Celebrating 20 years of historical papers in Photosynthesis Research

This Editorial has four goals: (1) to inform the readers of ‘Photosynthesis Research‘ about the past of the ‘Historical corner’; which began 20 years ago; (2) to encourage photosynthesis researchers and historians of science to contact me for publishing papers of historical interest; these include: (a) Obituaries and Tributes; (b) historical papers on current and past discoveries and controversies; (c) history of research in specific laboratories, or in specific countries, or at specific conferences; (d) Personal perspectives (not discussed any further); (3) to encourage researchers not to discard, but to save correspondence and data of their discoveries for the future historians by donating them to their Archives, when appropriate (not discussed any further); and (4) to reinforce to the readers that the concept of two-light reaction and two-pigment system was already there in 1959. I mention here three key papers presented at the IX^th International Botanical Congress, held at Montreal Canada (in August, 1959) prior to the famous April 9, 1960 paper by Robert Hill and Fay Bendall on the ‘Z-scheme’ of photosynthesis, that was based on thermodynamic and energetic considerations. ^★ This Historical corner Editorial is dedicated to Bessel Kok (1918–1978).     

Downregulation of SIRT2 Inhibits Invasion of Hepatocellular Carcinoma by Inhibiting Energy Metabolism

Hepatocellular carcinoma (HCC) is one of the most common neoplasms, and metastasis is the most important feature for HCC-related deaths. Mounting evidence implies the dynamic regulatory role of SIRT2, a histone deacetylase, in cancer cells. Unfortunately, the role of SIRT2 and the antitumor activity of its inhibition are not known in HCC. The present study aims to evaluate the biological function of SIRT2 in HCC and identify the target of SIRT2 as well as evaluate its therapeutic efficacy. We found that SIRT2 was upregulated in HCC tissues compared to adjacent normal tissues, and this was correlated with reduced patient survival. Although CCK8 and colony-formation assays showed that SIRT2 inhibiton marginally promotes proliferation in HCC cell lines, SIRT2 knockdown decreased the invasion of HCC cells. We demonstrated that downregulation of SIRT2 could inhibit its downstream target phosphoenolpyruvate carboxykinase 1 and glutaminase, which is related to mitochondrial metabolism and the E-Cadherin pathway. These results demonstrate, for the first time that downregulation of SIRT2 decreases migration as well as invasion in human HCC cells, indicating that inhibiting SIRT2 may be an effective therapeutic strategy for treating HCC.     

The Romantic Conception of Robert J. Richards

In his new book, The RomanticConception of Life: Science and Philosophyin the Age of Goethe, Robert J. Richardsargues that Charles Darwin's trueevolutionary roots lie in the German Romanticbiology that flourished around thebeginning of the nineteenth century. It isargued that Richards is quite wrong in thisclaim and that Darwin's roots are in theBritish society within which he was born,educated, and lived.     

The use of dimenhydrinate in conjunction with dexamethasone for induction of parturition in beef cattle

Forty-eight crossbred Chianina cows (3 to 5 years of age), with an expected gestation length of 288 days, were randomly divided into four treatment groups to evaluate the use of dimenhydrinate (an antihistamine agent) in conjunction with dexamethasone (DEX) for inducing parturition in beef cattle. Group (A) received a 20 mg dose of DEX (im) on day 282 of gestation and a carrier vehicle (iv) 24 hours later (day 283); Group (B) was given a carrier vehicle (im) on day 282 and 500 mg of dimenhy-drinate (DMH) diluted in 200 ml of 2.5% dextrose-0.9% saline solution given (iv) on day 283 and Group (C) received 20 mg of DEX (im) on day 282 and 500 mg of DMH in solution (iv) on day 283 of gestation. The remaining 12 cows assigned to Group (D) were not handled and were allowed to calve under natural conditions. The number of cows calving and percent calving within 60 hours after the first injection were: 10(91%), none(0%) and 12(100%) for the DEX, DMH and DEX plus DMH groups, respectively. The mean gestation length of the control cows in Group (D) was 288.6 days. Frequency of dystocia was: 18.2, 8.3, 0 and 0% and retained placentae (>/=24 hours) was: 72.8, 16.6, 33.3 and 0% for DEX, DMH, DEX plus DMH and control groups, respectively. In this study, a 20 mg dose of DEX (im) followed 24 hours later with 500 mg of DMH (iv) was more successful for calving induction than when DEX or DMH was used alone. The combination DEX and DMH treatment induced calving in a shorter interval from treatment (P<.05) and decreased the incidence of retained placentae (P<.01) when compared with those induced following DEX treatment.     

