Lincoln Taiz | University of California, Santa Cruz (original) (raw)

Papers by Lincoln Taiz

American Journal of Botany, 1973

... LINCOLN TAIZ AND RUSSELL L. JONES Department of Botany, University of California, Berkeley 94... more ... LINCOLN TAIZ AND RUSSELL L. JONES Department of Botany, University of California, Berkeley 94720 ... cell walls for microscopy-Isolated aleurone layers were blended in an Omnimixer (Ivan Sorvall Inc., Conn.) at half maximum speed for 2 min to re-move the testa-pericarps. ...

Plant Physiology, Dec 1, 1987

ABSTRACI A tonoplast enriched fraction was obtained from Zea mays L. coleoptiles by isopycnic cen... more ABSTRACI A tonoplast enriched fraction was obtained from Zea mays L. coleoptiles by isopycnic centrifuption of microsomal membranes in a sucrose step gradient. At the 18/26% interface chloride-stimulated and nitrateinhibited proton pumping activity coincided with a Mg2"-ATP dependent

Protoplasma, Nov 16, 2020

Claims that plants have conscious experiences have increased in recent years and have received wi... more Claims that plants have conscious experiences have increased in recent years and have received wide coverage, from the popular media to scientific journals. Such claims are misleading and have the potential to misdirect funding and governmental policy decisions. After defining basic, primary consciousness, we provide new arguments against 12 core claims made by the proponents of plant consciousness. Three important new conclusions of our study are (1) plants have not been shown to perform the proactive, anticipatory behaviors associated with consciousness, but only to sense and follow stimulus trails reactively; (2) electrophysiological signaling in plants serves immediate physiological functions rather than integrative-information processing as in nervous systems of animals, giving no indication of plant consciousness; (3) the controversial claim of classical Pavlovian learning in plants, even if correct, is irrelevant because this type of learning does not require consciousness. Finally, we present our own hypothesis, based on two logical assumptions, concerning which organisms possess consciousness. Our first assumption is that affective (emotional) consciousness is marked by an advanced capacity for operant learning about rewards and punishments. Our second assumption is that image-based conscious experience is marked by demonstrably mapped representations of the external environment within the body. Certain animals fit both of these criteria, but plants fit neither. We conclude that claims for plant consciousness are highly speculative and lack sound scientific support.

Journal of Theoretical Biology, Nov 1, 1986

... LINCOLN TAIZ Biology Department, Thimann Laboratories, University of California, Santa Cruz, ... more ... LINCOLN TAIZ Biology Department, Thimann Laboratories, University of California, Santa Cruz, Santa Cruz, CA 95064, USA (Received 2 May 1986, and in revised form 13 ... Halophytes may take up sodium into vacuoles via specific Na /H antiporters (Blumwald & Poole, 1985). ...

Botanica acta, Apr 1, 1991

Eukaryotic vacuolar H+-ATPases (V-ATPases) are related to the FoFl-ATPases of chloroplasts and mi... more Eukaryotic vacuolar H+-ATPases (V-ATPases) are related to the FoFl-ATPases of chloroplasts and mitochondria and are believed to be organized into peripheral and integral membrane complexes. Vacuolar membranes isolated from purified carrot (Daucus carota) root vacuoles were observed to be coated with F1-like particles after negative staining with phosphotungstic acid. The F,-like particles formed typical "ball and stalk" structures, about 9.4 nm in diameter and 13.6nm in height. The head portion frequently had a characteristic bifurcation or cleft at the apex and appeared to be composed of subunits. Such "VI" complexes were frequently associated with smaller stalked particles emerging near the base. In contrast, negatively-stained carrot mitochondrial F1 complexes averaged 8.7 nm in diameter and 11.7 nm in height. The head groups of the mitochondrial Fls were nearly always spherical, and had no other smaller structures associated with them. The V1 complexes of carrot are thus similar in form to the V1 complexes of Neurospora (Bowman et al.

FEBS Letters, 1990

In the evolution of the F,Ft family of proton-translacating membrane complexes, two reversals in ... more In the evolution of the F,Ft family of proton-translacating membrane complexes, two reversals in function appear to have occurred, first changing it from an ATPase to an ATP synthase and then back again to an ATPase. Here we suggest that with each change In function, the ratio of protons transported per ATP hydrolyzed or synthesized (H+/ATP) was altered in order for the complex to better adapt to its new role. We propose that this was accomplished by gene duplication with partial loss in the number of functional catalytic sites (to increase H+/ATP) or functional proton channels (to decrease H+/ATP). This method of changing the H+fAfP ratio preserved overah structural features of the complex essential to energy coupling.

