A biographical sketch of Charles F. Yocum: “It's the biochemistry, stupid”

Charles F. Yocum has been a leader in the applications of biochemical techniques to the resolution and reconstitution of Photosystem II. His formal science education began as an undergraduate in biochemistry at Iowa State University and continued with graduate work in photosynthesis, first at the Illinois Institute of Technology and later at Indiana University. Following postdoctoral work at Cornell University, he joined the faculty of the University of Michigan where he has remained throughout his academic career. Charlie's contributions to a biochemical understanding of photosynthesis, particularly Photosystem II have been considerable, but most notably include his initial isolation of the first highly active oxygen-evolving particle from higher plant chloroplasts, the well-known and widely utilized `BBY particles'. In the aftermath of that isolation, Charlie's research further resolved these particles into ever finer and simpler, but active, Photosystem II complexes. In addition, Charlie's research has provided significant insight into the roles of both Cl⁻ and Ca²⁺ as required cofactors in photosynthetic oxygen evolution. This revised version was published online in June 2006 with corrections to the Cover Date.     

A tribute to Thomas Roosevelt Punnett, Jr. (1926-2008)

We honor here Thomas (Tom) Roosevelt Punnett, Jr. (May 25, 1926–July 4, 2008), who was a pioneer of Biology, particularly of biochemistry of plants and algae, having specialized in photosynthesis under Robert Emerson of the University of Illinois at Urbana-Champaign. He did exciting work on regulation and control of various metabolic reactions. He was an innovator and raconteur par excellence, and he prized critical thinking. His enthusiasm for basic science questions was matched by his grasp of their “real-world” implications. His last project was a patent for anaerobic sewage treatment that he hoped would lead to solution of waste disposal and energy creation world wide, including the clean-up of Lake Erie, where he had sailed as a boy. On the personal side, he had a strong sense of morality and a great wit and humor.     

From intestine transport to enzymatic regulation: The works of the Spanish biochemist Alberto Sols (1917–1989)

In this paper the scientific trajectory of Spanish influential biochemist Alberto Sols (1917–1989) is presented in comparative perspective. His social and academic environment, his research training under the Cori's in the US in the early 1950s and his works when coming back to Spain to develop his own scientific career are described in order to present the central argument of this paper on his path from physiological research to research on enzymatic regulation. Sols' main contributions were both scientific and academic. He and his collaborators not only contributed to biological knowledge on the biochemistry of metabolic regulation but to the active reception of biochemistry in the Spanish academia and to update of Spanish medical education.     

Joseph Dalton Hooker's Ideals for a Professional Man of Science

During the 1840s and the 1850s botanist Joseph Hooker developeddistinct notions about the proper characteristics of aprofessional man of science. While he never articulated theseideas publicly as a coherent agenda, he did share his opinionsopenly in letters to family and colleagues; this privatecommunication gives essential insight into his and his X-Clubcolleagues' public activities. The core aspiration of Hooker'sprofessionalization was to consolidate men of science into adutiful and centralized community dedicated to nationalwell-being. The nation in turn owed the scientific community forits ministration. When the government bestowed funds and statuson men of science it was rewarding science – not purchasing it. His proposed reforms were piecemeal, immediate, and above allpractical. He harbored no taste for vast millenariantransformation, and rested his conception of scientificprofessionalism upon a respectable High Victorian foundation ofpatronage and pillars of duty, reciprocity, intimacy, andinequality. The process of professionalization he envisioned wasas much shrewd compromise between existing interests as avindication of principle. His power and prestige from themid-1850s onward gave him considerable ability to carry out hisreform program, although his general success did occasion someundesired consequences for the status of natural-historypursuits. This revised version was published online in July 2006 with corrections to the Cover Date.     

