Electron microscope observations on the early development of the rat

Summary The early development of the rat, from the mature oocyte through fertilization until the 8-cell stage, has been studied with the electron microscope. The fine structure is described and discussed, with particular reference to the following topics. The middle piece of the spermatozoon is found in every stage studied, within the ovum cytoplasm; it is not significantly altered by this situation. The nucleoli are numerous during the 1-cell stage and often present in positions that suggest their extrusion into the cytoplasm; in subsequent stages a branching structure develops around them. The dividing cell presents the mitotic apparatus with its centrioles, hollow looking fibers, chromosomes, but without centromeres; in the cytoplasm the small granules align in rows. Mitochondria are evenly distributed during the 1-cell stage and can be found in the 8-cell stage constricted as if dividing. The multivesicular bodies constitute an abundant population of cytoplasmic elements that may be related to the endoplasmic reticulum or the Golgi complex, neither of which is clearly recognizable. In the 8-cell stage the cytoplasm segregates into two zones, one of which contains all the multivesicular bodies, while the mitochondria are found in both of them; this distinction provides some basis to adscribe to the multivesicular bodies the properties of the so called metachromatic particles.The support of the Gildemeister Foundation is gratefully acknowledged.     

On the fine structure of the aglomerular renal tubule in Lophius piscatorius

Summary The fine structure of the secretory tubules in the kidney of the aglomerular goose-fish (Lophius piscatorius) is described. The cells have a pyramidal shape, are joined together by multiple desmosomes, and share as main characteristics: abundant and deep inflections of the basal and lateral cell membranes; coated luminal plasma membranes forming multiple microvilli or a genuine brush border; moderate numbers of comparatively small mitochondria, usually unassociated with the basal and lateral plasma membrane specializations; numerous multivesicular bodies occuring in the apical cytoplasm; abundant large lysosome-like bodies in the intermediate regions of the cytoplasm; and comparatively poor development of endoplasmic reticulum and Golgi apparatus.The observations suggest that the cells perform both absorptive and secretory functions and are metabolically unusually active in autolytic and heterolytic work. Comparisons with other aglomerular species indicate that the ability for active secretory function is not necessarily dependent on a close association between plasma membrane and mitochondria; however, this ability does appear to require a markedly increased basal and/or lateral cell surface created by multiple invaginations of the plasma membrane. The abundance of desmosomes and associated structures appears to represent a unique structural specialization of the goosefish tubule, and indicates that the cells must be firmly anchored to one another to supply a rigid and mechanically continuous lining of the tubule. The multivesicular bodies probably represent endocytic vacuoles which fuse with apical vesicles and invaginate their outer membrane to form the internal vesicles; they appear to transform to ambilysosomes via a function as heterophagosomes and — later — combined hetero- and autophagosomes.Supported by grants from Karolinska Institutet, Fonden til Videnskabens Fremme and Konsul Johannes Fogh-Nielsen og fru Ella Fogh-Nielsens Légat. Part of the study was performed at the Zoological Station at Naples, Italy. The assistance of Mrs. Britt-Marie Karlsson is gratefully acknowledged.     

The development of synapses in vitro between previously dissociated chick spinal cord neurons

Summary The formation and development of synaptic contacts between dissociated chick spinal cord neurons has been investigated. By the 6th day in vitro immature profiles with few vesicles were observed. By 14–18 days mature types with numerous vesicles were found, indistinguishable from those of newly hatched chick spinal cord. After this period degeneration occurred, and was especially marked in the post-synaptic element. Such degeneration could be postponed by the addition of small numbers of somatic muscle cells. The Kanaseki and Kadota (1969) technique was applied to the study of coated vesicles at various stages of synaptic development.     

Meiotic studies ofElymus nutans andE. jacquemontii (Poaceae,Triticeae) and their hybrids withPseudoroegneria spicata and seventeenElymus species

Hybridizations ofElymus nutans andE. jacquemontii were carried out with one species ofPseudoroegneria (S genome), and 20Elymus species, each containing either of the SH, SY, SYH, or SYW genomes. Chromosome configurations were analysed at metaphase I of the two target taxa and their interspecific hybrids. It is concluded that (i)E. nutans is an allohexaploid containing the SYH genomes, andE. jacquemontii is an allotetraploid having the SY genomes; (ii) the genomic affinity is associated with the geographic distance between the species studied; (iii) minor genomic structural rearrangements have occurred within the hexaploid taxon ofE. nutans.     

