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Zooplanktons play an important role in the whole freshwater ecosystem, which are the main quality food for almost all fish in their juvenile stage and are the main basic component of the high trophic levels in the aquatic food web. In the context of global environmental change, freshwater zooplankton is experiencing rapid loss of biodiversity and ecosystem integrity. However, our understanding of the geographical distribution pattern of freshwater zooplankton and the diversity-affected ecological factors is still very limited. In order to investigate the research status and future development trend of zooplankton in global freshwater, 26176 publications about freshwater zooplankton/zooplankter indexed by Web of Science from 1991 to 2020 were analyzed with a bibliometric approach in our study. The research contents mainly included the output trend of publications related to the freshwater zooplankton/zooplankter filed over time, the journals with greatest number of zooplankton publications, the countries from which the authors came from, the co-authors and cooperation across countries, the associated keywords in the research areas and so on. This study was searched on a scientific website for scientific study that have limited scientific relevance for the future researches on the freshwater zooplankton. [ABSTRACT FROM AUTHOR]

To explore the spatial and temporal distribution characteristics of phytoplankton functional groups (PFGs) of the Dongta spawning grounds in the Pearl River, China, quarterly surveys of this area were carried out during March, 2016 to December, 2018, and the ecological status was analyzed and evaluated according to PFGs assemblage index (Q index). 26 PFGs were identified, and the dominant PFGs were C, D, J, K, L0, MP, N, P, S1, S2, T, W1, W2, X2, Y in this area. Phytoplankton Q indexes varied from 1.83 to 3.73, with the mean value 2.91, which showed that the ecological status of the Dongta spawning grounds was “medium” and “good”, but parts occasionally were “tolerable”. Temporally, the general ecological status was good in March and June, but it was medium in September and December. Basing on our study, the results showed that: (1) factors including water velocity (V), DO, Chla, phosphate, oxidation reduction potential, total phosphorus, electrical conductivity, total dissolved solid and salinity were significantly correlated with the dominant PFGs; (2) the phytoplankton Q index was significantly correlated with the V. It was suggested that after the construction and operation of Datengxia Water Dam and its upper reaches cascade dams, attention should be paid to regulate the water flow and velocity in the lower reaches of the river by means of ecological operation, so as to ensure the functions of the spawning grounds and protect the fishery conservation zones in the mainstream of the Pearl River. [ABSTRACT FROM AUTHOR]

There is often intense competition among species in an environment with limited resources and space, leading to the exclusion of inferior competitors, reduced species diversity, and changes in zooplankton communities. This study investigated the interspecific competition between two dominant rotifer species in the Pearl River Basin, Brachionus calyciflorus and Keratella valga, through laboratory experiments at different temperatures, food concentrations, and initial rotifer densities. In separate cultures, the population growth of both rotifer species was affected by changes in temperature, food density, and initial density. In mixed cultures, B. calyciflorus was inhibited by competition, leading to an overall decrease in its population growth rate and maximum population density. K. valga was also affected by competition, leading to an increase in its population growth rate and maximum population density at 20 ℃ or at an initial density of 1.0 × 106 cells/mL. B. calyciflorus was excluded by K. valga at low and medium food concentrations (0.5 × 106 and 1.0 × 106 cells/mL), whereas the opposite was found at high food concentration (3.0 × 106 cells/mL). Food concentration is obviously the main factor affecting outcome. Temperature, initial density, and interactions between the three factors also have an effect on it. [ABSTRACT FROM AUTHOR]

The ability to bind iodine-labelled human growth hormone ([125I]hGH) was measured in different parts of the human brain. The choroid plexus contained the highest amount of binding sites (receptors) and was therefore selected for further studies. The binding between [125I]hGH and the receptor was saturable, of high affinity (Ka = 0.63 nM-1) and pH- as well as time-dependent. After solubilization with Triton X-100 the receptors retained their hormone-binding properties and eluted in the high molecular weight range (greater than 500,000) upon molecular sieve chromatography. Analysis by an affinity cross-linking technique indicated a hormone-binding unit of molecular weight 51,000. The molecular characteristics of the identified binding sites are discussed in comparison to those of growth hormone receptors of human and animal origin.