Operculum development inEucalyptus clöeziana andEucalyptus informal subg.Monocalyptus (Myrtaceae)

Flowers ofEucalyptus clöeziana have two clearly distinct perianth whorls. The small free parts of the outer (calycine) whorl cease growth early and are lost from the flower; the parts of the inner (corolline) whorl become continuous laterally by confluence of growth centres and form an operculum in the mature flower. The stamens are inserted on a circumfloral buttress (staminophore) that is homologous to the adaxial corolline component inAngophora and the bloodwood andEudesmia eucalypts. Flowers ofMonocalyptus have only one perianth whorl, which is opercular. The stamens are similarly inserted on a circumfloral buttress. Developmental study does not provide conclusive evidence for either a calycine or corolline determination of theMonocalyptus operculum, but comparison with other eucalypt groups, includingE. clöeziana (the sister taxon), predicts an essentially corolline composition.     

Rectal gland morphology of freshwater and seawater acclimated bull sharks Carcharhinus leucas

To compare rectal gland morphology of bull sharks Carcharhinus leucas , animals captured in the freshwater reaches of the Brisbane River, Australia, were acclimated to sea water over 17 days with 1 week in the final salinity. A control group was left in fresh water for 17 days. Animals in fresh water and sea water were strongly hyper- and hypo-ionic with respect to plasma Na⁺ and Cl^–, respectively. This difference necessitates NaCl secretion by the rectal gland in sea water and conservation of NaCl in fresh water. Structural differences in the rectal gland of freshwater and seawater acclimated bull sharks were limited. There was no difference in rectal gland cross-sectional area, lumen area, rectal gland vein area, number of secretory tubules or secretory cells per secretory tubule in freshwater and seawater acclimated animals. At a cellular level, there was no difference between the degree of basolateral and lateral folding, number of mitochondria or number of desmosomes per tight junction. Tight junction width was significantly greater in seawater acclimated animals. The number of red blood cells in the interstitial tissue was also significantly higher in seawater acclimated animals, possibly as a result of increased blood perfusion of the secretory epithelia. The lack of major structural changes in the rectal glands of bull sharks acclimated to fresh water and sea water most likely represents the salinity gradient in the Brisbane River where animals are found throughout the river and can experience large fluctuations in salinity over short distances. Differences in rectal gland morphology of bull sharks in fresh water and sea water are discussed in terms of their relevance to osmoregulation in elasmobranchs.     

The first vespiform tineid moth (Lepidoptera: Tineidae)

Abstract Vespitinea gurkharum gen. et sp.n. is described from specimens reared from a bracket-fungus ( Ganoderma - Polyporaceae) from lowland rain-forest in Brunei. This striking wasp-like moth is suggested to be a Batesian mimic of species of Vespidae and Pompilidae (Hymenoptera) and the first example of this mimicry type recorded from the Tineoidea. Abdominal, eye and wing-coupling modifications suggest that it is diurnal and a behavioural mimic. The systematic position of Vespitinea is discussed with reference to biology and adult and larval morphology.     

Functional morphology of the spiracles in two species of Argasidae (Metastigmata: Acarina), with particular reference to responses to desiccation

Spiracle morphology of Argas persicus (Oken) and Omithodorus acinus Whittick is described and the differences between the two species are related to biological factors. Argasid and ixodid spiracle structures and functions are compared.     

Concordant clines and significant correlation between floral and pollen characters in Asarum heterotropoides var. heterotropoides (Aristolochiaceae)

To examine geographic differentiation in Asarum heterotropoides var. heterotropoides in Hokkaido Is. in the northern Japan, in which two putative cryptic species have been suspected to exist, extensive and detailed morphological research on 794 individuals from 44 populations throughout Hokkaido Is. was performed. Among the characters examined, the angle between and tip shape of the calyx lobes and the supratecta of the pollen grains were significantly correlated and were found in similar geographic clines. Among them, the pollen showed two discrete states in almost distinct distribution. Multidimensional scaling analysis showed that individuals within each of the two pollen types had different trends in flower characters. Consequently, we assumed a cline from south to north on Hokkaido Is. For the causes of the cline, the two hypotheses were proposed, primary geographic differentiation or extensive introgressive hybridization between two distinct geographical species existing in the past.     

