PopulusPtERF85 Balances Xylem Cell Expansion and Secondary Cell Wall Formation in Hybrid Aspen

Secondary growth relies on precise and specialized transcriptional networks that determine cell division, differentiation, and maturation of xylem cells. We identified a novel role for the ethylene-induced Populus Ethylene Response Factor PtERF85 (Potri.015G023200) in balancing xylem cell expansion and secondary cell wall (SCW) formation in hybrid aspen (Populus tremula x tremuloides). Expression of PtERF85 is high in phloem and cambium cells and during the expansion of xylem cells, while it is low in maturing xylem tissue. Extending PtERF85 expression into SCW forming zones of woody tissues through ectopic expression reduced wood density and SCW thickness of xylem fibers but increased fiber diameter. Xylem transcriptomes from the transgenic trees revealed transcriptional induction of genes involved in cell expansion, translation, and growth. The expression of genes associated with plant vascular development and the biosynthesis of SCW chemical components such as xylan and lignin, was down-regulated in the transgenic trees. Our results suggest that PtERF85 activates genes related to xylem cell expansion, while preventing transcriptional activation of genes related to SCW formation. The importance of precise spatial expression of PtERF85 during wood development together with the observed phenotypes in response to ectopic PtERF85 expression suggests that PtERF85 contributes to the transition of fiber cells from elongation to secondary cell wall deposition.

An AP2/ERF transcription factor ERF139 coordinates xylem cell expansion and secondary cell wall deposition

Differentiation of xylem elements involves cell expansion, secondary cell wall (SCW) deposition and programmed cell death. Transitions between these phases require strict spatiotemporal control. The function of Populus ERF139 (Potri.013G101100) in xylem differentiation was characterized in transgenic overexpression and dominant repressor lines of ERF139 in hybrid aspen (Populus tremula × tremuloides). Xylem properties, SCW chemistry and downstream targets were analyzed in both types of transgenic trees using microscopy techniques, Fourier transform-infrared spectroscopy, pyrolysis-GC/MS, wet chemistry methods and RNA sequencing. Opposite phenotypes were observed in the secondary xylem vessel sizes and SCW chemistry in the two different types of transgenic trees, supporting the function of ERF139 in suppressing the radial expansion of vessel elements and stimulating accumulation of guaiacyl-type lignin and possibly also xylan. Comparative transcriptomics identified genes related to SCW biosynthesis (LAC5, LBD15, MYB86) and salt and drought stress-responsive genes (ANAC002, ABA1) as potential direct targets of ERF139. The phenotypes of the transgenic trees and the stem expression profiles of ERF139 potential target genes support the role of ERF139 as a transcriptional regulator of xylem cell expansion and SCW formation, possibly in response to osmotic changes of the cells.

Ethylene signaling induces gelatinous layers with typical features of tension wood in hybrid aspen

The phytohormone ethylene impacts secondary stem growth in plants by stimulating cambial activity, xylem development and fiber over vessel formation. We report the effect of ethylene on secondary cell wall formation and the molecular connection between ethylene signaling and wood formation. We applied exogenous ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) to wild-type and ethylene-insensitive hybrid aspen trees (Populus tremula × tremuloides) and studied secondary cell wall anatomy, chemistry and ultrastructure. We furthermore analyzed the transcriptome (RNA Seq) after ACC application to wild-type and ethylene-insensitive trees. We demonstrate that ACC and ethylene induce gelatinous layers (G-layers) and alter the fiber cell wall cellulose microfibril angle. G-layers are tertiary wall layers rich in cellulose, typically found in tension wood of aspen trees. A vast majority of transcripts affected by ACC are downstream of ethylene perception and include a large number of transcription factors (TFs). Motif-analyses reveal potential connections between ethylene TFs (Ethylene Response Factors (ERFs), ETHYLENE INSENSITIVE 3/ETHYLENE INSENSITIVE3-LIKE1 (EIN3/EIL1)) and wood formation. G-layer formation upon ethylene application suggests that the increase in ethylene biosynthesis observed during tension wood formation is important for its formation. Ethylene-regulated TFs of the ERF and EIN3/EIL1 type could transmit the ethylene signal.