The endomembrane system of differentiating carposporangia in the red algaChondria tenuissima: Occurrence and participation in secretion of polysaccharidic and proteinaceous substances

Summary The endomembrane system during carposporogenesis inChondria tenuissima was studied using electron microscopy and histochemistry. Profiles of the nucleus are convoluted, resulting in a highly increased surface area. Stacked cisternae are found within the peripheral part of the nucleus. Vesicles, tubules and membrane bound fibrillar bodies occur within the nucleoplasm. The endoplasmic reticulum surrounds the nuclear envelope.The endoplasmic reticulum and the Golgi apparatus, together with small transition vesicles, represent a functional unit. They form two different secretory substances during carposporogenesis. In young stages, carbohydrates are produced by normal dictyosomes within large, normal exocytotic Golgi vesicles. They do not react positively with PAS or Thiéry method and are believed to represent cell wall material. In later stages, the central area of the Golgi cisternae becomes filled with electron dense material. The individual cisternae are transformed into cored vesicles at the trans-face of the dictyosomes. The dense core of the vesicles is proteinaceous and stains with coomassie brilliant blue R. The peripheral fibrillar material is polysaccharidic and reacts positively using the Thiéry method. The contents of the cored vesicles are believed to participate in carpospore attachment. The ER gives rise to cytolysosomes in which starch grains are sequestrated and digested. Mucilaginous sacs seem to be similarly formed.     

Effects of G-protein probes on interactions between auxin efflux carriers and phytotropin receptors in zucchini (Cucurbita pepo L.) microsomal membranes

Microsomal vesicles prepared from etiolated hypocotyl tissue of zucchini (Cucurbita pepo L. cv. All Green Bush) exhibited saturable N-1-naphthylphthalamic acid ([³H]NPA) binding, NPA-stimulated association of indol-3yl-acetic acid ([³H]IAA), and saturable binding of guanosine 5-O-[3-thiotriphosphate] (GTP--[³⁵S]). These vesicles were used to test the possibility that NPA receptors might interact with IAA-anion efflux carriers by coupling through a GTP-binding protein (G-protein). Unlabelled GTP--S or guanosine 5-O-[2-thiodiphosphate] (GDP--S) had no effect on saturable NPA binding or on the NPA-stimulated association of IAA with microsomes. NPA did not affect saturable binding of GTP--[³⁵S] to microsomes, either in the presence or absence of saturating concentrations of unlabelled GTP--S or GDP. It is concluded that the occupancy of phytotropin receptors is not transduced to auxin efflux carriers by a GTP-binding protein.     

Alpha-factor leader sequence-directed transport of Escherichia coli beta-galactosidase in the secretory pathway of Saccharomyces cerevisiae

Summary The constuction of two fused genes is described. One involves the in-frame fusion of the yeast prepro--factor coding sequence, and the Escherichia coli lac Z gene. The second gene fusion utilizes a 103 bp yeast invertase NH₂-terminal coding sequence at the fusion junction of the hybrid gene described above. The gene fusions, under the control of the -factor promoter, expressed active -galactosidase in haploid yeast cells. The activity could be regulated in a temperature-sensitive sir3 mutant. The incorporation of the invertase coding sequence at the MF1-lacZ fusion junction provided significantly higher levels of -galactosidase activity. A substantial quantity of the hybrid proteins generated from the gene fusions was primarily localized in the intracellular membranes of yeast cells, while a processed form could be secreted into the periplasm.A portion of this work appeared in Biotechnology Progress (Das and Shultz 1986) as proceedings of the symposium on Industrial Scale Protein Purification, held at the annual meeting of the Institute of Chemical Engineers in Miami Beach, Fla, USA on November 4, 1986     

Electrostatic surface properties of plasmalemma vesicles from oat and wheat roots. Ion binding and screening investigated by 9-aminoacridine fluorescence

