A physiologically-oriented transcriptomic analysis of the midgut of Tenebrio molitor.
Physiological data showed that T. molitor midgut is buffered at pH 5.6 at the two anterior thirds and at 7.9 at the posterior third. Furthermore, water is absorbed and secreted at the anterior and posterior midgut, respectively, driving a midgut counter flux of fluid. To look for the molecular mechanisms underlying these phenomena and nutrient absorption as well, a transcriptomic approach was used. For this, 11 types of transporters were chosen from the midgut transcriptome obtained by pyrosequencing (Roche 454). After annotation with the aid of databanks and manual curation, the sequences were validated by RT-PCR. The expression level of each gene at anterior, middle and posterior midgut and carcass (larva less midgut) was evaluated by RNA-seq taking into account reference sequences based on 454 contigs and reads obtained by Illumina sequencing. The data showed that sugar and amino acid uniporters and symporters are expressed along the whole midgut. In the anterior midgut are found transporters for NH3and NH4+that with a chloride channel may be responsible for acidifying the lumen. At the posterior midgut, bicarbonate-Cl-antiporter with bicarbonate supplied by carbonic anhydrase may alkalinize the lumen. Water absorption caused mainly by an anterior Na+-K+-2Cl-symporter and water secretion caused by a posterior K+-Cl-may drive the midgut counter flux. Transporters that complement the action of those described were also found.
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil.
Nathalia R
NR
Moreira
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil.
Christiane
C
Cardoso
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil.
Renata O
RO
Dias
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil.
Clelia
C
Ferreira
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil. Electronic address: warterra@iq.usp.br.
Walter R
WR
Terra
D000596:Amino Acids / Q000378:metabolism; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001692:Biological Transport; D041981:Gastrointestinal Tract / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007814:Larva / Q000378:metabolism; D009005:Monosaccharides / Q000378:metabolism; D013712:Tenebrio / Q000254:growth & development / Q000378:metabolism*; D014867:Water / Q000378:metabolism
D000596:Amino Acids; D009005:Monosaccharides; D014867:Water
Ion transporters; Midgut buffering; Midgut counter fluxes; Midgut transporters; Nutrient absorption