Mugineic acid secretion by cultured barley cells derived from anther

Summary Primordial germ cells with a retroviral DNA have been transferred to recipient fowl embryos without this marker. The foreign DNA was subsequently identified in the gonads of these birds. This suggests that primordial germ cells may be a useful route for introducing DNA into transgenic birds.Abbreviations SSC saline sodium citrate - pRAV-1 plasmid of RAV-1, a subgroup of avian leukosis virus     

Molecular cloning of a full-length cDNA for human alpha-N-acetylgalactosaminidase (alpha-galactosidase B)

In the process of molecular cloning of cDNA for proteins associated with a purified human placental sialidase fraction, we discovered one of the proteins with apparent molecular weight of 46 kDa is in reality alpha-N-acetylgalactosaminidase. The full length cDNA, pcD-HS1204, codes for 358 amino acids with the first 17 residues representing a putative signal peptide. The predicted amino acid sequence shows striking homology with human alpha-galactosidase A and yeast alpha-galactosidase. The substrate specificities as well as the behavior of the 46 kDa protein on hydroxylapatite chromatography confirmed that the 46 kDa protein is in reality alpha-N-acetylgalactosaminidase.     

Context Dependent Effect of Landscape on the Occurrence of an Apex Predator across Different Climate Regions

In studies of habitat suitability at landscape scales, transferability of species-landscape associations among sites are likely to be critical because it is often impractical to collect datasets across various regions. However, limiting factors, such as prey availability, are not likely to be constant across scales because of the differences in species pools. This is particularly true for top predators that are often the target for conservation concern. Here we focus on gray-faced buzzards, apex predators of farmland-dominated landscapes in East Asia. We investigated context dependency of “buzzard-landscape relationship”, using nest location datasets from five sites, each differing in landscape composition. Based on the similarities of prey items and landscape compositions across the sites, we determined several alternative ways of grouping the sites, and then examined whether buzzard-landscape relationship change among groups, which was conducted separately for each way of grouping. As a result, the model of study-sites grouping based on similarities in prey items showed the smallest ΔAICc. Because the terms of interaction between group IDs and areas of broad-leaved forests and grasslands were selected, buzzard-landscape relationship showed a context dependency, i.e., these two landscape elements strengthen the relationship in southern region. The difference in prey fauna, which is associated with the difference in climate, might generate regional differences in the buzzard-landscape associations.     

Total Mechanical Unloading Minimizes Metabolic Demand of Left Ventricle and Dramatically Reduces Infarct Size in Myocardial Infarction

BackgroundLeft ventricular assist device (LVAD) mechanically unloads the left ventricle (LV). Theoretical analysis indicates that partial LVAD support (p-LVAD), where LV remains ejecting, reduces LV preload while increases afterload resulting from the elevation of total cardiac output and mean aortic pressure, and consequently does not markedly decrease myocardial oxygen consumption (MVO₂). In contrast, total LVAD support (t-LVAD), where LV no longer ejects, markedly decreases LV preload volume and afterload pressure, thereby strikingly reduces MVO₂. Since an imbalance in oxygen supply and demand is the fundamental pathophysiology of myocardial infarction (MI), we hypothesized that t-LVAD minimizes MVO₂ and reduces infarct size in MI. The purpose of this study was to evaluate the differential impact of the support level of LVAD on MVO₂ and infarct size in a canine model of ischemia-reperfusion.MethodsIn 5 normal mongrel dogs, we examined the impact of LVAD on MVO₂ at 3 support levels: Control (no LVAD support), p-LVAD and t-LVAD. In another 16 dogs, ischemia was induced by occluding major branches of the left anterior descending coronary artery (90 min) followed by reperfusion (300 min). We activated LVAD from the beginning of ischemia until 300 min of reperfusion, and compared the infarct size among 3 different levels of LVAD support.Resultst-LVAD markedly reduced MVO₂ (% reduction against Control: -56 ± 9%, p<0.01) whereas p-LVAD did less (-21 ± 14%, p<0.05). t-LVAD markedly reduced infarct size compared to p-LVAD (infarct area/area at risk: Control; 41.8 ± 6.4, p-LVAD; 29.1 ± 5.6 and t-LVAD; 5.0 ± 3.1%, p<0.01). Changes in creatine kinase-MB paralleled those in infarct size.ConclusionsTotal LVAD support that minimizes metabolic demand maximizes the benefit of LVAD in the treatment of acute myocardial infarction.     