Don C. Ohadike: The Man, his Intellectual Legacy and African Historiography

It is difficult to completely understand the life history of an intellectual excluding an understanding of his family upbringing and formative years. Family upbringing and childhood environment, often the less known part of a life history, play crucial roles in shaping the ideas and values individuals espouse in their adult life. Notwithstanding, this paper is not concerned with Don C. Ohadike’s childhood. It rather focuses on the professional career of our able historian – that is the part of his life as revealed by his most outstanding published writings. Ohadike’s published works contain a wellspring of idioms that tell much about his values, quality of mind, and his mission as an African historian. Ohadike was a humanist, an African patriot, and a nationalist crusader. His entire philosophy centered on safeguarding his African identity in an emergent world of cultural imperialism. The funds for this research were provided by a NEH-funded fellowship at the Schomburg Center, New York in the Spring of 2007. I owe a lot of gratitude to Professor John McLeod and Dean Blaine Hudson for granting me the extra incentives to pursue my research in New York. While all errors and misinterpretations are mine, I wish to thank the editors and anonymous reviewers for Journal of Dialectical Anthropology for their perspective comments and suggestions on earlier drafts of this paper.     

Micromechanics and anatomical changes during early ontogeny of two lianescent Aristolochia species

 The mechanical properties of young stems of Aristolochia macrophylla Lam. and Aristolochia brasiliensis Mart. et Zucc. were studied during elongation growth and primary differentiation. Data for the modulus of elasticity, for the viscoelastic behaviour caused by longitudinal tension and for the shear modulus resulting from torsion around a longitudinal axis were related to the underlying structural changes by quantitative analysis of stem anatomy, tissue distribution, ultrastructure, and cell wall biochemistry. The orientation of cellulose microfibrils was determined by light microscopy and small-angle X-ray diffraction, and the lignin content was determined by thioglycolic acid derivatization and spectroscopic quantification. It was demonstrated that the increase in stability during early development is due to the complementary effects of increase in cell wall material, lignification, and cellulose microfibril alignment. A detailed micromechanical model, considering internal prestresses, is proposed to explain the characteristic biphasic stress-strain behaviour as well as the strain-hardening observed. Received: 22 March 1999 / Accepted 9 September 1999     

Spatial and temporal expression profiles suggest the involvement of gelatinase A and membrane type 1 matrix metalloproteinase in amphibian metamorphosis

The matrix metalloproteinases (MMPs) are a family of proteases capable of degrading various components of the extracellular matrix (ECM). Among them, the membrane type MMP–1 (MT1–MMP) has been shown to participate in the activation of MMP gelatinase A (GelA), suggesting that they may function together in development and pathogenesis. Here, we have investigated the spatiotemporal expression profiles of Xenopus laevis MT1–MMP and GelA genes during thyroid-hormone-dependent metamorphosis. We have focused our studies on two organs: (1) the intestine, which undergoes first the degeneration of the tadpole epithelium through apoptosis and then the development of adult epithelium and other tissues, and (2) the tail, which completely resorbs through programmed cell death. We show that both MT1–MMP and GelA are upregulated in the intestine and tail when both organs undergo metamorphosis. Within the organs, MT1–MMP and GelA are coexpressed in the connective tissues during both natural and thyroid-hormone-induced metamorphosis. In addition, MT1–MMP (but not GelA) is also expressed in the longitudinal muscle cells of the metamorphosing intestine. These results suggest that MT1–MMP and GelA function together in the ECM degradation or remodeling associated with metamorphosis and that MT1–MMP has additional GelA–independent roles in the development of adult longitudinal muscle in the intestine. This research was supported by the Intramural Research Program of the National Institute of Child Health and Human Development, NIH. T. Hasebe and H. Matsuda were supported in part by JSPS (NIH) fellowships.     

