Preface to Below Ground Processes

The Focus Section in this issue of the Journal of ExperimentalBotany (JXB) contains four invited papers from a session heldat the Society for Experimental Biology (SEB) Annual Meetingin Barcelona, Spain, in July 2005 addressing aspects     

Preface to Nitric Oxide Signalling: Plant Growth and Development

Interest in nitric oxide (NO) as an endogenous and potent regulatorof plant growth and development has grown exponentially in thelast few years. The Focus Section in this issue of Journal ofExperimental Botany (JXB) contains six papers based on invitedtalks from a session held at the Society for Experimental Biology(SEB) Annual Meeting in Barcelona, Spain, in     

Digalactosylceramide is the receptor for staphylococcal enterotoxin-B in human kidney proximal tubular cells

We have characterized a glycosphingolipid (GSL) receptor forStaphylococcus enterotoxin-B (SEB) in cultured human kidneyproximal tubular (PT) cells. Solid-phase binding of [¹²⁵I]SEBto the GSL receptor was concentration dependent and was notdisplaceable by two structurally related toxins, such as staphylococcalenterotoxin-A and toxic shock syndrome toxin-1. Rat kidney cellsdid not bind [¹²⁵I]SEB. However, when the rat kidney cells werepre-incubated with digalactosylceramide, there was a concentration-dependentbinding of [¹²⁵I]SEB. Trimethylsilyl derivatization of methylglycosides, followed by gas-liquid chromatography-mass spectrometry(GC-MS), revealed that galactose was the major sugar componentof this putative receptor GSL. The sphingosines present in thisGSL were d18:2, d22:2 and d23:0; the fatty acids present werepalmitate, oleate and stearate. Permethvlation of alditol acetatesand GC-MS revealed two predominant sugars, namely 2, 3, 4 and6 tetramethylgalactital and 2, 3 and 6 trimethylgalactital.The GSL receptor for SEB was sensitive to a-galactosidase, andresistant to (3-galactosidase and fi-glucosidase. Taken together,our studies reveal that the tentative structure of the receptorfor SEB in human kidney PT cells is CerGal     

Human growth hormone response to repeated bouts of aerobic exercise

Kanaley, J. A., J. Y. Weltman, J. D. Veldhuis, A. D. Rogol,M. L. Hartman, and A. Weltman. Human growth hormone response torepeated bouts of aerobic exercise. J. Appl.Physiol. 83(5): 1756-1761, 1997.We examinedwhether repeated bouts of exercise could override growth hormone (GH)auto-negative feedback. Seven moderately trained men were studied onthree occasions: a control day (C), a sequential exercise day (SEB; at1000, 1130, and 1300), and a delayed exercise day (DEB; at 1000, 1400, and 1800). The duration of each exercise bout was 30 min at 70%maximal O₂ consumption (O_{2 max}) on a cycleergometer. Standard meals were provided at 0600 and 2200. GH wasmeasured every 5-10 min for 24 h (0800-0800). Daytime(0800-2200) integrated GH concentrations were ~150-160% greater during SEB and DEB than during C: 1,282 ± 345, 3,192 ± 669, and 3,389 ± 991 min · µg · l¹for C, SEB, and DEB, respectively [SEB > C(P < 0.06), DEB > C(P < 0.03)]. There were nodifferences in GH release during sleep (2300-0700). Deconvolutionanalysis revealed that the increase in 14-h integrated GH concentrationon DEB was accounted for by an increase in the mass of GH secreted perpulse (per liter of distribution volume,l_v): 7.0 ± 2.9 and 15.9 ± 2.6 µg/l_v for C and DEB,respectively (P < 0.01). Comparisonof 1.5-h integrated GH concentrations on the SEB and DEB days (30 minexercise + 60 min recovery) revealed that, with each subsequentexercise bout, GH release apparently increased progressively, with aslightly greater increase on the DEB day [SEB vs. DEB: 497 ± 162 vs. 407 ± 166 (bout 1), 566 ± 152 vs. 854 ± 184 (bout2), and 633 ± 149 vs. 1,030 ± 352 min · µg · l¹(bout 3),P < 0.05]. We conclude thatthe GH response to acute aerobic exercise is augmented with repeatedbouts of exercise.