Right-side-out and sealed plasmalemma vesicles were isolated from roots of spring wheat (Triticum aestivum L. cv. Drabant) and oat (Avena sativa L. cv. Brighton) by two-phase partition in a medium containing sucrose (0.25 mol l^-1). Oat root plasmalemma vesicles were discovered to contain a strongly fluorescent compound with an emission maximum at 418 nm. The surface potential of the membranes was monitored by 9-aminoacridine fluorescence and the effect of protein concentration, mannitol versus sucrose, absence of osmoticum, concentrations of salt, and titrations with chelators investigated. It is concluded that i) protein concentrations of less than 50 g ml^-1 for oat and 100 g ml^-1 for wheat plasmalemma vesicles should be used to avoid serious problems with non-linearity of response of 9-aminoacridine fluorescence, ii) mannitol can be used instead of sucrose as the osmoticum, iii) the vesicles were ruptured in the absence of osmoticum allowing us to monitor both sides of the membranes, iv) plasmalemma vesicles from oat roots are more negative than vesicles from wheat roots, and v) oat and wheat root plasmalemma vesicles are isolated with about the same amounts of bound Ca²⁺ and Mg²⁺. These bound divalent cations may not, however, reflect the in-vivo conditions since the tissues were homogenised in the presence of ethylenediaminetetraacetic acid.Abbreviations EDTA ethylenediaminetetraacetic acid - EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - c1/2 value concentration at which half of the maximum effect is observed - Mops 3-(N-morpholino)propanesulfonic acid     

Ultrastructure of differentiating hemocytes in the embryo of Oncopeltus fasciatus Dallas (Insecta,Heteroptera)

Summary The hemocytes of Oncopeltus differentiate rather early during embryogenesis. They are segregated by the mesoderm soon after its formation (about 50h after egg deposition). Newly segregated hemocytes show the typical features of embryonic cells: many free ribosomes, a few strands of rough ER, the cisternae of which are considerably distended, electron lucent vacuoles around the periphery, and glycogen deposits. A few hours thereafter the hemocytes undergo striking subcellular changes. First, glycogen, electron lucent vacuoles and rough ER disappear and phagocytotic activity can be observed. Golgi complexes become well expressed and give rise to electron dense vesicles which fuse to larger bodies. Then, rough ER develops again and occupies large areas of the cytoplasm. Its cisternae are often considerably distended by proteinaceous secretions. All hemocytes undergo the same steps of differentiation.Embryonic hemocytes obviously play a decisive role in the elimination of waste products, in particular of tissue debris that results from programmed cellular death. The significance of the conspicuous protein secretions is not fully understood. They may participate in the deposition of the acellular connective tissue, or may have some of the other functions ascribed to insect blood cells.Larvae and imagines of Oncopeltus have four types of hemocytes, which agree rather well with those found in Rhodnius (Lai-Fook, 1970). All embryonic hemocytes, aside from the newly segregated ones, represent plasmatocytes but, unlike plasmatocytes of postembryonic stages, they contain no large inclusion bodies. Newly segregated embryonic hemocytes, in addition to their typical embryonic features, have some similarities with larval and adult prohemocytes. Oenocytoids and granulocytophagous cells are absent in the embryo. Some aspects concerning the differentiation and classification of hemocytes are discussed.Supported by research grant Do 163 from the Deutsche ForschungsgemeinschaftThe author is grateful to Ms. K. Schmidtke and Ms. M. Ullmann for technical assistance     

Histochemical studies on the distribution of β-glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of the rat

Summary The present study compares the distribution of -glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of rat. In young cells there are indications of cyclic activity of these enzymes, i.e., in some stages there are perinuclear concentrations of the enzymes, at other times -glucuronidase and succinic dehydrogenase are uniformly distributed throughout the cytoplasm. These stages have been discussed with the identical distribution of mitochondria. However, in old spinal ganglion cells both -glucuronidase and succinic dehydrogenase become mainly concentrated in the pigment areas, suggesting thereby their possible role in the production of pigment, through the medium of the mitochondria.     

Role of mitochondria in ethanol tolerance of Saccharomyces cerevisiae

The presence of active mitochondria and oxidative metabolism is shown to be essential to maintain low inhibition levels by ethanol of the growth rate (), fermentation rate (v) or respiration rate () of Saccharomyces cerevisiae wild type strain S288C. Cells which have respiratory metabolism show K _i (ethanol inhibition constant) values for , v and , higher (K _i>1 M) than those of petite mutants or grande strains grown in anaerobiosis (K _i=0.7 M). In addition, the relationship between or v and ethanol concentration is linear in cells with respiratory metabolism and exponential in cells lacking respiration. When functional mitochondria are transferred to petite mutants, the resulting strain shows K _i values similar to those of the grande strain and the inhibition of and v by increasing ethanol concentrations becomes linear.     