Equivocal Responses of Feeding Parents to Experimental Brood Sizes in a Hawk–Cuckoo Host: Brood Size as a Reference for Parental Provisioning Decisions?

The number of offspring surviving until independence is the fundamental drive in the evolution of parental care. Because of the related costs, parental investment must be balanced with essential resources for parents themselves, among the resources available in the environment under the current parental condition. It is advantageous for parents to adjust their level of investment to the number of offspring; however, there is little evidence that parents employ numerical competence in adjusting their investment level. We investigated how parents respond to experimentally manipulated brood sizes in a passerine species, known as a host of a brood parasitic cuckoo whose chicks presumably deceive their hosts numerically. Parents reduced their provisioning to broods of reduced sizes, whereas parents did not increase provisioning to enlarged broods compared to that in the control condition. These parental responses can be attributed to the response of chicks to the experimental treatments compared to that in the control: chicks lowered begging intensity in the reduced condition, while they did not intensify being in the enlarged condition. Further analyses revealed that eagerness of parents to respond to chick begging intensity differed between the experimental treatments: strong parental response was detected toward begging chicks only in the reduced condition. We propose that the detected equivocality of parental responses might be related to the difference in the number of chicks between the unmanipulated and experimentally manipulated broods, the former reflecting the initial parental decision on the amount of resources to allocate to the brood.     

Diets and body condition of polar cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) in the northern Bering Sea and Chukchi Sea

To understand trophic responses of polar cod Boreogadus saida (a key species in Arctic food webs) to changes in zooplankton and benthic invertebrate communities (prey), we compared its stomach contents and body condition between three regions with different environments: the northern Bering Sea (NB), southern Chukchi Sea (SC), and central Chukchi Sea (CC). Polar cod were sampled using a bottom trawl, and their potential prey species in the environment were sampled using a plankton net and a surface sediment sampler. Polar cod fed mainly on appendicularians in the NB and SC where copepods were the most abundant in the environment, while they fed on copepods, euphausiids, and gammarids in the CC where barnacle larvae were the most abundant species in plankton samples on average. The stomach fullness index of polar cod was higher in the NB and SC than CC, while their body condition index did not differ between these regions. The lower lipid content of appendicularians compared to other prey species is the most plausible explanation for this inconsistency.     

Formate Dehydrogenase, an Enzyme of Anaerobic Metabolism, Is Induced by Iron Deficiency in Barley Roots

To identify the proteins induced by Fe deficiency, we have compared the proteins of Fe-sufficient and Fe-deficient barley (Hordeum vulgare L.) roots by two-dimensional polyacrylamide gel electrophoresis. Peptide sequence analysis of induced proteins revealed that formate dehydrogenase (FDH), adenine phosphoribosyltransferase, and the Ids3 gene product (for Fe deficiency-specific) increased in Fe-deficient roots. FDH enzyme activity was detected in Fe-deficient roots but not in Fe-sufficient roots. A cDNA encoding FDH (Fdh) was cloned and sequenced. Fdh expression was induced by Fe deficiency. Fdh was also expressed under anaerobic stress and its expression was more rapid than that induced by Fe deficiency. Thus, the expression of Fdh observed in Fe-deficient barley roots appeared to be a secondary effect caused by oxygen deficiency in Fe-deficient plants.     