Axillary buds are dwarfed shoots that tightly regulate GA pathway and GA-inducible 1,3-β-glucanase genes during branching in hybrid aspen

Axillary buds (AXBs) of hybrid aspen (Populus tremula×P. tremuloides) contain a developing dwarfed shoot that becomes para-dormant at the bud maturation point. Para-dormant AXBs can grow out after stem decapitation, while dormant AXBs pre-require long-term chilling to release them from dormancy. The latter is mediated by gibberellin (GA)-regulated 1,3-β-glucanases, but it is unknown if GA is also important in the development, activation, and outgrowth of para-dormant AXBs. The present data show that para-dormant AXBs up-regulate GA receptor genes during their maturation, but curtail GA biosynthesis by down-regulating the rate-limiting GIBBERELLIN 3-OXIDASE2 (GA3ox2), which is characteristically expressed in the growing apex. However, decapitation significantly up-regulated GA3ox2 and GA₄-responsive 1,3-β-glucanases (GH17-family; α-clade). In contrast, decapitation down-regulated γ-clade 1,3-β-glucanases, which were strongly up-regulated in maturing AXBs concomitant with lipid body accumulation. Overexpression of selected GH17 members in hybrid aspen resulted in characteristic branching patterns. The α-clade member induced an acropetal branching pattern, whereas the γ-clade member activated AXBs in recurrent flushes during transient cessation of apex proliferation. The results support a model in which curtailing the final step in GA biosynthesis dwarfs the embryonic shoot, while high levels of GA precursors and GA receptors keep AXBs poised for growth. GA signaling, induced by decapitation, reinvigorates symplasmic supply routes through GA-inducible 1,3-β-glucanases that hydrolyze callose at sieve plates and plasmodesmata.

Long and short photoperiod buds in hybrid aspen share structural development and expression patterns of marker genes

Tree architecture develops over time through the collective activity of apical and axillary meristems. Although the capacity of both meristems to form buds is crucial for perennial life, a comparative analysis is lacking. As shown here for hybrid aspen, axillary meristems engage in an elaborate process of axillary bud (AXB) formation, while apical dominance prevents outgrowth of branches. Development ceased when AXBs had formed an embryonic shoot (ES) with a predictable number of embryonic leaves at the bud maturation point (BMP). Under short days, terminal buds (TBs) formed an ES similar to that of AXBs, and both the TB and young AXBs above the BMP established dormancy. Quantitative PCR and in situ hybridizations showed that this shared ability and structural similarity was reflected at the molecular level. TBs and AXBs similarly regulated expression of meristem-specific and bud/branching-related genes, including CENTRORADIALIS-LIKE1 (CENL1), BRANCHED1 (BRC1), BRC2, and the strigolactone biosynthesis gene MORE AXILLARY BRANCHES1 (MAX1). Below the BMP, AXBs maintained high CENL1 expression at the rib meristem, suggesting that it serves to maintain poise for growth. In support of this, decapitation initiated outgrowth of CENL1-expressing AXBs, but not of dormant AXBs that had switched CENL1 off. This singles out CENL1 as a rib meristem marker for para-dormancy. BRC1 and MAX1 genes, which may counterbalance CENL1, were down-regulated in decapitation-activated AXBs. The results showed that removal of apical dominance shifted AXB gene expression toward that of apices, while developing TBs adopted the expression pattern of para-dormant AXBs. Bud development thus follows a shared developmental pattern at terminal and axillary positions, despite being triggered by short days and apical dominance, respectively.

A genome-wide screen for ethylene-induced ethylene response factors (ERFs) in hybrid aspen stem identifies ERF genes that modify stem growth and wood properties

Ethylene Response Factors (ERFs) are a large family of transcription factors that mediate responses to ethylene. Ethylene affects many aspects of wood development and is involved in tension wood formation. Thus ERFs could be key players connecting ethylene action to wood development. We identified 170 gene models encoding ERFs in the Populus trichocarpa genome. The transcriptional responses of ERF genes to ethylene treatments were determined in stem tissues of hybrid aspen (Populus tremula × tremuloides) by qPCR. Selected ethylene-responsive ERFs were overexpressed in wood-forming tissues and characterized for growth and wood chemotypes by FT-IR. Fifty ERFs in Populus showed more than five-fold increased transcript accumulation in response to ethylene treatments. Twenty-six ERFs were selected for further analyses. A majority of these were induced during tension wood formation. Overexpression of ERFs 18, 21, 30, 85 and 139 in wood-forming tissues of hybrid aspen modified the wood chemotype. Moreover, overexpression of ERF139 caused a dwarf-phenotype with altered wood development, and overexpression of ERF18, 34 and 35 slightly increased stem diameter. We identified ethylene-induced ERFs that respond to tension wood formation, and modify wood formation when overexpressed. This provides support for their role in ethylene-mediated regulation of wood development.