Xanthophores in chromatophore groups of the premigratory neural crest initiate the pigment pattern of the axolotl larva

Summary The barred pigment pattern (Lehman 1957) of the axolotl larva is best observed from stage 41 onwards, where it already consists of alternating transverse bands of melanophores and xanthophores along the dorsal side of the trunk. The present study investigateswhen the two populations of neural crest derived chromatophores, melanophores and xanthophores become determined andhow they interact to create the barred pigment pattern. The presence of phenol oxidase (tyrosinase) in melanophores (revealed by dopa incubation) and pteridines in xanthophores (visualized by fluorescence) were used as markers for cell differentiation in order to recognize melanophores and xanthophores before they became externally visible. It was found that melanophores and xanthophores were already determined in the premigratory neural crest, at stages 30/31 and 35–36, respectively. Between stages 35–36 and 38 they were arranged in a prepattern of several distinct, mixed chromatophore groups along the dorsal trunk, morphologically correlated in the scanning electron microscope with humps on the original crest cell string. While the occurrence of xanthophores was restricted to the chromatophore groups and around them, melanophores were already uniformly distributed in the dorsolateral flank area, having migrated from trunk neural crest portions including the groups. The bar component of the pigment pattern was subsequently initiated by xanthophores, which caused melanophores in and around the chromatophore groups to fade or become invisible. The barred pattern was established by the formation of alternating clusters of like cells, melanophores and xanthophores.     

Comparison of [35S]GTPγS binding to plasma membranes and endomembranes prepared from soybean and rat

Summary Plasma membranes were prepared from soybean hypocotyls and roots by aqueous two-phase partitioning and subsequent free-flow electrophoresis. The highly purified plasma membranes bound [³⁵S]GTPS with a relatively high affinity (K_d10nM). The binding was saturable and specific as it was indicated by the displacement of bound [³⁵S]GTPS by unlabeled GTPS and GTP, but not by ATPS, ATP, UTP or CTP. ITP was intermediate in its ability to displace [³⁵S]GTPS. When soybean plasma membrane proteins were separated by SDS-PAGE and displayed by autoradiography, two major [³⁵S]GTPS binding proteins were revealed with apparent molecular weights of 24 and 28 kDa. Results with plasma membranes from soybean hypocotyls and roots were similar but differed from those with plasma membranes prepared from rat liver and adipocytes where only a single major [³⁵S]GTPS binding activity with a molecular weight of 28 kDa was observed.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - G protein hetero-trimeric GTP binding protein with , , subunits - G_n protein GTP binding protein detected on nitrocellulose blots - GTPS guanosine 5-[-thio]triphosphate - IAA 3-indoleacetic acid - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis     

Ultrastrukturen der zellulären Autophagie

Zusammenfassung Im Laufe der Cytoplasmareduktion während der Spermiogenese von Eisenia foetida sind zwei Vorgänge zu unterscheiden: 1. Die Bildung autophagischer Vakuolen. Sie entstehen, indem Teile des Grundcytoplasmas in das Kompartiment des ER verlagert werden. Da sie keine Reaktion auf saure Phosphatase geben, sind sie als nicht lysosomale Anfangstadien der zellulären Autophagie zu betrachten. 2. Die Bildung primärer Lysosomen. Sie entstehen in Form von lytische Enzyme enthaltenden Golgivesikeln, die von einer neu im Cytoplasma entstehenden Membran zu größeren Einheiten zusammengefaßt werden: den multivesicular bodies. Autophagische Vakuolen und multivesicular bodies gelangen ins Cytophor das am Ende der Spermiogenese den Charakter eines ausgedehnten Autophagosoms annimmt. Als Struktureigentümlichkeit entstehen in ihm undulierende Tubulikörper. Der coat an den Hüllmembranen junger multivesicular bodies und am Plasmalemm der Spermatidenverbindung zum Cytophor wird in Zusammenhang mit der Membrandifferenzierung diskutiert.