     

Prolonged exercise increases peripheral plasma ACTH, CRH, and AVP in male athletes

We wished to determine whether the increased ACTH duringprolonged exercise was associated with changes in peripheralcorticotropin-releasing hormone (CRH) and/or argininevasopressin (AVP). Six male triathletes were studied during exercise: 1 h at 70% maximal oxygen consumption, followed by progressivelyincreasing work rates until exhaustion. Data obtained during theexercise session were compared with a nonexercise control session.Venous blood was sampled over a 2-h period for cortisol, ACTH, CRH,AVP, renin, glucose, and plasma osmolality. There were significantincreases by ANOVA on log-transformed data in plasma cortisol(P = 0.002), ACTH(P < 0.001), CRH(P < 0.001), and AVP(P < 0.03) during exercise comparedwith the control day. A variable increase in AVP was observed after the period of high-intensity exercise. Plasma osmolality rose with exercise(P < 0.001) and was related toplasma AVP during submaximal exercise(P < 0.03) but not with theinclusion of data that followed the high-intensity exercise. Thisindicated an additional stimulus to the secretion of AVP. The mechanismby which ACTH secretion occurs during exercise involves both CRH andAVP. We hypothesize that high-intensity exercise favors AVP release andthat prolonged duration favors CRH release.

     

Morphological Adaptations of the Ear in the Rodent Family Heteromyidae

Middle and inner ear structure and auditory sensitivity havebeen studied in all five genera of the rodent family Heteromyidae.In the most xericc genera (Dipodomys and Microdipodops) themiddle ears are greatly inflated the tympano-ossicular systemvery efficient the organ of Corti extremely modified and low-frequencysensitivity extremely acute. In the most mesic genera (Heteromysand Liomys) the middle and inner ears show few modificationsand the low frequency sensitivity is rather poor. Perognathusis intermediate in habitat structure, and low frequency sensitivity.Experimental data demonstrate that the low frequency sensitivityin Dipodomys is adaptive in predator avoidance.     

Thermodynamic and structural analysis of interactions between peptide ligands and SEB

Staphylococcal enterotoxin B (SEB) is an exotoxin produced by Staphylococcus aureus and commonly associated with food poisoning. In this study, SEB‐binding peptides were identified by screening a phage displayed peptide library. The binding of peptides to SEB was tested with isothermal titration calorimetry (ITC) and of the five selected peptides, three showed affinity to SEB, with one measured to have the highest affinity constant (10⁵ M^?1). ITC revealed that the interaction of peptide ligands with SEB was driven entropically and the binding was dominated by hydrophobic interactions. Circular dichroism (CD) measurements and molecular dynamics (MD) simulations, together, give a structural insight into the interaction of peptides with SEB. While SEB binding peptides showed random coil structure before binding, after complex formation they had more ordered structures. The peptide with highest affinity to SEB showed stable conformation during MD simulation. Taken together, our approach about thermodynamic and structural characterization of peptide ligands can be used to develop aptamers, with high affinity and selectivity, for biosensor applications. Copyright © 2009 John Wiley & Sons, Ltd.     

ERRATA

E.A Gwozdz,J.D.Bewley and E.B.Tucker(1974).Studies on proteinsynthesis in Tortula ruralis,Journal of Experimental Botany,25, 599–608 P.S. Nobel (1975). Effective thickness and resistance of theair boundary layer adjacent to spherical plant parts.Journalof Experimental Botany, 26 120–130     

Effects of four different single exercise sessions on lipids, lipoproteins, and lipoprotein lipase

The purpose ofthis study was to determine the threshold of exercise energyexpenditure necessary to change blood lipid and lipoproteinconcentrations and lipoprotein lipase activity (LPLA) in healthy,trained men. On different days, 11 men (age, 26.7 ± 6.1 yr; bodyfat, 11.0 ± 1.5%) completed four separate, randomly assigned,submaximal treadmill sessions at 70% maximalO₂ consumption. During eachsession 800, 1,100, 1,300, or 1,500 kcal were expended. Compared withimmediately before exercise, high-density lipoprotein cholesterol(HDL-C) concentration was significantly elevated 24 h after exercise(P < 0.05) in the 1,100-, 1,300-, and 1,500-kcal sessions. HDL-C concentration was also elevated(P < 0.05) immediately after and 48 h after exercise in the 1,500-kcal session. Compared with values 24 hbefore exercise, LPLA wassignificantly greater (P < 0.05) 24 h after exercise in the 1,100-, 1,300-, and 1,500-kcal sessions andremained elevated 48 h after exercise in the 1,500-kcal session. Thesedata indicate that, in healthy, trained men, 1,100 kcal of energyexpenditure are necessary to elicit increased HDL-C concentrations.These HDL-C changes coincided with increased LPLA.

