Search

The cost of reproduction is the core driver of life history evolution in animals. This paper demonstrates that the cumulative distance moved and the duration of movement of sexually immature abalones, Haliotis discus hannai, kept in various male and female groups, were significantly higher than those of sexually mature individuals, except when kept in mixed cultures of mature males and females. After mixed‐culture, sexually mature males moved significantly further and for a longer duration than mature female abalones, and even more so than mature male abalones of any other group. Examination of the LC‐MS metabolomics of mature males cultured with sexually mature females (AM) and those cultured with sexually immature females (JM) showed that cyclic adenosine monophosphate (cAMP) acted as a differential metabolic biomarker. After 24‐h uninterrupted sampling, the concentration of 5‐HT and the expression levels of the 5‐HT2 and 5‐HT6 receptors in AM were significantly higher than those in JM. After further injection of 5‐HT2 and 5‐HT6 receptor antagonists, the concentrations of cAMP and PKA rose again, but the cumulative movement duration and distance of male abalones decreased significantly, showing that 5‐HT was involved in the regulation of movement behavior of male abalones through the 5‐HT2 and 5‐HT6 receptor‐activated cAMP‐PKA pathways. The results demonstrated a significant increase in the movement endurance of mature male abalones cultured with mature females, providing a theoretical basis for understanding the adaptive life history strategies of abalones and suggesting ways to protect diverse benthic resources for abalones during the reproductive stage. [ABSTRACT FROM AUTHOR]

Metallic phase (1T) MoS2 has been regarded as an ideal catalytic material for the hydrogen evolution reaction (HER) due to its high active site density and favorable electrical conductivity. However, the preparation of 1T-phase MoS2 samples requires tough reaction conditions and 1T-MoS2 has poor stability under alkaline conditions. In this work, 1T-MoS2/NiS heterostructure catalysts grown in situ on carbon cloth were prepared by a simple one-step hydrothermal method. The obtained MoS2/NiS/CC combines the advantages of high active site density and a self-supporting structure, achieving stable 77% metal phase (1T) MoS2. The combination of NiS and 1T-MoS2 enhances the intrinsic activity of MoS2 while the electrical conductivity is improved. These advantages enable the 1T-MoS2/NiS/CC electrocatalyst to have a low overpotential of 89 mV (@10 mA cm−2) and a small Tafel slope of 75 mV dec−1 under alkaline conditions and provide a synthetic strategy of stable 1T-MoS2-based electrocatalysts for the HER by a heterogeneous structure. [ABSTRACT FROM AUTHOR]

Settlement and metamorphosis is the key stage during which Haliotis discus hannai larvae change from planktonic to benthic life. Larvae tend to be highly sensitive to changes in the external environment, which can result in increased mortality. In the aquaculture industry, increasing the metamorphosis rate of larvae is considered to be a critical factor for increasing yield. In this study, we modified a recirculating aquaculture system (RAS) for dense rearing of abalone larvae. We set up five density groups (1, 5, 10, 20 and 40 ind/ml) and compared the effects of traditional aquaculture (TA) and the RAS on the hatching success rate, metamorphosis rate and the expression levels of metamorphosis‐related genes. At stocking densities of 1, 5 and 10 ind/ml, the survival rate, metamorphosis rate and expression levels of MIRP, α2ADR and DopR2 in both culture modes were significantly higher than those in the 20 and 40 ind/ml densities (p < 0.05). The metamorphosis rate and survival rate of larvae in the RAS groups were significantly higher than those in the TA groups (p < 0.05). Under TA at the 40 ind/ml stocking density, the dissolved oxygen concentration in the water declined and the TAN concentration significantly increased (p < 0.05). As the stocking density increased, the size of metamorphosed larvae under each mode tended to increase in both culture modes. In particular, when the density was highest, the time required for metamorphosis was significantly extended (p < 0.05). Based these results, use of the RAS with stocking density of 10 ind/ml would maintain a stable aquaculture water environment, prevent fertilized eggs from hatching or becoming densely aggregated before larval metamorphosis, and significantly increase the stocking density per unit water. These results provide an important reference for scaling up reproduction of larval abalone and further developing the culture mode for this economically important shellfish. [ABSTRACT FROM AUTHOR]

Metallic phase (1T) MoS 2 has been regarded as an ideal catalytic material for the hydrogen evolution reaction (HER) due to its high active site density and favorable electrical conductivity. However, the preparation of 1T-phase MoS 2 samples requires tough reaction conditions and 1T-MoS 2 has poor stability under alkaline conditions. In this work, 1T-MoS 2 /NiS heterostructure catalysts grown in situ on carbon cloth were prepared by a simple one-step hydrothermal method. The obtained MoS 2 /NiS/CC combines the advantages of high active site density and a self-supporting structure, achieving stable 77% metal phase (1T) MoS 2 . The combination of NiS and 1T-MoS 2 enhances the intrinsic activity of MoS 2 while the electrical conductivity is improved. These advantages enable the 1T-MoS 2 /NiS/CC electrocatalyst to have a low overpotential of 89 mV (@10 mA cm -2 ) and a small Tafel slope of 75 mV dec -1 under alkaline conditions and provide a synthetic strategy of stable 1T-MoS 2 -based electrocatalysts for the HER by a heterogeneous structure.

Primitive cnidarians are crucial for elucidating the early evolution of metazoan body plans and life histories in the late Neoproterozoic and Palaeozoic. The highest complexity of both evolutionary aspects within cnidarians is found in extant hydrozoans. Many colonial hydrozoans coated with chitinous exoskeletons have the potential to form fossils; however, only a few fossils possibly representing hydroids have been reported, which still require scrutiny. Here, we present an exceptionally well-preserved hydroid found in the Upper Cambrian Fengshan Formation in northern China. It was originally interpreted as a problematic graptolite with an uncertain systematic position. Based on three characteristic morphological traits shared with extant hydroids (with paired hydrothecae, regular hydrocaulus internodes and special intrathecal origin pattern of hydrocladium), we propose this fossil hydroid as a new genus, Palaeodiphasia gen. nov., affiliated with the advanced monophyletic hydrozoan clade Macrocolonia typically showing loss of the medusa stage. More Macrocolonia fossils reviewed here indicate that this life strategy of medusa loss has been achieved already as early as the Middle Devonian. The early stratigraphical appearance of such advanced hydroid contrasts with previous molecular hypotheses regarding the timing of medusozoan evolution, and may be indicative for understanding the Ediacaran cnidarian radiation.