Oil reservoirs in stem, rhizome, and root of Solidago canadensis (Asteraceae, tribe Astereae)

The anatomy of internal secretory spaces in immature and mature aerial stems, rhizomes, and roots of common goldenrod, Solidago canadensis (Asteraceae, tribe Astereae), was studied from resin-embedded samples cut 1–2 μm thick. Oil-filled cavities of different lengths, each lined by a uniseriate epithelium, form in young stems and rhizomes. Epithelial cells enlarge and elongate, and some continue to divide mitotically. The cavities thereby expand and accommodate themselves to the growing stem and rhizome. Septa are sometimes forced open by this enlargement, which merges adjacent cavities. Oil reservoirs in roots are probably also cavities, but their lack of densely cytoplasmic epithelial cells prevented us from locating the end walls. Cavities in stem, root, and the cortex of rhizomes occur only as one median file located just outside of each phloem strand; in the pith of rhizomes, however, several files of cavities of larger diameter seem randomly distributed. This study extends our earlier findings that the oil reservoirs in leaves of this species are cavities; we have therefore verified that cavities, not ducts, permeate the goldenrod plant.     

DEVELOPMENT OF BICELLULAR FOLIAR SECRETORY CAVITIES IN WHITE SNAKEROOT,EUPATORIUM RUGOSUM (ASTERACEAE)

Bicellular secretory cavities in Eupatorium rugosum occur only in foliar mesophyll, distributed uniformly from leaf tip to base, with a mean density of 450 per mm². They are absent from petiole and all other vegetative and floral organs. Each cavity contains an oily droplet, which is surrounded by two cup-shaped cells. An initial cell divides into two equal cavity cells with their shared wall always perpendicular to the epidermis. After vacuoles form, each protoplast retracts from the other and deposits a new, callosic wall around the cavity, and a thicker callose deposit on the remaining shared walls outside of the cavity. The original shared wall remains intact across the cavity until maturity. It is pulled taut by cavity cell growth and restricts further expansion except in one paradermal direction. Later, this shared wall disappears from the cavity. An oily fluid of unknown composition is secreted into the enlarging cavity. Because bicellular cavities develop neither lysigenously nor in true schizogenous fashion, we propose the term “pseudoschizogeny” for this type of development. Unusual, or perhaps unique, features of this cavity: bicellular condition, protoplast retraction from the common shared wall, and deposition of a callose wall. Preliminary results of a survey of Eupatorium show that bicellular cavities are uncommon but widely distributed geographically.     

Formation of aerenchyma in roots of Zea mays in aerated solutions, and its relation to nutrient supply

The formation of lysigenous cavities (aerenchyma) in the root cortex of maize, Zea mays L. cv. Capella, under well-aerated conditions has been studied in relation to the composition of the nutrient solutions. Nitrogen, either supplied as nitrate or as ammonium, reduced the cavity formation by the roots. This reduction was most apparent at nitrate concentrations above 2 mM. Cavities were increasingly formed when the nitrate concentration was decreased and they reached their largest dimensions in roots growing in water. Thus, inadequate availability of nitrogen leads, under acrated conditions, to deterioration of cortex cells and cavity formation in the maize roots. It is suggested that cavity formation in these roots is connected with reduced nitrogen assimilation.     

When an epithelium ceases to exist – an ultrastructural study on the fate of the embryonic coelom in Epiperipatus biolleyi (Onychophora, Peripatidae)

It is an accepted fact that fusion between the coelomic cavities and the primary body cavity occurs during development in the Arthropoda. However, such a fusion is much disputed in the Onychophora. In order to clarify this subject, the fate of embryonic coelomic cavities has been studied in an onychophoran. Ultrastructural investigations in this paper provide evidence that embryonic coelomic cavities fuse with spaces of the primary body cavity in Epiperipatus biolleyi. During embryogenesis, the somatic and splanchnic portions of the mesoderm separate and the former coelomic linings are transformed into mesenchymatic tissue. The resulting body cavity therefore represents a mixture of primary and secondary (coelomic) body cavities, i.e. the ‘mixocoel’. The nephridial anlage is already present, when the ‘mixocoel’ is formed, although there is no trace of a sacculus yet. The lumen of the nephridial anlage, thus, communicates with the newly formed ‘mixocoel’. Accordingly, the lumen of the nephridial sacculus cannot be regarded as a kind of ‘persisting coelomic cavity’ in E. biolleyi. Our findings support the hypothesis that the ‘mixocoel’ was already present in the common stem species of the Onychophora and Euarthropoda.     

COMPARATIVE DEVELOPMENT OF SECRETORY CAVITIES IN THE TRIBES AMORPHEAE AND PSORALEEAE (LEGUMINOSAE: PAPILIONOIDEAE)

