The Effects of Agitated Liquid Medium on in vitro Cultures of Hevea brasiliensis

The initiation and prolonged growth of callus, from stem explants of young plants of Hevea brasilienies on solid medium yielded a heterogeneous callus, with areas which are the result of compact growth interspersed with brown necrotic tissue and soft white tissue formations. Subculturing this callus (O callus) to agitated liquid medium and returning it to solid medium resulted in the production of a homogeneous friable and rapidly growing callus (Rl callus) The two established lines O and Rl have remained stable over one year in culture and differ in gross morphology, anatomy, growth and auxin content. Both were maintained on Murashige and Skoog's medium, with 2 mg/1 2,4-D and 0.5 mg/I kinetin. R 1 but not O showed enhanced growth at the lower 2,4-D level of 0.2 mg/l: both lines failed to continue growing when 2,4-D was omitted. It is suggested that the changes resulting from subculture in agitated liquid medium are related to those undergone by callus cultures which become habituated. Thus the Rl callus line is regarded as partially habituated. Subculture in agitated liquid medium also resulted in the production of large numberr of polyploid cells but these did not persist over the long periods of subsequent growth on agar medium, Enhanced auxin production by the establihed Rl callus line was thus observed in the absence of a detectable level of polyploidy.     

Characterization of the Malaria Pigment (Hemozoin) from the Avian Malaria Parasite Plasmodium lophurae*

SYNOPSIS. Plasmodium lophurae hemozoin (malaria pigment) is a heme-containing protein which is distinctly different from hemoglobin and hematin by immunologic, spectrophotometric, fingerprint, heme-iron, gel filtration, and starch gel electrophoretic analyses. The calculated average molecular weight of P. lophurae hemozoin is ca. 40,000. Hemozoin contains at least 3 antigenic components and shows some indication of cross-reaction with hemoglobin.     

Mismatches between breeding success and habitat preferences in Hen Harriers Circus cyaneus breeding in forested landscapes

During the past century, the upland breeding areas of Hen Harriers in Ireland have been extensively afforested. There is no evidence that this species avoids breeding in heavily forested landscapes and, indeed, young commercial forests in their second rotation are often selected as nest‐sites. However, Hen Harriers have coexisted with these forested areas for only a few decades and it is possible that such landscapes are suboptimal. We examined the relationship between breeding success and habitat using a dataset spanning three years and four study areas in the south and west of Ireland. We assessed whether nest success and fledged brood size were related to habitat type, both at the nest‐site and in the surrounding landscape. Neither measure of breeding productivity was related to total forest cover or to percentage cover of closed canopy forest in the landscape. However, in a subset of areas, high cover of second‐rotation pre‐thicket (young forests planted on land from which a first rotation has already been harvested) in the surrounding landscape was associated with low levels of breeding success. This may be due to factors related to predation, disturbance or prey availability. The fact that second‐rotation pre‐thicket is a preferred habitat for nesting in Ireland suggests that Hen Harriers may be making suboptimal decisions in the landscapes available to them.     

Incipient ring speciation revealed by a migratory divide

Ever since Ernst Mayr (1942) called ring species the ‘perfect demonstration of speciation’, they have attracted much interest from researchers examining how two species evolve from one. In a ring species, two sympatric and reproductively isolated forms are connected by a long chain of intermediate populations that encircle a geographic barrier. Ring species have the potential to demonstrate that speciation can occur without complete geographic isolation, in contrast to the classic model of allopatric speciation. They also allow researchers to examine the causes of reproductive isolation in the contact zone and to use spatial variation to infer the steps by which speciation occurs. According to the classical definition, a ring species must have (i) gradual variation through a chain of populations connecting two divergent and sympatric forms, and (ii) complete or nearly complete reproductive isolation between the terminal forms. But evolutionary biologists now recognize that the process of speciation might often occur with some periods of geographic contact and hybridization between diverging forms; during these phases, even partial reproductive isolation can limit gene flow and permit further divergence to occur. In this issue Bensch et al. (2009) make an exciting and important contribution by extending the ring species concept to a case in which the divergence is much younger and not yet advanced to full reproductive isolation. Their study of geographic variation in willow warblers (Phylloscopus trochilus; Fig. 1 ) provides a beautiful example of gradual variation through a ring of populations connecting two forms that are partially reproductively isolated where they meet, possibly due to divergent migratory behaviours of the terminal forms.

Figure 1 Open in figure viewer PowerPoint A male willow warbler resembling the southeastern‐migrating form (Phylloscopus trochilus acredula), on its breeding territory in central Sweden. (Photo: Anders Hedenström).     