Proceedings of the National Academy of Sciences of the United States of America, 1986

The H+-translocating ATPase located on vacuolar membranes of Neurospora crassa was partially puri... more The H+-translocating ATPase located on vacuolar membranes of Neurospora crassa was partially purified by solubilization in two detergents, Triton X-100 and N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, followed by centrifugation on sucrose density gradients. Two polypeptides ofMr-70,000 and "'62,000 consistently migrated with activity, along with several minor bands of lower molecular weight. Radioactively labeled inhibitors of ATPase activity, N-['4C]ethylmaleimide and 7-chloro-4-nitro[(4C~benzo-2oxa-1,3-diazole, labeled the Mr w70,000 polypeptide; this labeling was reduced in the presence of ATP. NN'-[14C]dicyclohexylcarbodiimide labeled a polypeptide of Mr ""15,000. Estimation of the functional size of the vacuolar membrane ATPase by radiation inactivation gave a value of Mr 5.2 x 10, 10-15% larger than the mitochondrial ATPase. The Neurospora vacuolar ATPase showed no crossreactivity with antiserum to plasma membrane or mitochondrial ATPase but strongly crossreacted with antiserum against a polypeptide of Mr w70,000 associated with the tonoplast ATPase of corn coleoptiles. These results suggest that fungal and plant vacuolar ATPases may be large multisubunit complexes, somewhat similar to, but immunologically distinct from, known FoF1 ATPases.

Journal of Biological Chemistry, Jul 1, 1988

Plant Physiology, Dec 1, 1982

Planta, 1970

A glucanase from barley aleurone layers can be assayed using the algal polysaccharide laminarin a... more A glucanase from barley aleurone layers can be assayed using the algal polysaccharide laminarin as substrate. Gibberellic acid (GA3) enhances the release of this enzyme from isolated aleurone layers but has no significant effect on its synthesis. Concentrations of GA3 effective in stimulating this release are in the range of 3×10(-11)-3×10(-7)M. The time course of glucanase release was found to be significantly different from that of α-amylase, glucanase release being completed before that of α-amylase. Evidence based on using various histochemical stains suggests that barley aleurone cell walls contain a β-1,3-linked polymer. Following treatment of aleurone layers with GA3, digestion of these walls is seen to occur. These observations strongly suggest that the β-1,3-glucanase produced by aleurone cells is resposible for the observed cell-wall digestion.

Journal of Biological Chemistry, Sep 1, 1986

Gradient purified preparations of the maize 400-kDa tonoplast ATPase are enriched in two major po... more Gradient purified preparations of the maize 400-kDa tonoplast ATPase are enriched in two major polypeptides, 72 and 62 kDa. Polyclonal antibodies were prepared against these two putative subunits after elution from sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel slices and against the solubilized native enzyme. Antibodies to both the 72-and 62-kDa polypeptides cross-reacted with similar bands on immunoblots of a tonoplast-enriched fraction from barley, while only the 72-kDa antibodies cross-reacted with tonoplast and tonoplast ATPase preparations from Neurospora. Antibodies to the 72-kDa polypeptide and the native enzyme both strongly inhibited enzyme activity, but the 62-kDa antibody was without effect. The identity and function of the subunits was further probed using radiolabeled covalent inhibitors of the tonoplast ATPase, 7-chloro-4-nitro['4C]benzo-2-oxa-1,3-diazole (['4C]NBD-Cl) and N,N'-['4C]dicyclohexylcarbodiimide ([14C]DCCD). [14C]NBD-C1 preferentially labeled the 72-kDa polypeptide, and labeling was prevented by ATP. [14C]DCCD, an inhibitor of the proton channel portion of the mitochondrial ATPase, bound to a 16-kDa polypeptide. Venturicidin blocked binding to the mitochondrial 8-kDa polypeptide but did not affect binding to the tonoplast 16-kDa polypeptide. Taken together, the results implicate the 72-kDa polypeptide as the catalytic subunit of the tonoplast ATPase. The DCCD-binding 16-kDa polypeptide may comprise the proton channel. The presence of nucleotide-binding sites on the 62-kDa polypeptide suggests that it may function as a regulatory subunit. Plant vacuoles are acidic organelles in which ions, sugars, organic acids, and hydrolytic enzymes are stored (1). Studies with isolated vacuoles and tonoplast (plant vacuolar membrane) vesicles have indicated that a proton-translocating ATPase present on the tonoplast generates an electrochemical gradient, which may be responsible for the observed accumulation of ions and solutes (reviewed in Ref. 2). A similar ATP-dependent proton pump is also present on the Golgi of maize coleoptiles (3). Several recent reports have described the partial purification of a novel ATPase from plant and ~~

