Citation:

srep10421

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Abstract:

The stomachs of most vertebrates operate at an acidic pH of 2 generated by the gastric H+/K+-ATPase located in parietal cells. The acidic pH in stomachs of vertebrates is believed to aid digestion and to protect against environmental pathogens. Little attention has been placed on whether acidic gastric pH regulation is a vertebrate character or a deuterostome ancestral trait. Here, we report alkaline conditions up to pH 10.5 in the larval digestive systems of ambulacraria (echinoderm + hemichordate), the closest relative of the chordate. Microelectrode measurements in combination with specific inhibitors for acid-base transporters and ion pumps demonstrated that the gastric alkalization machinery in sea urchin larvae is mainly based on direct H+ secretion from the stomach lumen and involves a conserved set of ion pumps and transporters. Hemichordate larvae additionally utilized HCO3- transport pathways to generate even more alkaline digestive conditions. Molecular analyses in combination with acidification experiments supported these findings and identified genes coding for ion pumps energizing gastric alkalization. Given that insect larval guts were also reported to be alkaline, our discovery raises the hypothesis that the bilaterian ancestor utilized alkaline digestive system while the vertebrate lineage has evolved a strategy to strongly acidify their stomachs.

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Comment
1	Table	Tab		Stumpp, Meike
2	Figure	Fig		Stumpp, Meike
3	Experimental treatment	Exp treat		Stumpp, Meike
4	Species	Species		Stumpp, Meike
5	Description	Description		Stumpp, Meike	number of replicates
6	pH	pH		Stumpp, Meike
7	pH, standard deviation	pH std dev	±	Stumpp, Meike
8	Alkalinity, total	AT	mmol(eq)/l	Stumpp, Meike
9	Alkalinity, total, standard deviation	AT std dev	±	Stumpp, Meike
10	Carbon dioxide, partial pressure	pCO2	µatm	Stumpp, Meike
11	Carbon dioxide, partial pressure, standard deviation	pCO2 std dev	±	Stumpp, Meike
12	Carbon, inorganic, dissolved	DIC	mmol/l	Stumpp, Meike
13	Carbon, inorganic, dissolved, standard deviation	DIC std dev	±	Stumpp, Meike
14	Temperature, water	Temp	°C	Stumpp, Meike
15	Salinity	Sal		Stumpp, Meike
16	Inhibition of gastric alkalization	Inhib gastric alkal	%	Stumpp, Meike	mean
17	Standard error	Std e	±	Stumpp, Meike	mean, inhibition of gastric alkalization
18	Gene name	Gene		Stumpp, Meike
19	Gene expression, fold change, relative	Gene expression		Stumpp, Meike	mean log2-fold change
20	Gene expression, fold change, relative, standard error	Gene expression std e	±	Stumpp, Meike	mean

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

208 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Tab	2 Fig	3 Exp treat	4 Species	5 Description	6 pH	7 pH std dev [±]	8 AT [mmol(eq)/l]	9 AT std dev [±]	10 pCO2 [µatm]	11 pCO2 std dev [±]	12 DIC [mmol/l]	13 DIC std dev [±]	14 Temp [°C]	15 Sal	16 Inhib gastric alkal [%]	17 Std e [±]	18 Gene	19 Gene expression	20 Gene expression std e [±]
S1		pH=8.1	Strongylocentrotus purpuratus		8.04	0.010	2.02	0.10	489	16	1.89	0.09	14	31
S1		pH=7.0	Strongylocentrotus purpuratus		6.98	0.020	2.06	0.01	6456	482	2.30	0.10	14	31
S1		pH=8.2	Ptychodera flava		8.25	0.002	2.21	0.02	332	4	1.91	0.02	25	31
S1		pH=7.0	Ptychodera flava		6.99	0.015	2.20	0.02	7683	265	2.40	0.01	25	31
	1D	Ouabain (OUA)	Strongylocentrotus purpuratus	5-7											30.3999	18.1418
	1D	Bafilomycin (BAF)	Strongylocentrotus purpuratus	5-7											34.4130	8.2839
	1D	Omeprazole (OMZ)	Strongylocentrotus purpuratus	5-7											4.8339	7.7912
	1D	Ethyl-isopropyl amilorid (EIPA)	Strongylocentrotus purpuratus	5-7											40.4475	4.0980
	1D	4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS)	Strongylocentrotus purpuratus	5-7											-7.9656	4.6161
	1D	Acetazolamide (ACZ)	Strongylocentrotus purpuratus	5-7											2.6001	2.9741
	1D	Ouabain (OUA)	Ptychodera flava	5-7											6.4675	2.9973
	1D	Bafilomycin (BAF)	Ptychodera flava	5-7											2.0095	0.7472
	1D	Omeprazole (OMZ)	Ptychodera flava	5-7											20.9831	7.9124
	1D	Ethyl-isopropyl amilorid (EIPA)	Ptychodera flava	5-7											6.9516	2.1299
	1D	4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS)	Ptychodera flava	5-7											12.9380	3.0399
	1D	Acetazolamide (ACZ)	Ptychodera flava	5-7											13.4370	10.6643
	2A		Strongylocentrotus purpuratus	4-5													Na+/K+-ATPase (NKA)	5.0906	0.0924
	2A		Strongylocentrotus purpuratus	4-5													Na+/H+-exchanger 3 (NHE3)	7.2421	0.1510
	2A		Strongylocentrotus purpuratus	4-5													V-type H+-ATPase (VHA)	6.6771	0.1156
	2A		Strongylocentrotus purpuratus	4-5													transmembrane and coiled-coil domains 3 (Tmco3) (KHE)	12.5718	0.0377
	2A		Strongylocentrotus purpuratus	4-5													Na+/HCO3- cotransporter (NBC3)	1.4569	0.3446
	2A		Strongylocentrotus purpuratus	4-5													Cl-/HCO3- exchanger 2 (AE2)	0.8491	0.1607
	2A		Strongylocentrotus purpuratus	4-5													Carbonic anhydrase (CA)	1.2480	0.2218
	2B		Ptychodera flava	4-5													Na+/K+-ATPase (NKA)	3.0686	0.0814
	2B		Ptychodera flava	4-5													Na+/H+-exchanger 3 (NHE3)	3.9141	0.0775
	2B		Ptychodera flava	4-5													V-type H+-ATPase (VHA)	0.9322	0.1855
	2B		Ptychodera flava	4-5													transmembrane and coiled-coil domains 3 (Tmco3) (KHE)	0.0000	0.0000
	2B		Ptychodera flava	4-5													Na+/HCO3- cotransporter (NBC3)	4.3312	0.1575
	2B		Ptychodera flava	4-5													Cl-/HCO3- exchanger 2 (AE2)	1.3870	0.1229
	2B		Ptychodera flava	4-5													Carbonic anhydrase (CA)	2.8438	0.1035