On the transmission of external pressure fluctuations to the cerebrospinal fluid

A theory has been formulated to explain the manner in which external pressure fluctuations are transmitted to the cerebrospinal fluid (CSF). The theory is based upon a three-compartment model which consists of the cerebral ventricles, the basal cisterns and spinal subarachnoid space, and the cortical subarachnoid space. The external pressure disturbance is represented by a Fourier series summed over the frequency ω. The mathematical analysis leads to a time constant τ which depends upon the compliances of the spinal region and sources of external pressure fluctuations, the rate of CSF absorption and the rate of fluid transfer between compartments. For arterial pulsations where ωτ ? 1, the theory is in accord with the experimental observations that (i) the arterial and CSF pulse waves are nearly identical in shape, and (ii) the amplitude of the CSF pulse wave increases with intracranial pressure. Moreover, it predicts that the amplitude of the wave will be larger in the spinal region than in the ventricles. The theory also accounts for the observation of one per minute pulse waves observed in hydrocephalic patients with decreased absorption rates.     

The hydrolysis of α-amino-acid esters in mixed ligand complexes with copper(II)-iminodiacetate

α-Amino-acid esters (EH⁺) interact with [Cu(IMDA)]° to give mixed ligand complexes according to the equilibrium,

where EH⁺ represents the protonated ester ⁺NH₃CH(R)CO₂R′ and IMDA^2? is HN(CH₂CO_2^?)₂. The mixed ligand complexes are only formed over a rather narrow pH range (ca. pH 5.8–6.5). At higher pH there is kinetic evidence for the competing equilibrium,

Rate constants k_OH have been obtained by pH-stat for the hydrolyses [where A^? = NH₂CH(R)CO_2^?]

The complexed α-amino-acid esters undergo base hydrolysis ca. 10⁴ times faster than the free esters E. Values of k_OH show little dependence on the nature of the alkyl substituent R but the normal leaving group effect of methyl esters hydrolyzing at ca. twice the rate of ethyl esters is observed. Activation parameters have been determined for base hydrolysis of [Cu(IMDA)(glyOMe)]°, and possible mechanisms for the reaction are considered.     

Tobacco mosaic virus-enkephalin conjugates: potentiation of opioid activity

Covalent tobacco mosaic virus-enkephalin analogue conjugates containing between 5 and 450 agonist molecules attached through their C-terminal amino acids were prepared and assayed in pharmacological and binding assays that distinguish between mu- and delta-receptors. Increases in peptide- and receptor-specific potency and affinity were observed with a certain preference of mu- over delta-receptors. The results may become important for mapping receptors or for isolating opiate receptor-bearing membrane vesicles.     

Structure of the complex formed by bovine trypsin and bovine pancreatic trypsin inhibitor. Crystal structure determination and stereochemistry of the contact region

The structure of the complex of bovine trypsin and bovine pancreatic trypsin inhibitor has been determined by crystal structure analysis at 2.8 Å resolution. The structure is closely similar to the model predicted from the structures of the components. The complex is a tetrahedral adduct with a covalent bond between the carbonyl carbon of Lys-15I of the inhibitor and the γ-oxygen of Ser-195 of the enzyme. The imidazole of His-57 is hydrogen-bonded to Asp-102 and the bound seryl γ-oxygen in accord with the histidine being charged. The negatively charged carbonyl oxygen of Lys-15I forms two hydrogen bonds with the amide nitrogens of Gly-193 and Ser-195. Protonation of the leaving group N-H of Ala-16I to form an acyl-complex requires a conformational change of the imidazole of His-57. The tetrahedral adduct is further stabilized by hydrogen bonds between groups at the leaving group side and inhibitor and enzyme, which would be weakened in the acyl-enzyme. The kinetic data of inhibitor-enzyme interaction are reconciled with the structural model, and relations between enzyme-inhibitor interaction and productive enzyme-substrate interaction are proposed.     

Migration inhibitory factor (MIF) and proliferative responses by human lymphocyte subpopulations separated by sheep erythrocyte rosette formation.

Human peripheral blood lymphocytes were separated by a combination of rosette formation with sheep erythrocytes and differential density centrifugation into subpopulations of rosette positive (T-enriched) cells and rosette negative (T depleted) cells. These were then tested in vitro for the production of macrophage migration inhibitory factor (MIF) and for incorporation of ³H-thymidine in response to specific antigens. Both T enriched and T depleted cell populations produced MIF but only T enriched cells exhibited significant antigen-induced ³H-thymidine incorporation. These findings using a T cell surface marker as the basis for cell separation, a technique which should not alter the B cell surface, confirm an earlier report in which human cells were separated on the basis of surface immunoglobulin, a B cell marker.