The Journal of Experimental Biology, Nov 1, 1992

Plant cells are unique in containing large acidic vacuoles which occupy most of the cell volume. ... more Plant cells are unique in containing large acidic vacuoles which occupy most of the cell volume. The vacuolar H +-ATPase (V-ATPase) is the enzyme responsible for acidifying the central vacuole, although it is also present on Golgi and coated vesicles. Many secondary transport processes are driven by the proton-motive force generated by the V-ATPase, including reactions required for osmoregulation, homeostasis, storage, plant defense and many other functions. However, a second proton pump, the V-PPase, serves as a potential backup system and may, in addition, pump potassium. The plant V-ATPase is structurally similar to other eukaryotic V-ATPases and its subunits appear to be encoded by small multigene families. These multigene families may play important roles in the regulation of gene expression and in the sorting of V-ATPase isoforms to different organelles.

Animal Sentience: An Interdisciplinary Journal on Animal Feeling, Apr 28, 2023

Segundo-Ortin & Calvo's (2023) target article takes a less speculative and more evidence-based ap... more Segundo-Ortin & Calvo's (2023) target article takes a less speculative and more evidence-based approach to plant sentience than did previous works promoting that idea. However, it retains many of the idea's longstanding difficulties such as starting from a false dichotomy (plants must be either hardwired or sentient), not accepting the full burden of proof for an extraordinary claim, confusingly redefining accepted cognitive terms, implying cell consciousness, not adopting the most parsimonious explanations for plant behaviors, and downplaying all the counterevidence. We advise rectifying these problems before plant sentience can become a full-fledged scientific domain.

Plant Physiology, Oct 1, 1998

The spatial and temporal expression patterns of metallothionein (MT) isoforms MT1a and MT2a were ... more The spatial and temporal expression patterns of metallothionein (MT) isoforms MT1a and MT2a were investigated in vegetative and reproductive tissues of untreated and copper-treated Arabidopsis by in situ hybridization and by northern blotting. In control plants, MT1a mRNA was localized in leaf trichomes and in the vascular tissue in leaves, roots, flowers, and germinating embryos. In copper-treated plants, MT1a expression was also observed in the leaf mesophyll and in vascular tissue of developing siliques and seeds. In contrast, MT2a was expressed primarily in the trichomes of both untreated and copper-treated plants. In copper-treated plants, MT2a mRNA was also expressed in siliques. Northern-hybridization studies performed on developing seedlings and leaves showed temporal variations of MT1a gene expression but not of MT2a expression. The possible implications of these findings for the cellular roles of MTs in plants are discussed.

Journal of Bioenergetics and Biomembranes, Aug 1, 1992

Proton pumping ATPases/ATPsynthases are found in all groups of present-day organisms. The structu... more Proton pumping ATPases/ATPsynthases are found in all groups of present-day organisms. The structure of V-and F-type ATPases/ATP synthases is very conserved throughout evolution. Sequence analysis shows that the V-and F-type ATPases evolved from the same enzyme already present in the last common ancestor of all known extant life forms. The catalytic and noncatalytic subunits found in the dissociable head groups of the V/F-type ATPases are paralogous subunits, i.e., these two types of subunits evolved from a common ancestral gene. The gene duplication giving rise to these two genes (i.e., encoding the catalytic and noncatalytic subunits) predates the time of the last common ancestor. Mapping of gene duplication events that occurred in the evolution of the proteolipid, the noncatalytic and the catalytic subunits, onto the tree of life leads to a prediction for the likely subunit structure of the encoded ATPases. A correlation between structure and function of V/F-ATPases has been established for present-day organisms. Implications resulting from this correlation for the bioenergetics operative in proto-eukaryotes and in the last common ancestor are presented. The similarities of the V/F-ATPase subunits to an ATPase-like protein that was implicated to play a role in flagellar assembly are evaluated. Different V-ATPase isoforms have been detected in some higher eukaryotes. These data are analyzed with respect to the possible function of the different isoforms (tissue specific, organelle specific) and with respect to the point in their evolution when these gene duplications giving rise to the isoforms had occurred, i.e., how far these isoforms are distributed.

Trends in Biochemical Sciences, Mar 1, 1989