     

A comparison between methods used to control nutrient supply

Experimental methods to supply nutrients to culture solutionsin order quantitatively to control plant nutrition are compared.In experiments with tomato and birch plants, for which the dataare available in databases (Ingestad et al., 1994a, b), thenutrients were supplied at constant relative addition rates(R_A over sufficiently long periods of time to achieve acclimatedplants and reliable measurements of plant responses. The plantswere maintained under steady-state conditions, i.e. the internalnutrient concentrations (c₁) remained constant, as a resultof a numerical equality between the relative uptake rate (R_U)and the relative growth rate (R_G). These results are comparedto experiments with pea plants (Macduff et al., 1993). In oneseries (a), R_A was applied, but without strict control of internalsteady-state, and in the other series (b), the external concentration(c_e) was maintained constant. With limiting nitrogen, in bothseries, there was a substantial deviation from equality betweenR_U and R_G. In (a), c_I changed during the experimental periodand the purpose of the R_A approach was lost. In (b), a constantc_e had little effect on nitrogen uptake and plant growth. Atthe three highest concentrations, steady-states were obtainedat non-limiting uptake rates. At the lowest concentration, theuptake rate of nitrogen was about the same, but there was adecrease of R_a, which apparently was not caused by reduced uptake.Clear-cut relationships can not therefore be established betweentreatment variables and plant responses and the conclusionsreached by Macduff et al. (1993) have little support in theirexperimental results. This indicates an urgent need to updateboth theories and experimental methods together: in particular,it is important to identify the system under investigation andto distinguish between control of the medium and control ofthe plant. Key words: Experimental control, external nutrient concentration, non-limiting and limiting nutrient supply, relative addition rate, relative uptake rate, relative growth rate, steady-state     

Society for Molecular Biology and Evolution Council and Business Meetings, 2002

Council Meeting, 2002 Call to order.—The SMBE Council met during two sessionsat the Sorrento Hilton, Sorrento, Italy. President Michael Cleggcalled the first session to order at 1:37 p.m. on June 13, 2002and the second at 1:15 p.m. on June 14, 2002. In attendanceat the first session were Councilor Montserrat Aguadé,President Michael Clegg, Editor Simon Easteal, Treasurer DickHudson, and Secretary Marcy Uyenoyama; these Council memberswere joined at the second session by President-Elect NaoyukiTakahata. S. Blair Hedges, organizer of the 2004 annual meetings,made a     

The Influence of Photoperiod on the Timing of Reproductive Cycles in Gammarus species (Crustacea, Amphipoda)

SYNOPSIS. Gammarus species time the release of their young byusing ovarian diapause and the duration of embryonic development.During diapause vitellogenesis is arrested and oostegite setaeare lost. The onset of diapause is influenced by photoperiodunder experimental conditions. Two Gammarus species were studied.Gammarus lawrencianus is typical of the majority of Gammarusspecies that produce sequential broods through the summer andhave a diapause in the autumn. Gammarus setosus is typical ofthose which have an obligatory diapause lasting most of theyear that follows the annual autumn brood. Experimental shortday photoperiods (4L to 12L) induce vitellogenesis in Gammarussetosus, and have the opposite effect on Gammarus lawrencianus.Long day photoperiods promote vitellogenesis in Gammarus lawrencianusand prolong the duration of diapause in Gammarus setosus. Itis concluded that these two Gammarus species have their ownendogenous rhythms and that the role of photoperiod is to timethe reproductive cycle. Short days near the time of the fallequinox ensure that this timing is synchronized over a rangeof latitudes. The effect of photoperiod is modulated by theinfluence of temperature on embryonic development over the broadrange of geographic latitude inhabited by the species. Shortphotoperiods inhibit but do not prevent sexual maturation ofthe young. Short days also result in a slower average growthrate and greater size at maturity.     

Isolation of a new ssDNA aptamer against staphylococcal enterotoxin B based on CNBr‐activated sepharose‐4B affinity chromatography

Staphylococcus aureus are potent human pathogens possessing arsenal of virulence factors. Staphylococcal food poisoning (SFP) and respiratory infections mediated by staphylococcal enterotoxin B (SEB) are common clinical manifestations. Many diagnostic techniques are based on serological detection and quantification of SEB in different food and clinical samples. Aptamers are known as new therapeutic and detection tools which are available in different ssDNA, dsDNA and protein structures. In this study, we used a new set of ssDNA aptamers against SEB. The methods used included preparation of a dsDNA library using standard SEB protein as the target analyte, affinity chromatography matrix in microfuge tubes, SELEX procedures to isolate specific ssDNA‐aptamer as an affinity ligand, aptamer purification using ethanol precipitation method, affinity binding assay using ELISA, aptamer cloning and specificity test. Among 12 readable sequences, three of them were selected as the most appropriate aptamer because of their affinity and specificity to SEB. This study presents a new set of ssDNA aptamer with favorable selectivity to SEB through 12 rounds of SELEX. Selected aptamers were used to detect SEB in infected serum samples. Results showed that SEB c1 aptamer (2 µg SEB/100 nM aptamer) had favorable specificity to SEB (k_d = 2.3 × 10^?11). In conclusion, aptamers can be considered as useful tools for detecting and evaluating SEB. The results showed that affinity chromatography was an affordable assay with acceptable accuracy to isolate sensitive and selective novel aptamers. Copyright © 2016 John Wiley & Sons, Ltd.     