A DEFICIENS homologue is down-regulated during apomictic initiation in ovules of Hieracium

 Hieracium is a member of the Asteraceae family, and contains sexual species in addition to apomictic species that reproduce by apospory and produce seed without fertilization. A homologue of the floral organ-identity gene DEFICIENS (DEF) was isolated from an apomictic line of Hieracium piloselloides (Vill.) following differential display between mature ovules and those initiating autonomous embryogenesis. The gene termed HPDEF has 93% amino acid identity with GDEF2, a DEF homologue isolated from Gerbera hybrida (D. Yu et al., 1999, Plant J. 17: 51–62), another member of the Asteraceae. In-situ analysis showed that early in floral development HPDEF is expressed in stamen and petal primordia, indicating expected B-function activity, according to the ABC model of floral organ identity (J. L. Bowman et al., 1991, Development 112: 1–20; E. S. Coen and E. M. Meyerowitz, 1991, Nature 353: 31–37). However, HPDEF expression was also observed in ovule primordia and expression continued in developing ovules until anthesis, indicating that this gene may have a role in ovule development. Expression of HPDEF was not detected in megaspore mother cells, or in sexual or aposporous embryo sacs. In sexual Hieracium, HPDEF was uniformly expressed throughout the ovule integument until anthesis. In most ovules of the apomict, however, HPDEF expression was transiently down-regulated in a specific zone in the chalazal region where cells initiating aposporous embryo sac formation differentiate. Uniform low-level HPDEF expression was subsequently observed prior to anthesis in ovules from sexual and apomictic plants. HPDEF may be down-regulated as a consequence of apomictic initiation and/or its down-regulation may facilitate progression of apomictic events. Received: 15 September 1999 / Accepted: 12 October 1999     

Abscisic acid and hydraulic conductivity of maize roots: a study using cell- and root-pressure probes

Using root- and cell-pressure probes, the effects of the stress hormone abscisic acid (ABA) on the water-transport properties of maize roots (Zea mays L.) were examined in order to work out dose and time responses for root hydraulic conductivity. Abscisic acid applied at concentrations of 100–1,000 nM increased the hydraulic conductivity of excised maize roots both at the organ (root Lp_r: factor of 3–4) and the root cell level (cell Lp: factor of 7–27). Effects on the root cortical cells were more pronounced than at the organ level. From the results it was concluded that ABA acts at the plasmalemma, presumably by an interaction with water channels. Abscisic acid therefore facilitated the cell-to-cell component of transport of water across the root cylinder. Effects on cell Lp were transient and highly specific for the undissociated (+)-cis-trans-ABA. The stress hormone ABA facilitates water uptake into roots as soils start drying, especially under non-transpiring conditions, when the apoplastic path of water transport is largely excluded. Received: 26 February 2000 / Accepted: 17 August 2000     

Increased transglutaminase activity was associated with IL-6 release in cultured human gingival fibroblasts exposed to dental cast alloys

Summary. Molecular mechanisms underlying gingival and periodontal inflammation caused by dental alloys are still poorly understood. Recently, it has been demonstrated that tissue transglutaminase can be involved in inflammatory cell response. The aim of this study was to evaluate effects of exposure to orthodontic materials on transglutaminase in cultured human gingival fibroblasts. The incubation with Ni–Ti heat-activated (T3) or Ni–Ti super-elastic (T4), and with Ni–Cr–Co (T2) alloys produced respectively 2.5-fold and 8-fold increases in IL-6 release compared with control cultures. Transglutaminase activity was significantly increased in cells exposed to T3 and T4 alloys (about 170% of control; p < 0.05), where it was mainly localized close to inner part of cell membrane. The exposure to T3 and T4 specimens significantly up-regulated also tTG expression compared with control cultures. These data first show an association between IL-6 release and tissue transglutaminase increases, suggesting that TGase-mediated reactions may play a major role in periodontal inflammation.     

Using cellular automata images and pseudo amino acid composition to predict protein subcellular location

Summary. The avalanche of newly found protein sequences in the post-genomic era has motivated and challenged us to develop an automated method that can rapidly and accurately predict the localization of an uncharacterized protein in cells because the knowledge thus obtained can greatly speed up the process in finding its biological functions. However, it is very difficult to establish such a desired predictor by acquiring the key statistical information buried in a pile of extremely complicated and highly variable sequences. In this paper, based on the concept of the pseudo amino acid composition (Chou, K. C. PROTEINS: Structure, Function, and Genetics, 2001, 43: 246–255), the approach of cellular automata image is introduced to cope with this problem. Many important features, which are originally hidden in the long amino acid sequences, can be clearly displayed through their cellular automata images. One of the remarkable merits by doing so is that many image recognition tools can be straightforwardly applied to the target aimed here. High success rates were observed through the self-consistency, jackknife, and independent dataset tests, respectively.     

