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BackgroundChoroid plexus epithelial cells express high levels of transthyretin, produce cerebrospinal fluid and many of its proteins, and make up the blood-cerebrospinal fluid barrier. Choroid plexus epithelial cells are vital to brain health and may be involved in neurological diseases. Transgenic mice containing fluorescent and luminescent reporters of these cells would facilitate their study in health and disease, but prior transgenic reporters lost expression over the early postnatal period.MethodsHuman bacterial artificial chromosomes in which the transthyretin coding sequence was replaced with DNA for tdTomato or luciferase 2 were used in pronuclear injections to produce transgenic mice. These mice were characterized by visualizing red fluorescence, immunostaining, real-time reverse transcription polymerase chain reaction, and luciferase enzyme assay.ResultsReporters were faithfully expressed in cells that express transthyretin constitutively, including choroid plexus epithelial cells, retinal pigment epithelium, pancreatic islets, and liver. Expression of tdTomato in choroid plexus began at the appropriate embryonic age, being detectable by E11.5. Relative levels of tdTomato transcript in the liver and choroid plexus paralleled relative levels of transcripts for transthyretin. Expression remained robust over the first postnatal year, although choroid plexus transcripts of tdTomato declined slightly with age whereas transthyretin remained constant. TdTomato expression patterns were consistent across three founder lines, displayed no sex differences, and were stable across several generations. Two of the tdTomato lines were bred to homozygosity, and homozygous mice are healthy and fertile. The usefulness of tdTomato reporters in visualizing and analyzing live Transwell cultures was demonstrated. Luciferase activity was very high in homogenates of choroid plexus and continued to be expressed through adulthood. Luciferase also was detectable in eye and pancreas.ConclusionsTransgenic mice bearing fluorescent and luminescent reporters of transthyretin should prove useful for tracking transplanted choroid plexus epithelial cells, for purifying the cells, and for reporting their derivation from stem cells. They also should prove useful for studying transthyretin synthesis by other cell types, as transthyretin has been implicated in many functions and conditions, including clearance of β-amyloid peptides associated with Alzheimer’s disease, heat shock in neurons, processing of neuropeptides, nerve regeneration, astrocyte metabolism, and transthyretin amyloidosis.

Algae biomass and community structure can reflect the current situation of a lake, especially in response to changes in light intensity. The relationship between chlorophyll a (Chl a) and chlorophyll b (Chl b) ratio and the proportion of Chlorophyta within the algae community were analyzed in this study. Results showed that light was more intense in August than in March. Algae density in August was greater than in March. The concentration of Chl a and b was influenced by light intensity level. In March, Microcystis and Kirchneriella sp dominated surface water, where the light intensity was over 216 lmol m -2 s -1 , Gloeocapsa, Dictyospaerium pulchellum, and Scenedesmus dominated intermediate water, where the light ranged from 36 to 216 lmol m -2 s -1 . Asterionella formosa Hassall and Mougeotia scalaris dominated near the bottom, where the light was below 36 lmol m -2 s -1 . In August, Microcystis and Selenastrum reinsch dominated surface water, where the light was above 18 lmol m -2 -s -1 . Chroococcus, Chlorella, and Scendesmus quadricauda dominated intermediate water, where light ranged from 90 to 180 lmol m -2 s -1 . Anabaena spirioides and Pediastrum simplex dominated bottom water, where the light was below 90 lmol m -2 s -1 . According to the mean value of Chlorophyta density and algae cell density in three different water levels, the ratio of Chlorophyta and algae community declined from March to August, ranging from 12. 35-21.41 to 4.28-11.19 %. The mean value ratio of Chl b and Chl a in three different water levels showed the same tendency from March to August, ranging from 18.05-21.77 to 15.15-17.44 %. These variations in chlorophyll ratio and Chlorophyta ratio indicated that the structure of the algae community structure was influenced by differences in light intensity.

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ZM-V was designed by the interior imidazole and benzopyrene moieties serving as rotators, which could spin around multiple C-C bonds in the conjugated skeleton. The fluorescence intensity of ZM-V changed...