A soybean growth model based on compensatory growth following defoliation

On the basis of an artificial defoliation experiment, a new growth model of soybean was formulated through a modification of Rudd's (1980) model with regard to his equations for dry matter allocation. Compensatory growth for leaf damage was modelled by a single process in which the dry matter allocation changes dynamically according to the severity of leaf damage. The sums of squared differences between simulations and experimental soybean yields were much smaller in our modified model than in Rudd's original model. The modified model gave a better simulation of yield loss due to defoliation that varied in time and intensity. The relationship between various times and intensities of defoliation and yield loss was shown, which is essential for establishing the dynamic economic injury level in IPM.     

Phosphorylation of smooth muscle heavy meromyosin by calcium-activated, phospholipid-dependent protein kinase. The effect on actin-activated MgATPase activity

Smooth muscle heavy meromyosin (HMM) can serve as a substrate for the Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C) as well as for the Ca2+/calmodulin-dependent kinase, myosin light chain kinase. When turkey gizzard HMM is incubated with protein kinase C, 1.7-2.2 mol of phosphate are incorporated per mol of HMM, all of it into the 20,000-Da light chain of HMM. Two-dimensional peptide mapping following tryptic hydrolysis revealed that protein kinase C phosphorylated a different site on the 20,000-Da HMM light chain than did myosin light chain kinase. Moreover, sequential phosphorylation of HMM by myosin light chain kinase and protein kinase C resulted in the incorporation of 4 mol of phosphate/mol of HMM, i.e. 2 mol of phosphate into each 20,000-Da light chain. When unphosphorylated HMM was phosphorylated by myosin light chain kinase, its actin-activated MgATPase activity increased from 4 nmol to 156 nmol of phosphate released/mg of HMM/min. Subsequent phosphorylation of this phosphorylated HMM by protein kinase C decreased the actin-activated MgATPase activity of HMM to 75 nmol of phosphate released/mg of HMM/min.     

Serologic dissection of HLA-D specificities by the use of monoclonal antibodies

To study the gene products of the HLA complex, we produced two monoclonal antibodies, termed HU-18 and HU-23. They were active in complement-dependent cytotoxicity and detected B-cell alloantigens encoded by a locus (or loci) linked to HLA. When three types of HLA-DR4 homozygous B-cell lines with different HLA-D specificities were tested for reactivity with HU-18 and HU-23, they displayed distinct reaction patterns depending on the HLA-D specificities they possessed: EBV-Wa (HLA-DYT homozygous), negative for both HU-18 and HU-23; KT2 and KOB (HLA-DKT2 homozygous), positive only for HU-18; and ER (HLA-Dw4 homozygous), positive for both. These differential reaction patterns were further confirmed by testing against a panel of 17 HLA-DR4-positive peripheral blood lymphocytes with known HLA-D specificities. Thus, these monoclonal antibodies allow us to identify HLA-DYT, HLA-DKT2, and HLA-Dw4 solely by serologic methods. This is the first clearcut serologic identification of these three HLA-DR4-associated HLA-D specificities, which have been indistinguishable by conventional serology and identified only by cellular techniques. It is hoped that immunochemical investigations using HU-18 and HU-23 will advance our understanding of the HLA-D region on a molecular level.     

A New Enzymatic Cycling Technique for Glutamate Determination in Brain Microdialysates

A quantitative analysis of glutamate in brain dialysate was made by using an enzymatic cycling technique. This method made it possible to measure the concentration of glutamate in dialysate collected at 30-s intervals. Dialysates were collected from Mongolian gerbil hippocampus before, during, and after two 90-s ischemic insults at an interval of 5 min. An extracellular increase in levels of glutamate was already observed in samples collected during a 30-60 s period after the onset of each ischemia, and the levels of glutamate were maximal at the end of each period of ischemia (approximately a fourfold increase). The increased levels of glutamate rapidly returned almost to preischemic levels by 30 s of recirculation. This method will provide more precise information about temporal changes in the extracellular glutamate concentration in the brain during ischemia.     

Similarity of the outer capsid protein VP4 of the Gottfried strain of porcine rotavirus to that of asymptomatic human rotavirus strains.