A comparative study of meiotic recombination in cattle (Bos taurus) and three wildebeest species (Connochaetes gnou, C. taurinus taurinus and C. t. albojubatus)

The karyotypic evolution in the family Bovidae is based on centric fusions of ancestral acrocentric chromosomes. Here, the frequency and distribution of meiotic recombination was analyzed in pachytene spermatocytes from Bos taurus (2n = 60) and 3 wildebeest species (Connochaetes gnou, C. taurinus taurinus and C. t. albojubatus) (2n = 58) using immunofluorescence and fluorescence in situ hybridization. Significant differences in mean numbers of recombination events per cell were observed between B. taurus and members of the genus Connochaetes (47.2 vs. 43.7, p < 0.001). The number of MLH1 foci was significantly correlated with the length of the autosomal synaptonemal complexes. The average interfocus distance was influenced by interference. The male recombination maps of bovine chromosomes 2 and 25 and of their fused homologues in wildebeests were constructed. A significant reduction of recombination in the fused chromosome BTA25 was observed in wildebeests (p = 0.005). This was probably caused by interference acting across the centromere, which was significantly stronger than the intra-arm interference. This comparative meiotic study showed significant differences among the species from the family Bovidae with the same fundamental number of autosomal arms (FNa = 29) which differ by a single centric fusion.

Subchromosomal karyotype evolution in Equidae

Equidae is a small family which comprises horses, African and Asiatic asses, and zebras. Despite equids having diverged quite recently, their karyotypes underwent rapid evolution which resulted in extensive differences among chromosome complements in respective species. Comparative mapping using whole-chromosome painting probes delineated genome-wide chromosome homologies among extant equids, enabling us to trace chromosome rearrangements that occurred during evolution. In the present study, we performed subchromosomal comparative mapping among seven Equidae species, representing the whole family. Region-specific painting and bacterial artificial chromosome probes were used to determine the orientation of evolutionarily conserved segments with respect to centromere positions. This allowed assessment of the configuration of all fusions occurring during the evolution of Equidae, as well as revealing discrepancies in centromere location caused by centromere repositioning or inversions. Our results indicate that the prevailing type of fusion in Equidae is centric fusion. Tandem fusions of the type telomere-telomere occur almost exclusively in the karyotype of Hartmann's zebra and are characteristic of this species' evolution. We revealed inversions in segments homologous to horse chromosomes 3p/10p and 13 in zebras and confirmed inversions in segments 4/31 in African ass, 7 in horse and 8p/20 in zebras. Furthermore, our mapping results suggested that centromere repositioning events occurred in segments homologous to horse chromosomes 7, 8q, 10p and 19 in the African ass and an element homologous to horse chromosome 16 in Asiatic asses. Centromere repositioning in chromosome 1 resulted in three different chromosome types occurring in extant species. Heterozygosity of the centromere position of this chromosome was observed in the kiang. Other subtle changes in centromere position were described in several evolutionary conserved chromosomal segments, suggesting that tiny centromere repositioning or pericentric inversions are quite frequent in zebras and asses.

Molecular insights into X;BTA5 chromosome rearrangements in the tribe Antilopini (Bovidae)

For a clade that includes Antilope, Gazella,Nanger and Eudorcas (Antilopinae), X;BTA5 translocation is a synapomorphy. Using a combination of fluorescence in situ hybridization (FISH) probes and polymerase chain reaction techniques, we provide (i) the first insight into the X;BTA5 architecture which differs in the species under study: Antilope cervicapra (genus Antilope), Gazella leptoceros (genus Gazella) and Nanger dama ruficollis (genus Nanger), (ii) determination of interstitial satellite DNA at the X;BTA5 junctions, and (iii) determination of repetitive sequences occupying constitutive heterochromatin of Xp arms in the studied species. The distribution of 2 repetitive DNA families in the centromeric regions of all chromosomes has been investigated by FISH with probes representing satellite I and satellite II DNA in all studied species. In this context, we discuss a markedly smaller centromere in the BTA5 (Y2) unfused chromosomes in males in the XY1Y2 determining system in comparison with other acrocentrics. An analysis of karyotypic data described in current published studies revealed a disparity with the data determined by FISH. In this report, we document chromosomal fusions in the 3 species mentioned resulting from FISH with painting probes prepared from cattle (Bos taurus). The number and chromosomal location of nucleolus organizer regions were determined by FISH. In the present study, we emphasize the importance of chromosomal rearrangement verification, particularly, if they are used for phylogenetic analysis.

