25 research outputs found
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
p-Aminohippurate/2-oxoglutarate exchange in bovine renal brush-border and basolateral membrane vesicles
The transport of the amphiphilic organic anion, P-aminohippurate (PAH), across the luminal (brush-border) and contraluminal (basolateral) membrane of renal proximal tubule cells was studied with membrane vesicles isolated from bovine kidney cortex. On the basis of the enrichment of specific activities of marker enzymes, leucine aminopeptidase and Na+/K+-ATPase, brush-border and basolateral membrane vesicles can be obtained from bovine kidneys in reasonably pure form. The uptake of [3H]PAH into both brush-border and basolateral membrane vesicles was trans-stimulated by intravesicular PAH and by 2-oxoglutarate. In the absence of Na+, [3H]PAH/2-oxoglutarate exchange was cis-inhibited by unlabelled 2-oxoglutarate in the medium. In the presence of an inward Na+ gradient, 10 ÎŒM 2-oxoglutarate, but no other Krebs cycle derivative, cis-stimulated [3H]PAH uptake, indicating that a Na+-coupled dicarboxylate transporter and PAH/2-oxoglutarate exchanger cooperate in both membranes to enhance [3H]PAH uptake. [3H]PAH uptake showed a non-saturable and a saturable component with similar apparent Km values in brush-border and basolateral membranes. Although one negatively charged PAH molecule exchanges with one doubly negatively charged 2-oxoglutarate molecule the exchange was electroneutral. Probenecid inhibited [3H]PAH/2-oxoglutarate exchange in brush-border and basolateral membrane vesicles with indistinguishable kinetics. We conclude that similar or identical PAH transporters are located in brush-border and basolateral membranes of bovine kidney proximal tubule cells. This arrangement seems species-specific since a Na+ gradient plus 2-oxoglutarate caused concentrative [3H]PAH uptake in brush-border membrane vesicles from bovine, but not from rat kidney
Modulation by anions of p-aminohippurate transport in bovine renal basolateral membrane vesicles
In the presence of 10 ÎŒM 2-oxoglutarate (2-OG) and of an inward Na+ gradient, uphill [3H]p-aminohippurate (PAH) uptake occurs due to cooperation of the PAH/2-OG exchanger and the Na+-coupled 2-OG transporter in bovine renal basolateral membrane vesicles. Uphill PAH uptake is observed with Clâ, but not with gluconate as the bulk anion. To determine specificity and nature of this anion effect [3H]PAH uptake was measured in the presence of several anions without and with ionophores to distinguish indirect from direct effects on the PAH transporter. Na+-gradient plus 2-OGstimulated [3H]PAH uptake is fast with Clâ, intermediate with Fâ, Brâ, Iâ, NO3â and SCNâ, and slow in the presence of gluconate, SO42â and HPO42â. Stimulation by Clâ (as compared to gluconate) is attenuated, but not abolished, by clamping electrical potential and pH differences to zero, suggesting a partial effect through charge compensation and a major effect of anions on the PAH transporter itself. Indeed, [3H]PAH/2-OG and [3H]PAH/ PAH exchange rates under voltage- and pH-clamped condition depend on bulk anions although the anion effects are less pronounced than with Na+-gradient plus 2-OG-stimulated [3H]PAH uptake. Since an inward Clâ gradient does not drive [3H]PAH above or below equilibrium distribution, Clâ ions are most probably not translocated by the PAH transporter. We propose that anions modulate the PAH transporter by interacting with a site not directly related to anion transport