The responses of germ-free zebrafish (Danio rerio) to varying bacterial concentrations, colonization time points and exposure duration. Frontiers in Microbiology 10; Article 2156; 1 - 13.
Loading...
Date
2019-09-18
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers Media SA
Abstract
Colonizing germ-free (GF) zebrafish with specific bacterial species provides the
possibility of understanding the influence on host biological processes including gene
expression, development, immunity, and behavioral responses. It also enlightens our
understanding on the host-microbe interactions within the physiological context of a
living host. However, the responses of GF zebrafish to various colonization conditions
such as bacterial concentrations, colonization time points, and exposure duration
remain unclear. To address this issue, we explored the responses of GF zebrafish by
using two bacterial species at varying concentrations, colonization time points and
exposure duration. Therefore, we mono-associated GF zebrafish with Escherichia coli
DH5α or Bacillus subtilis WB800N at concentrations ranging from 102
to 107 CFU/ml
either at 3 day post fertilization (dpf) or 5 dpf for 24 or 48 h. We evaluated the
responses of GF zebrafish by analyzing the survival rate, colonization efficiency, nutrients
metabolism, intestinal cell proliferation, innate immunity, stress, and behavior responses
by comparing it to conventionally raised zebrafish (CONR) and GF zebrafish. The results
indicated that the final bacteria concentrations ranging from 102
to 104 CFU/ml did
not cause any mortality when GF mono-associated larvae were exposed to either
E. coli DH5α or B. subtilis WB800N at 3 or 5 dpf, while concentrations ranging
from 106
to 107 CFU/ml increased the mortality, particularly for 5 dpf owing to the
decrease in dissolved oxygen level. The E. coli DH5α mainly induced the expression of
genes related to nutrients metabolism, cell proliferation and immunity, while B. subtilis
WB800N mainly upregulated the expression of genes related to immunity and stress
responses. Moreover, our data revealed that GF zebrafish showed higher levels of
physical activity than CONR and the microbial colonization reduced the hyperactivity
of GF zebrafish, suggesting colonization of bacteria affected behavior characteristics.
This study provides useful information on bacterial colonization of GF zebrafish and the
interaction between the host and microbiota.
Description
Keywords
germ-free zebrafish; colonization conditions; host responses; gnotobiotic zebrafish; host microbiota; mono-association
Citation
Fang Tan, Samwel Mchele Limbu, Ye Qian, Fang Qiao, Zhen-Yu Du and Meiling Zhang (2019). The responses of germ-free zebrafish (Danio rerio) to varying bacterial concentrations, colonization time points and exposure duration. Frontiers in Microbiology 10; Article 2156; 1 - 13. https://doi.org/10.3389/fmicb.2019.02156