Teratogenicity of 3-hydroxynorvaline in chicken and mouse embryos

Summary. 3-Hydroxynorvaline (HNV; 2-amino-3-hydroxypentanoic acid), a microbial L-threonine analogue, is toxic to mammalian cells and displays antiviral properties. In view of this, we investigated the toxicity and/or potential teratogenicity of HNV in developing chicken and mouse embryos. HNV was administered to chicken embryos (in ovo; dose 75–300 μmole/egg; 48 h post-incubation) and pregnant Hanover NMRI mice (per os; total dose 900–1800 mg/kg body mass; gestation days 7–9). Control animals received sterile saline solutions. Harvested embryos (chicken embryos, 10 days post-incubation; mouse embryos; gestation day 18) were fixed in glutaraldehyde and stereomicroscopically inspected for signs of dysmorphogenesis. Body mass, body and toe length and mortality of chicken embryos, and the body mass and mortality of mouse embryos were recorded. HNV exposure significantly increased the incidence of embryotoxic (growth retardation, toxic mortality) and congenital defects in both chicken and mouse embryos. All the observed effects were dose-dependent. In conclusion, HNV is an embryotoxic and teratogenic compound, which caused significant developmental delay and congenital defects in developing chicken and mouse embryos.     

Studies of aminochrome toxicity in a mouse derived neuronal cell line: is this toxicity mediated via glutamate transmission?

Summary. Aminochrome was found to be toxic in a mouse-derived neuronal cell line (CNh). The effect was concentration dependent (10–150 μM). The issue whether aminochrome toxicity involves glutamate transmission was studied with several glutamate receptors antagonists. Incubation of the cells with aminochrome (150 μM) in the presence of 100 μM of the AMPA an-tagonist, NBQX resulted in an increase of cell survival, from 52 to 73%. However, this protective effect did not seem to be related to activation of ionotropic glutamate receptors since incubation of CNh cells with 200 μM of glutamate resulted in only 10% decrease of cell survival. However, NBQX was found to inhibit in vitro the autoxidation process. One hundred μM AP-5 did not have any effect on aminochrome toxicity. The toxic effect of aminochrome on CNh cells seems to be dependent of extracellular activation since addition of dicoumarol, a specific inhibitor of DT-diaphorase, did not affect that toxicity, which can be explained perhaps by a lack of a transport system for aminochrome into the CNh cells. Received July 28, 1999, Accepted December 6, 1999     

The usefulness of radiotracers to make the body biochemically transparent

Summary. Radioactive isotopes are uniquely applicable to observe reactions or circuits of reactions at the molecular level without disturbing the system being studied. The advent of molecular imaging modalities, particularly positron emission tomography (PET), is a major breakthrough for the visualisation and quantitative assessment of cellular and molecular processes occurring in living tissues. The recent development of animal PET scanners that offers 2-mm resolution and is tailored to laboratory rodent models, has made a further great impact on in vivo biochemistry. With these live-imaging modalities at hand, radiotracer-based technologies allow to look directly at biochemical distribution and interaction processes. Tremendous progress made in radiotracer chemistry, primarily in carbon-11 and fluorine-18 radiochemistry, and in the design of imaging devices strengthens the usefulness of radiotracers in nuclear medicine and drug research and development and opens exciting opportunities for new applications, e.g., in food science.     