Chilling of dormant buds hyperinduces FLOWERING LOCUS T and recruits GA-inducible 1,3-beta-glucanases to reopen signal conduits and release dormancy in Populus

In trees, production of intercellular signals and accessibility of signal conduits jointly govern dormancy cycling at the shoot apex. We identified 10 putative cell wall 1,3-β-glucanase genes (glucan hydrolase family 17 [GH17]) in Populus that could turn over 1,3-β-glucan (callose) at pores and plasmodesmata (PD) and investigated their regulation in relation to FT and CENL1 expression. The 10 genes encode orthologs of Arabidopsis thaliana BG_ppap, a PD-associated glycosylphosphatidylinositol (GPI) lipid-anchored protein, the Arabidopsis PD callose binding protein PDCB, and a birch (Betula pendula) putative lipid body (LB) protein. We found that these genes were differentially regulated by photoperiod, by chilling (5°C), and by feeding of gibberellins GA(3) and GA(4). GA(3) feeding upregulated all LB-associated GH17s, whereas GA(4) upregulated most GH17s with a GPI anchor and/or callose binding motif, but only GA(4) induced true bud burst. Chilling upregulated a number of GA biosynthesis and signaling genes as well as FT, but not CENL1, while the reverse was true for both GA(3) and GA(4). Collectively, the results suggest a model for dormancy release in which chilling induces FT and both GPI lipid-anchored and GA(3)-inducible GH17s to reopen signaling conduits in the embryonic shoot. When temperatures rise, the reopened conduits enable movement of FT and CENL1 to their targets, where they drive bud burst, shoot elongation, and morphogenesis.

Cytotypes of Kirk's dik-dik (Madoqua kirkii,Bovidae) show multiple tandem fusions

Madoqua kirkii, a miniature African antelope, is noted for extensive chromosomal variation that has been categorized in four distinct cytotypes (A-D). In this investigation, we analyzed the A cytotype (2n = 46, FN = 48) using a suite of molecular cytogenetic approaches that entailed (i) whole chromosome and subchromosomal painting by fluorescence in situ hybridization (FISH), (ii) the study of Madoqua centromeric-specific DNA derived from pooled DNA obtained from the centromeric regions of the acrocentric chromosomes, and (iii) DNA from the telomere:centromere junctions of tandemly fused chromosomes. DNA from these sources was used to probe for the persistence of interstitial satellite DNA and residual centromeric sequences in the tandem and centric fusion junctions by PCR and FISH. The analyses show centromeric sequences at two of the six tandem fusion junctions. These data, and those of hybrid specimens (A × B cytotypes) in conjunction with published information permitted an interpretation of the probable sequence of chromosomal rearrangements among the M. kirkii cytotypes. We discuss the findings in the context of chromosomal evolution in these antelopes, and the implications that these hold for ex-situ breeding programs of the species.

Different fusion configurations of evolutionarily conserved segments in karyotypes of Potamochoerus porcus and Phacochoerus africanus

The karyotype of the red river hog Potamochoerus porcus (2n = 34) differs from that of the domestic pig by the presence of 2 fusion chromosomes homologous to pig chromosomes 13/16 and 15/17. Moreover, chromosomes corresponding to pig chromosomes 13/16 and 1 are both acrocentric. Hybridization with region-specific painting probes confirmed tandem fusion of pig chromosomes 13 and 16, and a pericentric inversion of the pig chromosome 1p equivalent in P. porcus. The chromosome complement of the wart hog Phacochoerus africanus (2n = 34) differs from the pig karyotype in 2 centric fusions, 13/16 and 15/17. Karyotypic relationships among different Suidae species are discussed in the article. Besides fusions 13/16 and 15/17, which are common to several suids, another fusion of pig chromosomes 14 and 18 is suggested to exist in the karyotype of Sus cebifrons.