Male fruit flies learn to avoid interspecific courtship

Experimental data suggest, and theoretical models typicallyassume, that males of many fruit flies (Drosophila spp) areat least partially indiscriminate while searching for mates,and that it is mostly the females who exert selective mate choice,which can lead to incipient speciation. Evidence on learningby male D. melanogaster in the context of courtship, however,raises the possibility that the initially indiscriminate malesbecome more selective with experience. I tested this possibilityby comparing the courtship behavior of male D. melanogasterexperienced at courting females of the closely related species,D. simulans, and inexperienced males. I found that comparedwith the inexperienced males, the males experienced with courtingD. simulans females showed significantly lower courtship towardfemale D. simulans. Both male treatments, however, showed virtuallyidentical courtship durations with female D. melanogaster. Theseresults indicate that male fruit flies adaptively refine theircourtship behavior with experience and suggest that the malescontribute more to assortative mating and incipient speciationthan is commonly assumed.     

Influences of local feedbacks on land–air exchanges of energy and carbon

Land–air exchanges of energy and matter are modulated by several feedback processes at both small and large space and time scales, with implications for the linked carbon, water and energy cycles. This paper studies the influences of four local feedbacks, occurring at single-patch spatial scales and subdiurnal temporal scales, on the surface energy balance (SEB) and land–air carbon fluxes. The feedbacks are: (i) radiative feedback, the modulation of available energy through the effect of surface temperature, T_s, on outgoing longwave radiation; (ii) physiological feedback, the interaction between vegetation physiology and the SEB through T_s; (iii) aerodynamic feedback, the modulation of turbulent heat and moisture transfer by atmospheric stability; and (iv) Convective Boundary Layer (CBL) feedback, the coupling between the daytime evolution of the SEB and CBL through saturation deficit. It is found that radiative feedback is significant only over very smooth surfaces. Physiological feedback is positive with respect to T_s at moderate to high temperatures, pushing stomata towards complete closure and the SEB towards very low evaporation rates. The SEB is quite sensitive to whether or not such closure occurs. Aerodynamic feedback, on the other hand, is negative with respect to T_s at these temperatures, reducing T_s and attenuating the tendency for heat-induced stomatal closure. CBL feedback alone does not dampen the sensitivity of the SEB to physiological feedback and stomatal closure. However, when aerodynamic feedback is included, this sensitivity is greatly reduced.     

Immunoquantitative Real-Time PCR for Detection and Quantification of Staphylococcus aureus Enterotoxin B in Foods

A real-time immunoquantitative PCR (iqPCR) method for detection of Staphylococcus aureus enterotoxin B (SEB) was developed and evaluated using both pure cultures and foods. The assay consisted of immunocapture of SEB and real-time PCR amplification of the DNA probe linked to the detection antibody. iqPCR was compared to an in-house enzyme-linked immunosorbent assay (ELISA) using the same couple of capture-detection antibodies and to commercial kits for detection of S. aureus enterotoxins (SE). The iqPCR was approximately 1,000 times more sensitive (<10 pg ml⁻¹) than the in-house ELISA and had a dynamic range of approximately 10 pg ml⁻¹ to approximately 30,000 pg ml⁻¹. iqPCR was not inhibited by any of the foods tested and was able to detect SEB present in these foods. No cross-reactivity with SE other than SEB was observed. Application of iqPCR for detection of SEB in cultures of S. aureus revealed the onset of SEB production after 4 h of incubation at 22, 37, and 42°C, which was in the first half of the exponential growth phase. The total amounts of SEB produced by the two strains tested were larger at 42°C than at 37°C and were strain dependent.     

