Factors affecting the quality of therapeutic proteins in recombinant Chinese hamster ovary cell culture

Chinese hamster ovary (CHO) cells are the most widely used mammalian host cells for the commercial production of therapeutic proteins. Fed-batch culture is widely used to produce therapeutic proteins, including monoclonal antibodies, because of its operational simplicity and high product titer. Despite technical advances in the development of culture media and cell cultures, it is still challenging to maintain high productivity in fed-batch cultures while also ensuring good product quality. In this review, factors that affect the quality attributes of therapeutic proteins in recombinant CHO (rCHO) cell culture, such as glycosylation, charge variation, aggregation, and degradation, are summarized and categorized into three groups: culture environments, chemical additives, and host cell proteins accumulated in culture supernatants. Understanding the factors that influence the therapeutic protein quality in rCHO cell culture will facilitate the development of large-scale, high-yield fed-batch culture processes for the production of high-quality therapeutic proteins.

Bacterial community characterization of water and intestine of the shrimp Litopenaeus stylirostris in a biofloc system

BACKGROUND

Biofloc technology (BFT), a rearing method with little or no water exchange, is gaining popularity in aquaculture. In the water column, such systems develop conglomerates of microbes, algae and protozoa, together with detritus and dead organic particles. The intensive microbial community presents in these systems can be used as a pond water quality treatment system, and the microbial protein can serve as a feed additive. The current problem with BFT is the difficulty of controlling its bacterial community composition for both optimal water quality and optimal shrimp health. The main objective of the present study was to investigate microbial diversity of samples obtained from different culture environments (Biofloc technology and clear seawater) as well as from the intestines of shrimp reared in both environments through high-throughput sequencing technology.

RESULTS

Analyses of the bacterial community identified in water from BFT and "clear seawater" (CW) systems (control) containing the shrimp Litopenaeus stylirostris revealed large differences in the frequency distribution of operational taxonomic units (OTUs). Four out of the five most dominant bacterial communities were different in both culture methods. Bacteria found in great abundance in BFT have two principal characteristics: the need for an organic substrate or nitrogen sources to grow and the capacity to attach to surfaces and co-aggregate. A correlation was found between bacteria groups and physicochemical and biological parameters measured in rearing tanks. Moreover, rearing-water bacterial communities influenced the microbiota of shrimp. Indeed, the biofloc environment modified the shrimp intestine microbiota, as the low level (27 %) of similarity between intestinal bacterial communities from the two treatments.

CONCLUSION

This study provides the first information describing the complex biofloc microbial community, which can help to understand the environment-microbiota-host relationship in this rearing system.

[Investigation on Cheyletoidea mites breeding in culture environment of Eupolyphaga sinensis and morphologic observation of Eucheyletia reticulate Cunliffe]

OBJECTIVE

To investigate the species of Cheyletoidea mites breeding in the culture environment of Eupolyphaga sinensis and to observe the morphology of Eucheyletia reticulata Cunliffe.

METHODS

The soil samples from an E. sinensis farm in northern Anhui were collected. The mites in the soil samples were separated directly under a microscope and the glass specimens were made to observe the morphological feature of the mites under a light microscope, then the mites species were identified and classified based on the morphological characteristics.

RESULTS

In the culture soil of E. sinensis, totally 7 kinds of Cheyletoidea mites were isolated, namely Eucheyletia reticulata Cunliffe, Cheyletus eruditus Schrank, Cheyletus malaccensis Oudemans, Cheyletus troussarti Oudemans, Cheyletus aveisor Rohdendorz, Acaropsis sollers Rohdendorz and Cheletomorpha lepidopterorum Shaw. They belonged to genera Eucheyletia, Cheletomorpha, Acaropsis and Cheyletus of Cheyletidae Leach family. The Eucheyletia reticulata Cunliffe was firstly found in the culture environment of E. sinensis, and its gnathosoma was large, the pedipalpal femurs were expanding and there were two strips of comb hair and two smooth bristles on the pedipalpal tarsus, and the back of the body was covered with two pieces of tergum, which were decorated with reticular pattern. The body and foot setae were fan-shape.

CONCLUSIONS

There are various of Cheyletoidea mites found in the breeding environment of E. sinensis. These mites are important species for pest control in the culture environments of E. sinensis. Related measures should be taken to prevent the excessive growth of Cheyletoidea mites, so as to avoid the adverse effects on the quality and quantity of E. sinensis.

Effect of different culture systems on adipocyte differentiation-related protein (ADRP) in bovine embryos

Bovine embryos cultured in serum-containing media abnormally accumulate lipid droplets, compared to their in vivo counterparts. The objective of this study was to investigate the effect of different culture systems on the mRNA expression and on the quantification and localisation of adipocyte differentiation-related protein (ADRP), a protein associated with lipid accumulation in bovine blastocysts. Two experiments were independently performed for ADRP mRNA expression analysis. In experiment A, blastocysts were produced in modified synthetic oviduct fluid (mSOF)+10% foetal calf serum (FCS), in coculture (bovine oviduct epithelial cells, Boec) and in ewe oviducts, whereas in experiment B, they were produced in mSOF+10μM docosahexaenoic acid (DHA) and in vivo. Control groups were also performed. ADRP mRNA expression was downregulated in the Boec, ewe oviduct and in vivo groups compared to the 10% FCS or DHA groups, respectively. Moreover, the expression of this protein was downregulated in the Boec group compared to the control group (P<0.05). A third experiment (experiment C) was performed to quantify and localise ADRP protein. Boec, in vivo and control groups were tested. After immunofluorescence staining followed by confocal microscopy analysis, embryonic ADRP was clearly localised around lipid droplets, indicating that ADRP is also a lipid droplet coat protein in bovine embryos. In conclusion, our results demonstrate that bovine embryos at the blastocyst stage expressed ADRP mRNA and protein, and that the embryonic culture system modified this expression.