Karyotypic relationships among Equus grevyi, Equus burchelli and domestic horse defined using horse chromosome arm-specific probes

Using laser microdissection we prepared a set of horse chromosome arm-specific probes. Most of the probes were generated from horse chromosomes, some of them were derived from Equus zebra hartmannae. The set of probes were hybridized onto E. grevyi chromosomes in order to establish a genome-wide chromosomal correspondence between this zebra and horse. The use of arm-specific probes provided us with more information on the mutual arrangement of the genomes than we could obtain by means of whole-chromosome paints generated by flow sorting, even if we used reciprocal painting with probe sets from both species. By comparison of our results and results of comparative mapping in E. burchelli, we also established the chromosomal correspondence between E. grevyi and E. burchelli, providing evidence for a very close karyotypic relationship between these two zebra species. Establishment of the comparative map for E. grevyi contributes to the knowledge of the karyotypic phylogeny in the Equidae family.

Karyotype, centric fusion polymorphism and chromosomal aberrations in captive-born mountain reedbuck (Redunca fulvorufula)

Chromosomes of fourteen captive-born mountain reedbucks (Redunca fulvorufula) have been investigated. The diploid chromosome number was 2n = 56 (FN = 60). The mountain reedbuck karyotype consists of 26 acrocentric and two biarmed chromosome pairs resulting from two centric fusions involving chromosomes 2 and 25, and 6 and 10, respectively. In some animals, 57 chromosomes were detected. Variation in the diploid number was found to be due to polymorphism for the centric fusion 6;10. Both X and Y chromosomes are large and acrocentric. The entire Y chromosome and the proximal part of the X chromosome consist of heterochromatin. The chromosomes X, 9 and 14 appeared to be of caprine type. Chromosome aberrations have been detected in two of the 14 animals investigated. A de novo formed Robertsonian translocation rob(6;13) was found in one female heterozygous for the fusion 6;10. CBG-banding revealed one block of centromeric heterochromatin in the de novo formed translocation rob(6;13) and also in the evolutionarily fixed centric fusions 6;10 and 2;25. One examined male homozygous for fusion 6;10, had a mosaic 56,XY/57,XYY karyotype, with 11% of analyzed cells containing two Y chromosomes. The findings were confirmed by cross-species fluorescence in situ hybridization (FISH) with bovine (Bos taurus L.) chromosome painting probes. The study demonstrates the relevance of cytogenetic screening in captive animals from zoological gardens.

The genome of black cottonwood, Populus trichocarpa (Torr. & Gray)

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.

Ethylene insensitivity modulates ozone-induced cell death in birch

We have used genotypic variation in birch (Betula pendula Roth) to investigate the roles of ozone (O(3))-induced ethylene (ET), jasmonic acid, and salicylic acid in the regulation of tissue tolerance to O(3). Of these hormones, ET evolution correlated best with O(3)-induced cell death. Disruption of ET perception by transformation of birch with the dominant negative mutant allele etr1-1 of the Arabidopsis ET receptor gene ETR1 or blocking of ET perception with 1-methylcyclopropene reduced but did not completely prevent the O(3)-induced cell death, when inhibition of ET biosynthesis with aminooxyacetic acid completely abolished O(3) lesion formation. This suggests the presence of an ET-signaling-independent but ET biosynthesis-dependent component in the ET-mediated stimulation of cell death in O(3)-exposed birch. Functional ET signaling was required for the O(3) induction of the gene encoding beta-cyanoalanine synthase, which catalyzes detoxification of the cyanide formed during ET biosynthesis. The results suggest that functional ET signaling is required to protect birch from the O(3)-induced cell death and that a decrease in ET sensitivity together with a simultaneous, high ET biosynthesis can potentially cause cell death through a deficient detoxification of cyanide.

Differential effects of elevated ozone on two hybrid aspen genotypes predisposed to chronic ozone fumigation. Role of ethylene and salicylic acid

The role of ethylene (ET) signaling in the responses of two hybrid aspen (Populus tremula L. x P. tremuloides Michx.) clones to chronic ozone (O(3); 75 nL L(-1)) was investigated. The hormonal responses differed between the clones; the O(3)-sensitive clone 51 had higher ET evolution than the tolerant clone 200 during the exposure, whereas the free salicylic acid concentration in clone 200 was higher than in clone 51. The cellular redox status, measured as glutathione redox balance, did not differ between the clones suggesting that the O(3) lesions were not a result of deficient antioxidative capacity. The buildup of salicylic acid during chronic O(3) exposure might have prevented the up-regulation of ET biosynthesis in clone 200. Blocking of ET perception with 1-methylcyclopropene protected both clones from the decrease in net photosynthesis during chronic exposure to O(3). After a pretreatment with low O(3) for 9 d, an acute 1.5-fold O(3) elevation caused necrosis in the O(3)-sensitive clone 51, which increased substantially when ET perception was blocked. The results suggest that in hybrid aspen, ET signaling had a dual role depending on the severity of the stress. ET accelerated leaf senescence under low O(3), but under acute O(3) elevation, ET signaling seemed to be required for protection from necrotic cell death.