---

Ultrastructural equivalents of cellular autophagyElectronmicroscopical observations on spermatids of Eisenia foetida during the cytoplasmic reduction

Summary During the cytoplasmic reduction phase in the spermiogenesis of Eisenia foetida two different processes may be defined: 1. The formation of autophagic vacuoles, which arise by the displacement of cytoplasmic portions into the cisternae of the endoplasmic reticulum. Since they exhibit no acid phosphatase activity they are considered to be early stages in cellular autophagy. 2. The formation of primary lysosomes. They originate in Golgi vesicles and are then enveloped by a membrane, formed in the cytoplasm de novo, which transforms them into multivesicular bodies. Autophagic vacuoles and multivesicular bodies subsequently transfer to the cytophor, which contains at the end of the spermiogenesis the characteristics of a large autophagosom, showing aggregates of undulating tubules. The outer coat of the limiting membranes in the early multivesicular bodies and of the cell membrane of the connecting piece between spermatid and cytophor appear to be associated with the membrane development.

     

Expression of gloshedobin,a thrombin-like enzyme from the venom of Gloydius shedaoensis,in Escherichia coli

Gloshedobin, a thrombin-like enzyme from the venom of Gloydius shedaoensis, was expressed in Escherichia coli using expression vector pET-32a(+). The gene was expressed under T7 promotor with a fusion partner of Thx.Tag and a 6xHis.Tag at its 5 terminal. After induction by IPTG for 6 h, the recombinant enzyme was expressed in the cytoplasm. Expression at 25°C gave twice the amount of recombinant gloshedobin in cytoplasm than at 37°C.     

Characterization of two beta-tubulin genes from Geotrichum candidum.

Summary The -tubulin genes G1 and G2 from the phytopathogenic hemiascomycete Geotrichum candidum were found to be highly diverged in amino acid sequence from those of other filamentous fungi. G1 and G2 were also divergent from each other, with the coding regions sharing only 66% nucleotide sequence homology and 64% amino acid identity. However, the proteins shared 82% similarity and only 25 of the 161 non-identical amino acid substitutions were non-conservative. The organization of G1 is similar to other fungal -tubulin genes, but G2 has several unusual features; it has 2 amino acid additions in the N-terminal 40 residues and must employ an uncommon 5 splice junction sequence in preference to an overlapping perfect consensus. The amino acid change found to confer benomyl resistance in Neurospora crassa was also present in G2. G1 has four introns which are located similarly to those of -tubulin genes in other fungi. G2, however, has a single intron in a unique location. Translational fusions employing the 5 non-coding regions of the two Geotrichum -tubulin genes were made with the hygromycin phosphotransferase gene and shown to function in Schizosaccharomyces pombe and Trichoderma hamatum. However, G. candidum could not be transformed with these or other tested plasmids commonly used for fungal transformation.     

Changes in density of chromatin in the meristematic cells ofSinapis alba during transition to flowering

Summary Changes in the density of nuclear chromatin in the shoot apical meristem ofSinapis alba L. during floral transition (floral evocation) are described using Feulgen-stained 2 m thick semi-thin sections and scanning cytophotometric techniques. In both G1 and G2 nuclei the chromatin becomes less heterogeneous and less dense in evoked meristems compared to vegetative meristems. When chromatin is resolved into two fractions the dispersed fraction increases relative to the condensed fraction at evocation. This decondensation process occurs earlier in G1 than in G 2 nuclei. These chromatin changes are presumably closely related to the dramatic stimulation of biosynthetic activity and cell division during floral transition.     

Cytokinesis in the green alga Eremosphaera viridis: Plasmalemma formation from “open membranes”

Summary Cytokinesis in the unicellular chlorococcalean alga Eremosphaera viridis de Bary has been investigated by electron microscopy of thin sections. The new plasmalemmata of the daughter cells in this organism form centrifugally within a phycoplast. Unlike other cell division systems each new plasmalemma is formed, not by the fusion of vesicles, but rather by the fusion of open membranes which are characteristically heavily stained. Measurements of these open membranes reveal that they are 11 nm thick with a central 4,5 nm unstained portion. The possible origin of these open membranes as burst-open vesicles has been suggested from the presence of intensely straining vesicles in the vicinity of the cell equator. Calculations of vesicle and open membrane surface areas support this contention.     