Revisions of Rump Fat and Body Scoring Indices for Deer,Elk, and Moose

Abstract: Because they do not require sacrificing animals, body condition scores (BCS), thickness of rump fat (MAXFAT), and other similar predictors of body fat have advanced estimating nutritional condition of ungulates and their use has proliferated in North America in the last decade. However, initial testing of these predictors was too limited to assess their reliability among diverse habitats, ecotypes, subspecies, and populations across the continent. With data collected from mule deer (Odocoileus hemionus), elk (Cervus elaphus), and moose (Alces alces) during initial model development and data collected subsequently from free-ranging mule deer and elk herds across much of the western United States, we evaluated reliability across a broader range of conditions than were initially available. First, to more rigorously test reliability of the MAXFAT index, we evaluated its robustness across the 3 species, using an allometric scaling function to adjust for differences in animal size. We then evaluated MAXFAT, rump body condition score (rBCS), rLIVINDEX (an arithmetic combination of MAXFAT and rBCS), and our new allometrically scaled rump-fat thickness index using data from 815 free-ranging female Roosevelt and Rocky Mountain elk (C. e. roosevelti and C. e. nelsoni) from 19 populations encompassing 4 geographic regions and 250 free-ranging female mule deer from 7 populations and 2 regions. We tested for effects of subspecies, geographic region, and captive versus free-ranging existence. Rump-fat thickness, when scaled allometrically with body mass, was related to ingesta-free body fat over a 38–522-kg range of body mass (r² = 0.87; P < 0.001), indicating the technique is remarkably robust among at least the 3 cervid species of our analysis. However, we found an underscoring bias with the rBCS for elk that had >12% body fat. This bias translated into a difference between subspecies, because Rocky Mountain elk tended to be fatter than Roosevelt elk in our sample. Effects of observer error with the rBCS also existed for mule deer with moderate to high levels of body fat, and deer body size significantly affected accuracy of the MAXFAT predictor. Our analyses confirm robustness of the rump-fat index for these 3 species but highlight the potential for bias due to differences in body size and to observer error with BCS scoring. We present alternative LIVINDEX equations where potential bias from rBCS and bias due to body size are eliminated or reduced. These modifications improve the accuracy of estimating body fat for projects intended to monitor nutritional status of herds or to evaluate nutrition's influence on population demographics.     

Effect of Salinity on Germination and Seedling Growth of twoAtriplexspecies (Chenopodiaceae)

Salinity is one of the environmental factors that has a criticalinfluence on the germination of halophyte seeds and plant establishment.Salinity affects imbibition, germination and root elongation.However, the way in which NaCl exerts its influence on thesevital processes, whether it is through an osmotic effect ora specific ion toxicity, is still not resolved. Dimorphic seedsof the halophytesAtriplex prostrataandA. patulawere treatedwith various iso-osmotic solutions of NaCl and polyethyleneglycol (PEG). For each treatment, imbibition, germination rate,percent germination, germination recovery and nuclear area ofroot tip cells were compared. Higher concentrations of NaCl(-1.0 MPa) were more inhibitory to imbibition, germination andseedling root elongation than iso-osmotic PEG solutions. Allseeds recovered from a pre-treatment with -2.0 MPa NaCl andPEG solutions, except large seeds ofA. prostratawhich failedto germinate following transfer from -2.0 MPa NaCl. NaCl causeda greater increase in nuclear volume than iso-osmotic PEG solutions.These data suggest that the influence of NaCl is a combinationof an osmotic effect and a specific ion effect.Copyright 1998Annals of Botany Company Atriplex patula,Atriplex prostrata,cytophotometry, osmotic potential, salinity, seed germination.     

Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands

The alpha3 fucosyltransferase, FucT-VII, is one of the key glycosyltransferases involved in the biosynthesis of the sialyl Lewis X (sLex) antigen on human leukocytes. The sialyl Lewis X antigen (NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential component of the recruitment of leukocytes to sites of inflammation, mediating the primary interaction between circulating leukocytes and activated endothelium. In order to characterize the enzymatic properties of the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been expressed in Trichoplusia ni insect cells. The enzyme is capable of synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from 3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors demonstrate that FucT-VII is able to synthesize both di-fucosylated and tri-fucosylated structures from mono- fucosylated precursors, but preferentially fucosylates the distal GlcNAc within a polylactosamine chain. Furthermore, the rate of fucosylation of the internal GlcNAc residues is reduced once fucose has been added to the distal GlcNAc. These results indicate that FucT-VII is capable of generating complex selectin ligands, in vitro , however the order of fucose addition to the lactosamine chain affects the rate of selectin ligand synthesis.      

Effect of soybean canopy closure on landing rates of aphids with implications for restricting spread of soybean mosaic virus

Alate Aphis citricola and Myzocallis punctatus were caught more abundantly on horizontal ermine-lime canopy-level sticky traps in a closed soybean canopy than on similar traps in an open canopy. This is the first reported case in which more alate aphids were collected on traps in fields with relatively more ground cover. Capitophorus elaeagni were caught more abundantly on traps in relatively more open canopy, and Lipaphis erysimi, Rhopalosiphum maidis and Schizaphis graminum were collected in statistically similar numbers in open and closed canopies. Our trapping technique was designed in an attempt to collect only those aphids which would otherwise have landed on the soybean canopy. Landing rates differed among species; therefore, the efficacy of using ground cover manipulation to reduce spread of soybean mosaic virus would depend upon seasonal occurrence of the important local vector species.