Fecal progesterone, estrogen, and androgen metabolites for noninvasive monitoring of reproductive function in the female Indian rhinoceros, Rhinoceros unicornis

This investigation aimed to establish noninvasive methods for endocrine monitoring of estrous cycles and pregnancy in the Indian rhinoceros. Fecal samples were collected 1-3 times per week from nonpregnant and pregnant captive females (n = 7). Enzyme immunoassays for fecal progesterone, androgen, and estrogen metabolites, respectively, were tested for their ability to determine follicular and luteal phases and to characterize endocrine profiles during pregnancy. Antibodies used were raised against pregnanediol (20 alpha-OH-pregnanes), 20-oxo-pregnanes, epiandrosterone (17-oxo-androstanes), and total estrogens. Androgens and estrogens were found to be reliable indicators of the follicular phase, whereas 20 alpha-OH- and 20-oxo-pregnanes were reliable indicators of luteal function. Progesterone metabolites were also reliable indicators of pregnancy, whereas 17-oxo-androstanes and estrogens were basal throughout gestation. Estrous cycles were regular throughout the year, with an average cycle length of 43.4 +/- 1.5 (n = 27) days; the length of the follicular phase, as indicated by elevated estrogen levels, was 15.9 +/- 1.0 days, whereas the luteal phase, as indicated by elevated 20-oxo-pregnane levels, was 19.1 +/- 0.4 days. Fecal pregnane values were already increasing while follicular estrogen values were still decreasing. The length of the diestrus, indicated by basal steroid levels between declining 20-oxo-pregnanes and subsequently increasing estrogens, was 11.4 +/- 1.2 days. Pregnane levels increased from the 3rd month of gestation onward and levels exceeded luteal phase concentrations approximately 10 times by the 7th month of gestation onward. HPLC separation of immunoreactive fecal metabolites indicated the presence of estrone, estradiol-17beta, and several 17-oxo-androstanes, 20 alpha-OH-pregnanes, and 20-oxo-pregnanes. Concentrations of a peak with an elution profile similar to that of pregnanediol increased as pregnancy progressed. Postpartum fecal estrogen and 17-oxo-androstane concentrations in one animal indicated follicular development comparable to the follicular phase of the estrous cycle, but this was not followed by a subsequent luteal phase. In conclusion, estrous cycle and pregnancy in Indian rhinoceroses can be monitored using fecal steroid analysis. Pregnane metabolites were reliable indicators of the corpus luteum and pregnancy, whereas fecal 17-oxo-androstanes and estrogens were indicators of the follicular phase.

Faecal progesterone metabolite analysis for non-invasive monitoring of reproductive function in the white rhinoceros (Ceratotherium simum)

The two subspecies of white rhinoceros, southern (Ceratotherium simum simum) and northern (Ceratotherium simum cottoni), breed poorly in captivity, and estimates of oestrous cycle length vary considerably (range, 25-90 days). To characterise reproductive patterns, faecal samples were collected 2-3 times/week for up to 56 months from non-pregnant animals (n=21) of both subspecies. Immununoreactive pregnanes containing a 20-oxo-group (20-oxo-P) were analysed in a group-specific enzyme immunoassay using an antibody against 5alpha-pregnane-3beta-ol-20-one 3HS:BSA. Reproductive patterns were highly variable among and within individual animals. However, rhinoceroses could be classified into four major categories on the basis of oestrous cycle length and luteal phase 20-oxo-P concentrations: (1) regular oestrous cycles of 10 weeks duration and > 800 ng/g (n=2 animals); (2) oestrous cycles between 4-10 weeks and 250-750 ng/g (n=6); (3) no apparent cycle regularity, but luteal activity indicated by 20-oxo-P concentrations of 100-200 ng/g (n=6); (4) no apparent luteal activity as indicated by 20-oxo-P of < 100 ng/g (n=7). In two attempts to induce ovarian activity, chlormadinone acetate was fed daily to one animal for 35 and 45 days, respectively. Each treatment was followed by a subsequent hCG injection which resulted in luteal phases of 17 and 18 days, respectively, beginning about 10 days after hCG. Concentration of faecal 20-oxo-P in one pregnant animal during the 4th and 5th month of gestation were markedly higher than those observed during the luteal phase of the cycle. In conclusion, two thirds of white rhinoceroses in this study had erratic or missing luteal activity, whereas variable cycles of 4-10 weeks in length were evident in six females, and regular oestrous cycles of 10 weeks in length were found in two animals.

