as potential candidates with structural transitions, by evaluating and comparing the structural phase transition and magnetic ordering temperatures. Additionally, the use of doping to tailor magnetostructural coupling for both known and newly predicted MM'X compounds is predicted and isostructural substitution as a general approach to engineer magnetocaloric materials is suggested.

O artigo apresenta compreensões sobre as condições de acesso a internet e as Tecnologias Digitais de Informação e Comunicação (TDIC) na visão dos professores da área de Ciências da Natureza do Estado do Rio Grande do Sul. A partir de um estudo de diagnóstico, de abordagem qualitativa e quantitativa, coletou-se ao longo do primeiro semestre de 2022 as percepções de 35 professores da rede pública do RS em relação a possíveis modificações das condições de acesso TDIC e a internet no contexto escolar/rede de ensino durante a pandemia. Os resultados indicam uma ampliação da disponibilização de acesso a web e as plataformas digitais na escola a partir do momento Pandêmico. Aponta-se também que ainda existem limitações no contexto educativo, como: a falta de qualidade da rede wifi; o não acesso dos estudantes na plataforma; a não disponibilização de programas e softwares aos professores; falta de formação na escola dos estudantes e professores com enfoque no uso adequado das TDIC em atividades de ensino e da aprendizagem.

The effects of fresh and spray-dried microalgal diets on the growth, digestive enzymatic activity, and gut microbial community were investigated in juveniles of the winged pearl oyster Pteria penguin. A total of 240 pearl oysters were fed either live or spray-dried unialgal diets of the species Isochrysis zhanjiangensis and Platymonas subcordiformis at a final concentration of 150,000 cells/mL. The experiment was performed over 28 days in triplicate feeding trials under laboratory conditions. At the end of the feeding trials, the hepatopancreas and gut tissue were dissected to quantify the digestive enzymatic activity and analyze the gut bacterial community. The survival rate of the oyster juveniles in all trials was > 90 %. Moreover, the animals fed a spray-dried P. subcordiformis diet exhibited slightly higher shell growth rates. However, the mean shell height and the total wet weight were not significantly different among all experimental groups (P > 0.05). The digestive enzymes amylase, pepsin, and lipase exhibited significantly higher activity levels in oysters fed spray-dried diets than in those provided live microalgae. The different diets also provoked changes in the gut microbiota of the pearl oysters. A total of 27 phyla and 482 genera were detected within all groups examined; the Proteobacteria, Cyanobacteria, Bacteroidetes, and Spirochaetes were the dominant phyla. In general, spray-dried diets exhibited a higher number of operational taxonomic units (OTUs), Chao1, and Simpson and Shannon indices, implying the ability of these diets to promote high microbial biodiversity. Thus, these diets benefitted the maintenance of the intestinal micro-ecological balance and health. The study findings will help optimize intermediate culture technology and management of P. penguin juveniles.

The human pathogen Neisseria meningitidis colonizes blood vessels and causes vascular damage, despite a neutrophil-rich inflammatory infiltrate. Here, Manriquez et al. use a humanized mouse model to show that pathogen colonization of capillaries and arterioles creates an intravascular niche that precludes an effective action of neutrophils.

This study describes the shell color polymorphism and its correspondent metabolic activities in hatchery-reared Pinctada maxima juveniles. Analysis of color distances assessed the similarities among the different phenotypes (Ph); from the most common Ph-1 (gray), Ph-2 (bronze), Ph-3 (white), Ph-4 (brown), Ph-5 (green), Ph-6 (purple), and Ph-7 (yellow). Yellow-colored shells (Ph-7) were found less unrelated to the other colored shells and also exhibited higher enzymatic activity; particularly in enzymes that have been linked to yellow or golden shell color in different bivalves. By contrast, green-colored shells (Ph-5) exhibited comparatively higher levels of enzymes (e.g. tyrosinase, superoxide dismutase) known to promote fast growth in various organisms, which is consistent considering that green-colored shells also exhibited the largest biometric values. These findings open the possibility to use shell color as a reliable indicator to breed high-quality P. maxima pearl oysters.