Influence of nitric oxide synthase activity on amino acid concentration in the quinolinate lesioned rat striatum: A microdialysis and histochemical study

Summary. The influence of nitric oxide synthase (NOS) activity on the KCl-evoked amino acid concentrations was investigated by in vivo microdialysis in the striatum in a rat model of excitotoxic lesion. Basal microdialysate levels of amino acids decreased during the quinolinic acid-induced neurodegeneration process, except for glutamine that increased initially and returned to control values 30 days after quinolinic acid exposure. KCl-evoked increase of extracellular amino acid concentration was reduced due to NOS activity in the striatum of both controls and lesioned animals, except for 120 days after quinolinic acid injection. These changes of amino acid concentrations in microdialysates correlated with the known biochemistry of the consecutive domineered cell types during the lesion process as revealed by histochemistry for NOS, NADPH-diaphorase, GFAP and isolectin B4. The present data provide direct evidence that NOS activity can modulate extracellular amino acid concentrations in the striatum not only under physiological conditions, but also during a pharmacologically induced lesion process and, thus, suggests that nitric oxide affects neurodegeneration via this pathway. Received October 20, 1999; Accepted February 25, 2000     

Growth, ageing and death of a photoautotrophic plant cell culture

 Batch cultures of photoautotrophic cell suspensions of Chenopodiumrubrum L., growing in an inorganic medium on CO₂ under a daily balanced light–dark regime of 16 : 8 h could be maintained for approximately 100 d without subcultivation. The long-lived cultures showed an initial cell division phase of 4 weeks, followed by a stationary phase of another 4 weeks, after which ageing and progressive cell death reduced the number of living cells and the cultures usually expired after another 3–4 weeks. These developmental phases of the cell culture were characterised with respect to photosynthetic performance, dark respiration, content of phytohormones and capacity of cell division. Cell division of the majority of the cells finished in the G1- or G0-phase of the cell cycle, caused by a pronounced decline in the endogenous levels of auxin and cytokinins. Supply of these growth factors to resting cells resulted in resumption of cytokinesis, at least by some of the cells. However, responsiveness to the phytohomones declined during the stationary phase, and subcultivation was no longer possible beyond day 60 when the phases of ageing and death commenced. Ageing was characterised by a further decline in the photosynthetic capacity of the cells, by a climacteric enhancement of dark respiration, but also by a slight increase in the level of IAA and cytokinins concomitant with a decrease in ethylene. Similarities and differences between the development of batch-cultured photoautotrophic cells of C. rubrum and that of a leaf are discussed with respect to using the cell culture as a model for a leaf. Received: 30 April 1999 / Accepted: 21 August 1999     

Transgenic Nicotiana tabacum and Arabidopsis thaliana plants overexpressing allene oxide synthase

 Allene oxide synthase (AOS), encoded by a single gene in Arabidopsis thaliana (L.) Heynh., catalyzes the first step specific to the octadecanoid pathway. Enzyme activity is very low in control plants, but is upregulated by wounding, octadecanoids, ethylene, salicylate and coronatine (D. Laudert and E.W. Weiler, 1998, Plant J 15: 675–684). In order to study the consequences of constitutive expression of AOS on the level of jasmonates, a complete cDNA encoding the enzyme from A. thaliana was constitutively expressed in both  A. thaliana and tobacco (Nicotiana tabacum L.). Overexpression of AOS did not alter the basal level of jasmonic acid; thus, output of the jasmonate pathway in the unchallenged plant appears to be strictly limited by substrate availability. In wounded plants overexpressing AOS, peak jasmonate levels were 2- to 3-fold higher compared to untransformed plants. More importantly, the transgenic plants reached the maximum jasmonate levels significantly earlier than wounded untransformed control plants. These findings suggest that overexpression of AOS might be a way of controlling defense dynamics in higher plants. Received: 10 February 2000 / Accepted: 11 March 2000     

Late steps of egg cell differentiation are accelerated by pollination in Zea mays L.