Growth responses and related biochemical and ultrastructural changes of the photosynthetic apparatus in birch (Betula pendula) saplings exposed to low concentrations of ozone

Saplings of ozone-sensitive and ozone-tolerant birch (Betula pendula Roth.), clones B and C, respectively, were exposed to ozone concentrations that were 1.7-fold higher than ambient for one growing season under open-field conditions. Ambient air was used as the control treatment. In the ozone-sensitive clone B, there was an initial stimulation of leaf area growth in response to the ozone treatment, but further ozone exposure caused reductions in leaf and stem biomass growth, Rubisco and chlorophyll a contents, net photosynthesis, water use efficiency and chloroplast size. It also caused an alteration in chloroplast shape and injury to thylakoid membranes. In the ozone-tolerant clone C, ozone fumigation did not affect growth rate, and there were no consistent changes in chlorophyll content, photosynthesis or water use efficiency. There were also fewer ultrastructural abnormalities in the chloroplasts of clone C than of clone B. Based on the observed biochemical, physiological and structural changes in chloroplasts of clone B in response to low concentrations of ozone, we conclude that the increasing concentration of tropospheric ozone represents a risk to natural birch populations.

Sex and season-related differences of basic haematological values in the mountain reedbuck (Reduncula fulvorufula)

1. Basic haematological values in the peripheral blood of four male and 13 female mountain reedbucks (Reduncula fulvorufula) have been repeatedly estimated. 2. Comparing these results for both sexes, we noted pronouncedly lower haematocrit values and haemoglobin contents in females (statistical significance less than or greater than 1%). In the white blood cells only an increased proportion of neutrophils in females was apparent. 3. We have been unable to find seasonal related differences in the red and white blood overall picture of the cells during the summer and winter seasons with the exception of raised red cell counts and increased proportion of monocytes in the winter. The presented findings are compared and discussed with those abstracted from the literature.

Basic haematological values in carnivores--I. The Canidae, the Hyaenidae and the Ursidae

Basic haematological values for 32 animals of four carnivore species are reported. In six adult wolves (Canis lupus) the mean values estimated for the erythrocyte count 7.48 X 10(12)/l, haematocrit 0.465/l, haemoglobin 172.0 g/l and leukocyte counts 7.33 X 10(9)/l are given. For five young wolves, these parameters were markedly decreased, only the white cell count was raised. In 14 hunting dogs (Lycaon pictus) the mean values estimated are: erythrocyte count 9.15 x 10(12)/l haematocrit 0.435/l, haemoglobin 179.2 g/l and leukocytes 12.95 X 10(9)/l. In six striped hyaenas (Hyaena hyaena) the mean estimated values are: erythrocyte count 8.11 X 10(12)/l, haemoatocrit 0.445/l, haemoglobin 178.0 g/l and leukocytes 13.95 X 10(9)/l. Only individual values for the reported parameters are given in the Asiatic black bear (Selenarctos thibetanus). All results are compared with values derived from the literature for animals under investigation and for the domestic dog (Canis familiaris).

Time-dependent influence of some sedating agents on basic haematological values in various artio- and perissodactylids

Basic haematological values in 32 animals of five species were estimated after administration of sedating agents. In all species under investigation, a time-dependent decrease of erythrocyte counts, haematocrit values and haemoglobin content was noted during the first 30 min after sedation, for the following 30 min the lowered values remained essentially without any change in zebras. Derived parameters, mean corpuscular haemoglobin, mean corpuscular Hb concentration and mean corpuscular volume did not change during the period of observation. Only insignificant changes in leukocyte count and in the proportion of lymphocytes and neutrophiles were registered. The shortest possible time between sedation and blood sampling is recommended to minimalize a distortion especially in the red blood picture.