Abstract The effect of low salinity levels on byssal re‐attachment behavior in Pteria penguin juveniles was observed in the laboratory. Juvenile pearl oysters were submerged in seawater blended to 8.0, 12.0, 16.0, 20.0, 24.0, 28.0, and 32.0 salinity levels for a period of 48 hr. The sub‐lethal salinity level was greater than 20.0 psu. Although salinity levels of 20.0 and 24.0 psu did not affect the oyster survival, the observed byssogenesis activity was significantly reduced and locomotion activity was delayed. Description of the effects of low salinity levels on the byssal re‐attachment behavior of P. penguin juveniles provides a foundation for the design of more complex experiments and approaches to further the exploration and development of improved pearl production techniques.

Industrial farming is an alternative mode for Pinctada maxima juvenile cultivation to avoid mass mortality caused by natural disasters. Suitable and enough food is crucial for successful industrial bivalve farming. To investigate the feasibility of live microalga instead of spray-dried microalgal powder in P. maxima juvenile industrial farming, this study replaces a positive control live microalgal diet [Isochrysis zhanjiangensis (L-iso) and Platymonas subcordiformis (L-pla)] with spray-dried I. zhanjiangensis powder (P-iso) and P. subcordiformis powder (P-pla). Continuous feeding trials (30 days) were conducted on the P. maxima juvenile (1.2008 ± 0.0009 g initial weight and 30.12 ± 0.05 mm initial shell length), under laboratory conditions. Survival, growth performance, and intestinal microbial community were studied and compared across the groups. Results showed that survival rate (SR) did not differ significantly across the groups (ranged from 84 to 86%, P > 0.05). The growth performance in spray-dried microalgal groups, including total weight (TW), shell height (SH), absolute growth rate (AGR), and relative growth rate (RGR) for SH and TW, was slightly lower than that in live microalgal groups, while the activities of pepsin (PES), amylase (AMS), and lipase (LPS) were significantly higher (P < 0.05). The best growth performance was observed in the L-iso group, followed by the L-pla group. A 16S rRNA-based sequencing revealed that Proteobacteria was the dominant phylum in P. maxima juvenile intestinal bacterial community under controlled conditions, which accounted for 62–82% across groups. The intestinal bacteria at the genus level were more sensitive to diets, whereas Burkholderia was the dominant genus in both L-iso (66.52 ± 6.43%) and L-pla groups (54.00 ± 5.66%), while Mycoplasma, Alphaproteobacteria, and Oxyphotobacteria were in both P-iso and P-pla groups. The P-pla group got higher ACE, Chao1, and Simpson and Shannon indices (P < 0.05). The above results suggested that the spray-dried P-iso and P-pla can serve as substitutes for live microalga in P. maxima juvenile industrial farming under controlled conditions. The finding in this study provides basic data to optimize industrial farming technology and healthy management for P. maxima juvenile.

Light is one of the most important environmental factors affecting the growth and reproduction of algae. In this study, the effect of various LED colors on the productivity, chlorophyll (Chl-a, Chl-b, and total Chl), protein, and carbohydrate content of Isochrysis zhanjiangensis in indoor culture was investigated. Microalgae monocultures were cultivated under five different colors (red, green, blue, yellow, and white) for twenty-one days. The microalgae cultured under red light exhibited a higher specific growth rate (0.4431 ± 0.0055 µ day−1), and under white light a higher productivity (0.0728 ± 0.0013 g L−1 day−1). The poorest performance was observed under yellow and green lights. Interestingly, green light exhibited the highest levels of chlorophylls (Chl-a, 1.473 ± 0.037 mg L−1; Chl-b, 1.504 ± 0.001 mg L−1; total Chl, 2.827 ± 0.083 mg L−1). The highest protein content was observed under the white light (524.1935 ± 6.5846 mg L−1), whereas the carbohydrate content was remarkably high under the blue light (24.4697 ± 0.0206 mg L−1). This study is important in terms of the selection of light at the appropriate color (wavelength) to increase the content of organic compounds desired to be obtained indoors with the potential for commercially produced cultures.