Genomic segment 4 of the porcine Gottfried strain (serotype 4) of porcine rotavirus, which encodes the outer capsid protein VP4, was sequences, and its deduced amino acid sequence was analyzed. Amino acid homology of the porcine rotavirus VP4 to the corresponding protein of asymptomatic or symptomatic human rotaviruses representing serotypes 1 to 4 ranged from 87.1 to 88.1% for asymptomatic strains and from 77.5 to 77.8% for symptomatic strains. Amino acid homology of the Gottfried strain to simian rhesus rotavirus, simian SA11 virus, bovine Nebraska calf diarrhea virus, and porcine OSU strains ranged from 71.5 to 74.3%. Antigenic similarities of VP4 epitopes between the Gottfried strain and human rotaviruses were detected by a plaque reduction neutralization test with hyperimmune antisera produced against the Gottfried strain or a Gottfried (10 genes) x human DS-1 rotavirus (VP7 gene) reassortant which exhibited serotype 2 neutralization specificity. In addition, a panel of six anti-VP4 monoclonal antibodies capable of neutralizing human rotaviruses belonging to serotype 1, 3, or 4 was able to neutralize the Gottfried strain. These observations suggest that the VP4 outer capsid protein of the Gottfried rotavirus is more closely related to human rotaviruses than to animal rotaviruses.     

Substance-P-like immunoreactive subepithelial nerve plexuses in the labial mucosa of the mouse

Substance P (SP)-like immunoreactivity was examined in the lower labial mucosa of the mouse by using the whole-mount technique. The density and design of subepithelial nerve plexuses containing SP differed depending on portions of the lower labial mucosa.     

Light Activation of Pyruvate, Orthophosphate Dikinase in Maize Mesophyll Chloroplasts: A Role for Adenylate Energy Charge

Pyruvate, orthophosphate dikinase (EC 2.7.9.1 [EC] ) was activatedin the light and inactivated following a dark treatment in intactmaize mesophyll chloroplasts. Addition of catalase (100–250units/ml) to the assay medium was necessary to obtain good activationand to keep the enzyme in an active state during illumination.Arsenate and carbonyl cyanide m-chlorophenyl-hydrazone, uncouplersof photophosphorylation, inhibited the activation. Pyruvate,which has been proposed to have a critical role in supportingthe light activation of pyruvate, orthophosphate dikinase, actuallyinhibited the activation. The pyruvate level in the chloroplastsuspension decreased when the enzyme was light-activated. Measurementsof adenylates and pyruvate in the chloroplasts indicated thatthe energy state of the chloroplasts was more important forthe light activation than was the level of pyruvate. ¹Present address: Department of Biochemistry, Faculty of Science,Saitama University, 255, Shimo-Okubo, Urawa, 338 Japan ²Present address: National Institute of Agrobiological Resources,Yatabe, Tsukuba, Ibaraki, 305 Japan (Received May 2, 1989; Accepted October 2, 1989)     

The role of 5'-methylthioadenosine on rat calvaria cell differentiation.

The role of 5'-methylthioadenosine (MTA), formed during the process of polyamine biosynthesis, on differentiation of osteoprogenitor cells was assessed by its effects on alkaline phosphatase (ALP) activity, bone nodule formation and osteopontin contents of cultured rat calvaria (RC) cells. These three markers were stimulated by exogenous MTA and were depressed by 5'-difluoromethylthioadenosine (DFMTA), a synthetic inhibitor of MTA phosphorylase, which cleaves MTA to adenine and 5-methylthioribose-1-phosphate. 5-Methylthioribose and 2-keto-4-methylthiobutyrate, metabolites of 5-methylthioribose-1-phosphate, had no effects on ALP activity and bone nodule formation in the presence or absence of DFMTA. On the other hand, adenine enhanced ALP activity, bone nodule formation and osteopontin contents in mineralized nodules and also partially reversed DFMTA-induced inhibition of these three markers. MTA, its metabolites and DFMTA did not affect the growth of RC cells under these culture conditions. These results suggest that adenine formed from MTA is important in the differentiation of RC cells.