Proteolysis alters the spectral properties of 124 kdalton phytochrome from Avena

Native phytochrome from Avena sativa L. is homogeneous with a monomeric molecular weight of 124 kdalton; 6–10 kdalton larger than the heterogeneous 120 kdalton preparations previously considered to be undegraded (Vierstra and Quail, 1982, Proc. Natl. Acad. Sci. USA, 79: 5272–5276). The phototransformation difference spectrum (Pr-Pfr) of 124 kdalton phytochrome measured in crude extracts has a minimum in the farred region at 730 nm, the same as that observed in vivo. These spectral properties contrast with those of 120 kdalton phytochrome purified by column immunoaffinity chromatography where the difference minimum is at 724 nm. When 124 kdalton phytochrome is incubated as Pr in crude extracts, the difference minimum shifts progressively to shorter wavelengths (from 730 to 722 nm) concomitant with the proteolytic degradation of the chromoprotein to the mixture of 118 and 114 kdalton species that comprise 120 kdalton phytochrome preparations. These two effects are inhibited in concert by the serine protease inhibitor, phenylmethylsulfonylfluoride, and or maintenance of the phytochrome in the Pfr form. These results provide further evidence that 124 kdalton phytochrome is the native molecule in Avena and indicate that the peptide segments removed by proteolysis of the Pr form are important to the pigment's spectral integrity. The present data thus resolve the previously unsettled question of why the Pfr form of 120 kdalton phytochrome isolated by various procedures from Avena has been found to absorb at shorter wavelengths than that observed in vivo. Previous spectral studies with 120 kdalton phytochrome preparations are open to reexamination.Abbreviations, symbols PMSF phenylmethylsulfonylfluoride - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - Ig immunoglobulin - A_minimum, A_maximum phototransformation difference spectrum (Pr-Pfr) minimum and maximum - A_r/A_fr ratio spectral change ratio     

Exploration and exploitation of soil by apple,kiwifruit, peach,Asian pear and grape roots

Measurements of root-length density (RLD) in a range of 31 apple, kiwifruit, peach, Asian pear and grape orchards were used to derive indices to describe the exploration and exploitation of rooting volumes. Orchards were of various ages and located on a range of soil types, geographic regions, management systems etc. Data were obtained from core samples of volume 1.66×10^-4 m³ randomly taken within a standard volume, determined by average planting grids, of 2 m radius centred on tree stems, and 1 m depth. Root systems were described using an exploitation index, E(), and an exploration index, E(0). E() is defined as the proportion of the soil volume which contains roots at RLD greater than or equal to some specified value, . E(0) is defined as the proportion of the soil volume which contains roots at any RLD greater than zero. These indices are dependent on sample size, as are all volumetric or soil-coring data.Estimates of E(0) for each orchard were obtained as the proportions of cores containing any RLD>O and assessed for dependence on species. Peach trees had a significantly higher value of E(0), equal to almost 1.0, compared to the other four species where E(0) was approximately 0.8 (p0.01) or less. There was also some variation with age. E(0) was lower for very young plants which had not fully occupied the sampled soil volume. Exploration indices for woody roots increased with rootstock age but otherwise did not explain large differences in E() between species for given values.For example at =0.05×10⁴ m.m^-3, E() was approximately 0.45 for peach and kiwifruit, and 0.05 for apple, Asian pear and grape, whereas at =0.5×10⁴ m.m^-3 the corresponding values were 0.1 and almost zero. Negative exponential curves relating E(), scaled by dividing by E(0), to were fitted for each of the 31 orchards. Exponents for these curves, k, were significantly smaller for kiwifruit and peaches than apples, grapes and Asian pears (p0.05), and smaller for apples than grapes and Asian pears (p0.05). A larger k implies a rapid fall-off in E() as increases. Although all five species contained zero and low RLD samples, only kiwifruit and peaches contained higher RLD values and consequently have higher mean RLD. This trend was consistent across all soils, regions, sampling dates, and plant ages.The analyses demonstrate that core sampling can give useful insights into macro-scale root-system distribution, such as the proportion of a soil volume explored and how it is exploited. If positions of core samples are noted during sampling using angular direction, depth and radial distance as spatial coordinates the method can be used to describe root-system structures.