Immunosuppression induced by staphylococcal enterotoxin B

Staphylococcal enterotoxin B (SEB) is a potent mitogen for both human and murine T lymphocytes. We report here studies which demonstrate that a suppressor cell population, capable of suppressing the primary immune response of normal syngeneic mouse splenocytes to heterologous sheep erythrocytes (SRBC), is activated by SEB. Enterotoxin concentrations ranging from 0.05 to 5.0 Mg ml^?1 are capable of activating this suppressor cell population, and significant suppression can be detected with relatively small numbers of SEB-primed spleen cells (SEB-PSC) in culture. Elimination of macrophages before or after priming splenocytes with SEB does not reduce the suppression of plaque-forming cell (PFC) responses when SEB-PSC are added to normal cells in Mishell-Dutton cultures. Treatment of cells with anti-Thy-1 serum plus complement, after priming with SEB, effectively eliminates the activity of the suppressor cell population. Enrichment for T cells before priming with SEB results in greater suppression of PFC responses than do SEB-PSC generated in cultures of nonfractionated splenocytes. Activation of suppressor cells with SEB in vitro appears to occur through the induction of the T-cell subpopulation expressing the Lyt-1^?,2⁺,3⁺ cell surface phenotype, since selective depletion of this T-cell subpopulation with monoclonal rat anti-mouse Lyt-2 antisera after priming cells with SEB virtually eliminates the suppressor activity.     

THE INFLUENCE OF FOOD DEPRIVATION ON THE LOCOMOTOR ACTIVITY OF SLUGS

Experimental animals used in studies of feeding behaviour areusually starved prior to observation, although little is knownof the behavioural effects of such pre-experimental treatment.This study investigated the effect of food deprivation on thelocomotor activity of two species of slugs, Deroceras reticulatumand Milax budapestensis. Locomotor activity was measured bythe quantitative assessment of mucus trails. The more surfaceactiveD. reticulatum showed a marked increase in its locomotoractivity when deprived of food, whereas the locomotor activityof M. budapestensis decreased. The implications of the resultsare discussed in relation to the ‘life-styles’ ofthe two species and the possible implications for the controlof slugs in the potato crop. ^*Present address: 59 Valley Park Drive, Clanfield, Hants. PO80PL. (Received 24 May 1986;     

Exhaustive removal of N-glycans from ascorbate oxidase: effect on the enzymatic activity and immunoreactivity

Purified ascorbate oxidase from Cucurbita pepo medullosa hasbeen subjected to enzymatic deglycosylation using peptide N-glycosidaseF. Experimental conditions were chosen to obtain efficientlydeglycosylated and active ascorbate oxidase: in particular,three different detergent solutions were added separately tothe incubation mixtures prior to the peptide N-glycosidase F.The detergent solution made of 0.1% (w/v) sodium dodecyl sulphate+ 0.5% (v/v) Nonidet P-40 proved to be the only one effectivefor our purpose. Our results indicate that: (i) the presenceof detergents did not affect the enzymatic activity; (ii) fullydeglycosylated enzyme retained its activity compared with thenative form. Moreover, anti-native ascorbate oxidase antibodiesscarcely recognized deglycosylated protein. ascorbate oxidase blot deglycosylation     

T cell activation and retargeting using staphylococcal enterotoxin B and bispecific antibody: An effective in vivo antitumor strategy

 The aim of this work was to test for cure and immunity in a micrometastatic tumor model using in vivo T cell activation with staphylococcal enterotoxin B (SEB) and retargeting with antitumor×anti-CD3 F(ab′)₂ bispecific antibodies (bsAb). All studies were performed in C3H/HeN mice using syngeneic tumor cell lines. For survival studies, mice were injected intravenously on day 0 with CL62 (a p97-transfected clone of the K1735 murine melanoma tumor). Day-3 treatments included saline (control), SEB (50 γg intraperitoneal) with or without bsAb (5 μg i.v.). Cured mice, surviving beyond 60 days, were rechallenged with subcutaneous CL62, K1735, or a nonmelanoma control, AG104. SEB activation studies were performed with pulmonary tumor-infiltrating lymphocytes isolated from 10-day established CL62 tumors. Maximal tumor-infiltrating lymphocyte cytotoxicity was demonstrated 24 h following SEB injection, therefore bsAb treatments were administered 24 h after SEB. When survival was examined at 60 days, there were significantly more survivors in the group receiving SEB plus bsAb (70%) compared to the group receiving SEB alone (30%), and the controls (0%) (P=0.02 and P<0.01, respectively). Mice cured of CL62 using SEB alone or with bsAb demonstrated equal immunity to CL62, however, mice treated with SEB plus bsAb were more often immune to the p97^– parental cell line, K1735(P=0.001). Ag104 consistently grew in all mice. Results of these studies demonstrate that SEB plus bsAb can be effective, not only in curing tumors but also in providing protective immunity against targeted and nontargeted tumor antigens. Accepted: 14 October 1997