 Egg cells were analysed cytologically during the female receptivity period in maize (Zea mays L., line A 188). Three classes of egg cell were distinguished: type A – small, non-vacuolated cells with a central nucleus; type B – larger cells with small vacuoles surrounding the perinuclear cytoplasm located in the middle of the cell; type C – big cells with a large apical vacuole and the mid-basal perinuclear cytoplasm. The less-dense cytoplasm of the vacuolated egg cells usually contained numerous cup- or bell-shaped mitochondria. The three egg types appear to correspond to three late stages of egg cell differentiation. The frequencies of each of the three egg types were monitored in developing maize ears before and after pollination. In young ears, with the silks just extending out of the husks, small A-type cells were found in about 86% of ovules. Their frequency decreased to about 58% at the optimum silk length, remained unchanged in non-pollinated ears, and fell to 16% at the end of the female receptivity period. However, after pollination and before fertilisation the frequency of these cells decreased to about 33%, and the larger vacuolated egg cells (types B and C) prevailed. At various stages of the receptivity period, pollination accelerated changes in the egg population, increasing the number of ovules bearing larger, vacuolated egg cells. Experiments with silk removal demonstrated that putative pollination signals act immediately after pollen deposition and are not species-specific. Received: 5 February 1999 / Accepted: 28 August 1999     

Characterisation of the thiol–disulphide chemistry of desmopressin by LC, μ-LC, LC-ESI-MS and Maldi-Tof

Summary. To date, the majority of therapeutic peptides and proteins have to be administered via parenteral routes, which are painful and inconvenient. In order to gain sufficient high blood concentrations after oral application, various barriers in the gastrointestinal tract have to be overcome. Apart from a poor membrane uptake and intense enzymatic degradation, this study will demonstrate that thiol–disulphide reactions are an underestimated essential part of the presystemic metabolism. Glutathione, integrative part of the antioxidant defence system in the gastrointestinal tract, may play an important role in the inactivation of orally given peptides and proteins. In order to verify this hypothesis, desmopressin which bears a single disulphide bond was used as model peptide drug. Desmopressin was incubated with GSH in various concentrations, and the extent of thiol/disulphide exchange reactions between the peptide drug and GSH was investigated in dependence on pH and ratio of reactants determined as a function of time via HPLC, LC-MS and Maldi-Tof-MS analyses. Results showed that desmopressin is degraded by 1% reduced glutathione at pH 4 and pH 5.5. In presence of 0.01%, 0.1% and 1% of reduced glutathione 6.1%, 19.4% and 52.1% of desmopressin, respectively, were degraded. The masses of the conjugates after deconvolution measured by liquid chromatography and electrospray ionisation mass spectrometric detection were m/z 1069.67, m/z 1376.50, m/z 1683.40 and m/z 2138. These molecular masses, confirmed by Maldi-Tof-MS analysis, correspond with the masses of conjugates expected in theory. Under defined conditions, these results reveal that thiol–disulphide exchange reactions have a considerable impact on the alteration of peptide drugs and proteins.     

A prokaryotic sucrose synthase gene (susA) isolated from a filamentous nitrogen-fixing cyanobacterium encodes a protein similar to those of plants

Sucrose synthase (SS), a key enzyme in plant carbohydrate metabolism, has recently been isolated from Anabaena sp. strain PCC 7119, and biochemically characterized; two forms (SS-I and SS-II) were detected (Porchia et al. 1999, Planta 210: 34–40). The present study describes the first isolation and characterization of a prokaryotic SS gene, susA, encoding SS-II from that strain of Anabaena. A 7 kbp DNA fragment containing an open reading frame (EMBL accession number AJ010639) with about 30–40% amino acid identity with plant SSs was isolated from an Anabaena subgenomic library. The putative SS gene was demonstrated to encode an SS protein by expression in Escherichia coli. The biochemical properties of the recombinant enzyme were identical to those of the enzyme purified from the cyanobacterial cells. The deduced amino acid sequence of the Anabaena SS diverged from every plant SS reported. The occurrence of SS in cyanobacteria of different taxonomic groups was investigated. The enzyme occurs in several filamentous nitrogen-fixing cyanobacteria but not in two species of unicellular, non-diazotrophic cyanobacteria. Received: 5 January 2000 / Accepted: 7 March 2000