An Immunocytochemical Technique for Analysis of Regulation of Genes Encoding Early Differentiation Marker Antigens in an Oocyte Translation System

Monoclonal antibodies are useful probes for analyzing cells at the molecular level at various developmental stages. Although identification of the genes encoding tissue- and stage-specific antigens could be informative for further molecular analysis, gene cloning is usually a time-consuming step, particularly when a monoclonal antibody is the only probe available. We describe here an immunocytochemical method for preliminary and immediate analysis of the regulation of antigen-coding genes. mRNAs purified from stage 27 and 38 Xenopus tadpoles were fractionated by size and injected into newt oocytes, from which frozen sections were prepared for immunostaining with tissue-specific monoclonal antibodies. Both of the antigens we tested, which are early markers for differentiating epidermal cells of Xenopus tadpoles, were detected in mRNA injected oocytes, but not in control oocytes. Immunostaining for each of the antigens showed that their relative levels in stage 27 and 38 tadpole tissue were reflected in those oocytes injected with mRNA purified from tadpoles of the respective stages. We suggest that this oocyte translation system combined with immuaostaining provides for rapid analysis of changes in levels of antigen coding mRNAs throughout development.     

Effect of 1,25-dihydroxyvitamin D3 on induction of scavenger receptor and differentiation of 12-O-tetradecanoylphorbol-13-acetate-treated THP-1 human monocyte like cells

We investigated the effect of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on the expression of scavenger receptors in human monocytic cell line (THP-1 cells) treated for 24 h with 12-O-tetradecanoylphorbol-13-acetate (TPA) which induces their differentiation into macrophages. The capacity to degrade ¹²⁵I-labeled acetyl low density lipoprotein (LDL) was developed in accordance with macrophage differentiation. The treatment with 10 nM 1,25(OH)₂D₃ for 72 h inhibited the degradation of acetyl LDL by THP-1 macrophages in a dose-dependent manner, suggesting that 1,25(OH)₂D₃ inhibits scavenging function in macrophages. In order to clarify the mechanism of its inhibitory effect on degradation of acetyl LDL, we performed the ligand binding assay using ¹²⁵I-labeled acetyl LDL. Scatchard analysis revealed that 1,25(OH)₂D₃ decreased the number of scavenger receptors without changing the affinity for acetyl LDL. We next examined the effect of 1,25(OH)₂D₃ on the expression of scavenger receptor mRNA. The mRNA of type I scavenger receptor was first detected in THP-1 cells 4 days after the treatment with TPA, the mRNA level increased up to 6 days, and then decreased. The treatment with 1,25(OH)₂D₃ for 72 h dramatically decreased the mRNA levels after the acquisition of macrophage phenotypes as evidenced by nonspecific esterase staining. However, 1,25(OH)₂D₃ did not affect the activity of non-specific esterase nor the induction of interleukin-1β mRNA by lipopolysaccharide in THP-1 macrophages. These findings suggest that 1,25(OH)₂D₃ exclusively decreases the expression of scavenger receptors in TPA-induced THP-1 macrophages without affecting the basic cellular functions as macrophages. © 1995 Wiley-Liss Inc.     

Properties of Two N-Linked Glycoproteins Associated with the Nuclear Envelope in Mung Bean Hypocotyls

Nuclei from mung bean (Vigna radiata) hypocotyls contained twoglycoproteins of 50 and 49 kDa, respectively, that reacted withconcanavalin A. The glycoproteins were released from the nuclearenvelope by treatment with 2 M KCl but not with nucleases. Theglycoproteins, tentatively named gp50 and gp49, were isolatedand characterized. Gel-permeation chromatography suggested thatgp50 and gp49 seem to exist as a complex with other components.The glycoproteins could be detected only in the nuclear fractionby immunoblot analysis with specific antibodies, and they werenot detected in endoplasmic reticulum, plasma membrane, vacuolarmembrane or mitochondria. Agglutinin I from Ulex europeaus,peanut agglutinin, soybean agglutinin and wheat germ agglutininall failed to bind to the glycoproteins. Treatment with glycopeptidaseF removed all oligosaccharides from the glycoproteins and decreasedtheir molecular masses by about one thousand daltons each. Theseresults suggest that the glycoproteins contained N-linked, high-mannose-typeoligosaccharides with six or seven hexose residues. gp50 andgp49 seemed to be isoforms of a single glycoprotein becausethe two proteins had some common properties. Nuclear fractionsfrom azuki bean (Phaseolus angularis) and soybean (Glycine max)contained proteins that were immunologically similar to gp50and gp49. (Received March 18, 1995; Accepted May 24, 1995)