Cell division study in ‘pollen mother cells’ and ‘pollen grains’ of in vivo and ex vitro plants in Drimiopsis botryoides

The various normal and abnormal stages of meiosis and pollen mitosis of Drimiopsis botryoides are described, and a comparison between naturally propagated in vivo and tissue culture derived ex vitro plants in respect to their cytological behaviour presented. We also describe the floral morphology and investigate the relationship between the floral developmental stages and the progression of microgametogenesis. In total, 33 bivalents are observed in diakinesis, which indicate the diploid number 2n = 66 and this number is cross-checked by a haploid set of n = 33 chromosomes in pollen mitosis. Only 6.8% and 4.9% meiotic abnormalities were recorded on in vivo and ex vitro plants, respectively, which led to the formation of non-viable pollen. Finally, the microspores have to develop into tri-cellular male gametophyte. Only 0.2% pollen grains are found with a micro-nucleus. Though the higher pollen viability was recorded on both in vivo (89.3 ± 4.1%) and ex vitro (92.1 ± 4.6%) plants, but surprisingly the pollen germination rate is extremely low with 13.6 ± 1.74% and 21.3 ± 1.55%, respectively. The present study obviously enriches the cytological database of D. botryoides and may help future research on androgenesis and genetic improvement.     

Choice of hydrogen uptake (Hup) status in legume‐rhizobia symbioses

The H₂ is an obligate by-product of N-fixation. Recycling of H₂ through uptake hydrogenase (Hup) inside the root nodules of leguminous plants is often considered an advantage for plants. However, many of the rhizobium-legume symbioses found in nature, especially those used in agriculture are shown to be Hup⁻, with the plants releasing H₂ produced by nitrogenase activity from root nodules into the surrounding rhizosphere. Recent studies have suggested that, H₂ induces plant-growth-promoting rhizobacteria, which may explain the widespread of Hup⁻ symbioses in spite of the low energy efficiency of such associations. Wild legumes grown in Nova Scotia, Canada, were surveyed to determine if any plant-growth characteristics could give an indication of Hup choice in leguminous plants. Out of the plants sampled, two legumes, Securigera varia and Vicia cracca, showed Hup⁺ associations. Securigera varia exhibited robust root structure as compared with the other plants surveyed. Data from the literature and the results from this study suggested that plants with established root systems are more likely to form the energy-efficient Hup⁺ symbiotic relationships with rhizobia. Conversely, Hup⁻ associations could be beneficial to leguminous plants due to H₂-oxidizing plant-growth-promoting rhizobacteria that allow plants to compete successfully, early in the growing season. However, some nodules from V. cracca tested Hup⁺, while others were Hup⁻. This was similar to that observed in Glycine max and Pisum sativum, giving reason to believe that Hup choice might be affected by various internal and environmental factors.     

Functional Diversity of Culturable Bacterial Communities in the Rhizosphere in Relation to Fine-root and Soil Parameters in Alder Stands on Forest, Abandoned Agricultural, and Oil-shale Mining Areas

Grey alder (Alnus incana) and black alder (Alnus glutinosa) stands on forest land, abandoned agricultural, and reclaimed oil-shale mining areas were investigated with the aim of analysing the functional diversity and activity of microbial communities in the soil–root interface and in the bulk soil in relation to fine-root parameters, alder species, and soil type. Biolog Ecoplates were used to determine community-level physiological profiles (CLPP) of culturable bacteria in soil–root interface and bulk soil samples. CLPP were summarized as AWCD (average well color development, OD 48 h⁻¹) and by Shannon diversity index, which varied between 4.3 and 4.6 for soil–root interface. The soil–root interface/bulk soil ratio of AWCD was estimated. Substrate-induced respiration (SIR) and basal respiration (BAS) of bulk soil samples were measured and metabolic quotient (Q = BAS/SIR) was calculated. SIR and Q varied from 0.24 to 2.89 mg C g⁻¹ and from 0.12 to 0.51, respectively. Short-root morphological studies were carried out by WinRHIZO^TM Pro 2003b; mean specific root area (SRA) varied for grey alder and black alder from 69 to 103 and from 54 to 155 m² kg⁻¹, respectively. The greatest differences between AWCD values of culturable bacterial communities in soil–root interface and bulk soil were found for the young alder stands on oil-shale mining spoil and on abandoned agricultural land. Soil–root interface/bulk soil AWCD ratio, ratio for Shannon diversity indices, and SRA were positively correlated. Foliar assimilation efficiency (FOE) was negatively correlated with soil–root interface/bulk soil AWCD ratio. The impact of soil and alder species on short-root morphology was significant; short-root tip volume and mass were greater for black alder than grey alder. For the investigated microbiological characteristics, no alder-species-related differences were revealed.