Basic haematological values in the African buffalo (Syncerus caffer caffer) and in the red buffalo (Syncerus caffer nanus)

Basic haematological values in 13 African buffaloes (Syncerus caffer caffer), 11 cows and 2 bulls, and in 2 red buffaloes (Syncerus caffer nanus), 1 bull and 1 cow, are reported. In the African buffalo, the erythrocyte count--mean 9.76 X 10(12) 1(-1)--ranged from 6.72 to 12.42 X 10(12) 1(-1), the haematocrit values--mean 0.391--varied from 0.32 to 0.47 and the haemoglobin content--mean 148.17--was in the range from 122.1 to 172.5 g 1(-1). For the red buffalo only individual values are given. In the African buffaloes, the leukocyte counts--mean 7.39 X 10(9) 1(-1)--ranging from 5.1 to 12.4 X 10(9) 1(-1) were slightly increased compared with man. For the red buffalo only individual values are reported. These values are compared with data abstracted from the literature for related buffalo species. The age-dependent decrease of erythrocyte counts and the age-dependent rise of the eosinophile proportion in the differential count are discussed.

Basic haematological values in antelopes--III. The Reduncinae and the Antelopinae

Basic haematological values were measured in 50 individuals of five species falling under the subfamily Reduncinae, including the mountain reedbuck (Reduncula fulvorufula), the eastern waterback (Kobus ellipsiprymnus ellipsiprymnus), the defassa waterbuck (Kobus ellipsipyrmnus defassa), the lechwe waterbuck (Kobus leche) and the Lady Gray's waterbuck (Kobus megaceros) and in 45 animals of three species of the subfamily Antelopinae, including the springbok (Antidorcas marsupialis), the Grant's gazelle (Gazella Granti) and the dama gazelle (gazella dama). The highest mean erythrocyte counts were found in the male springbok: 11.72 X 10(12)/l, the lowest in the lechwe waterbuck: 8.39 X 10(12)/l, the mean haematocrit values varied from 0.538 in the lechwe waterbuck to 0.443 in the defassa waterbuck and the mean haemoglobin content ranged from 181.2 g/l in the male springok to 151.8 g/l in the defassa waterbuck. Leukocyte counts were mostly shown to be in the human range, in the subfamily Reduncinae at the lower limit; only in the mountain reedbuck decreased values of about 3.5 X 10(9)/l were demonstrated. These results are compared with information from the literature and with the normal human range.

Basic haematological values in antelopes--II. The Hippotraginae and the Tragelaphinae

Basic haematological values in 49 animals of five species of the subfamily Hippotraginae, namely the roan antelope Hippotragus equinus, sable antelope Hippotragus niger, adax antelope Addax nasomaculatus, gemsbok oryx Oryx gazella gazella and scimitar horned oryx Oryx damah and in 51 individuals of five species in the subfamily Tragelaphinae, including the bushbuck Tragelaphus scriptus, nyala Tragelaphus angasi, greater kudu Tragelaphus strepsiceros, cape eland Tautotragus oryx and bongo Bocercus euryceros are reported. The erythrocyte counts were in the range of 12.62 X 10(12)/l in the gemsbok oryx to 6.44 X 10(12)/l in the bongo, the haematocrit values varied from 0.488 in the nyala to 0.380 in the roan antelope and for the haemoglobin highest levels (164.0 g/l) were noted in the adax antelope, and the lowest (105.5 g/l) in the bongo. Leukocyte counts were found mostly in the normal human range and varied from 7.17 X 10(9)/l in the adax antelope to 4.05 X 10(9)/l in the nyala, only in the greater kudu decreased values of 3.02 X 10(9) were estimated. These results are compared with findings taken from the literature, and with the normal human range.

Basic haematological values in antelopes--IV. A comparison and concluding remarks

Comparison of mean erythrocyte counts, mean haematocrit values, mean haemoglobin content and mean corpuscular volume of the red cell is presented for 21 species of antelopes (four species being excluded because of the small number of animals investigated). A direct relationship of haematocrit values and haemoglobin content and an inverse relationship of red cell counts and mean corpuscular volume of the erythrocytes were noted. The significance of an increased total surface area for oxygen exchange is discussed and values obtained in the red blood picture are compared with those of domesticated animals (cattle, goat and sheep) taken from the literature. Mean leukocyte counts were found to be in the human range with the exception of two species, but significantly lower than in domesticated artiodactylids. Problems in assessing the general health, the age, the effect of diet and of environment in captivity are discussed. Problems of methodology, especially of blood sampling, are given comparing results in manually restrained and in sedated animals.