The tribes Amorpheae and Psoraleeae of the Leguminosae (Papilionoidae) share the characteristics of one-seeded fruits and gland-dotted foliage. Because of this, they traditionally have been considered closely related (either a single tribe or two closely related tribes). However, Barneby (1977) has suggested that the Amorpheae and Psoraleeae are not close but previously had been combined on the basis of a superficial resemblance. This paper describes the structure of the secretory cavities responsible for the gland dots. Approximately 50% of the species of each tribe were surveyed for cavity structure with leaflet clearings. Eight species were then chosen for developmental studies of their glands. Several distinct kinds of secretory cavities are present in these plants. Trabeculate cavities (found only in the Psoraleeae) are traversed by many elongated cells. This type of cavity and nontrabeculate cavities of the Psoraleeae initiate with localized dorsiventral elongation of protodermal cells to form a hemispherical protuberance on the leaf primordium surface. Development proceeds with separation of the cells of a protuberance along their lateral walls facing the protuberance center. As the leaf expands, the protuberance sinks until its apex is flush with the leaf surface. The result is a cavity lined by an epithelium of modified epidermal cells. Trabeculate cavities have more cells in the initial protodermal bump than nontrabeculate “epidermal” cavities, and the central cells of the protuberance are not involved in epithelium formation, but become separated from other cells on all lateral sides, transversing the cavity as trabeculae. Cavities of the Amorpheae are all nontrabeculate and subepidermal. They initiate with periclinal divisions of protodermal cells that result in two cell layers. The exterior layer differentiates into epidermis, while the interior layer divides to produce a small spherical group of cells (“epithelial initials”). Schizogeny occurs in the center of these cells to produce an epithelium-lined cavity. Previous studies of cavity development in the Amorpheae described lysigenous and schizo-lysigenous cavities for most species. These early reports are reviewed, and the possible role of preparation artifacts in producing images of lysigenous development in general is discussed.     

TEMPERATURE-INDUCED CAVITIES AND SPECIALIZED PARENCHYMA CELLS IN THE VASCULAR CYLINDER OF PEA ROOTS

Pea seeds (Pisum sativum L.) of six cultivars were planted in the field, in the greenhouse, or in growth chambers, in five different media, in light or dark, and at various temperatures (10–32 C). Under all conditions above 15 C the central portion of the vascular cylinder, in all cultivars except “Ageotropum,” tended to form cavities in almost every primary root examined. These cavities then became filled by the ingrowth of specialized parenchyma cells (SP cells). The formation of cavities and SP cells was temperature dependent since the roots grown below 15 C always formed central metaxylem tracheary elements (MTEs), without cavities and SP cells. Cavities and SP cells did not form over the entire root length. When the roots were longer than 3 cm, they started to form cavities and SP cells and continued for an additional 10–30 cm. After that, late MTEs formed in the central vascular cylinder, and no cavities and SP cells occurred regardless of temperature. Within an individual root grown above 15 C, cavities and SP cells tended to form during periods of fast growth, while during periods of slow growth large central MTEs formed instead.     

The Protonephridia of the Arctic Kinorhynch Echinoderes aquilonius (Cyclorhagida,Echinoderidae)

The cyclorhagid kinorhynch Echinoderes aquilonius Higgins & Kristensen, 1988 possesses a single pair of protonephridia located in segments 10 and 11. The protonephridia consist of: (1) three terminal cells T-1, T-2. T-3, each with two cilia; (2) a single non-ciliated canal cell; (3) a nephridiopore cell with many microvilli and a cuticular sieve plate. The protonephridia of Echinoderes are presumed to develop from the ectoderm near the area of the sieve plate on the eleventh segment, and are suspended in the dorso-lateral pseudocoelomic cavity where they are surrounded by a basal lamina. One of the terminal cells (T-1) secondarily penetrates the basal lamina of the tenth segment and a part of the cell attaches to the cuticle. The kinorhynch protonephridia are compared with the excretory organs of other Bilateria. expecially the ‘aschelminths’, and apomorphic characters of the kinorhynch protonephridia are defined.     

Regeneration of tissue following cavity formation in the vascular cylinders of Pisum sativum (Fabaceae) primary roots

The reorganization of vascular cylinders of pea (Pisum sativum, cv. Alaska) primary roots following the formation of vascular cavities was examined by light and electron microscopy. Cavities usually began forming ~20 mm from the root tip and were continuous to ~90 mm from the tips in roots 150 mm long, where they began filling with specialized parenchyma cells (SP cells). SP cells were usually produced by enlargement of parenchymous cells of the primary xylem at cavity margins. Depending on the extent and shape of the cavity, they were also sometimes produced by primary phloem parenchyma and early derivatives of the vascular cambium. Enlargement and some divisions of SP cells continued until a cavity was completely filled by them. SP cells proceeded through a series of cytoplasmic changes as they developed. First the cytoplasmic layer became thicker and more electron dense than surrounding cells. As SP cells enlarged there was an increase in vesicular traffic and the cytoplasm became less electron dense. Ultimately the cytoplasm thinned further, organelles degenerated, and the tonoplast sometimes broke down. SP cells did not form secondary walls. X-ray microanalysis revealed that SP cells accumulated potassium and rubidium to the same degree as cortical and xylem parenchyma cells and to a greater degree than immature secondary and late-maturing tracheary elements.     

Sperm storage by spermatodoses in the spermatheca of Trioza alacris (Flor, 1861) hemiptera,psylloidea, triozidae: A structural and ultrastructural study

Female insects generally store sperm received during mating in specific organs of their reproductive tract, i.e., the spermathecae, which keep the sperm alive for a long time until fertilization occurs. We investigated spermatheca morphology and ultrastructure in the psylloidean insect Trioza alacris (Flor, 1861 ) in which spheroidal sperm packets that we refer to as ‘spermatodoses’ are found after mating. The ectoderm‐derived epithelium of the sac‐shaped spermatheca that has a proximal neck, consists of large secretory and flat cuticle‐forming cells. Secretory cells are characterized by a wide extracellular cavity, bordered by microvilli, in which electron‐dense secretion accumulates before discharge into the spermathecal lumen. The cuticle‐forming cells produce the cuticular intima of the organ and a peculiar specialized apical structure, through which secretion flows into the lumen. At mating, the male transfers bundles of sperm cells embedded in seminal fluid into the spermathecal neck. Sperm cells proceed towards the spermathecal sac lumen, where they are progressively compacted and surrounded with an envelope that also encloses secretions of both male and female origin. We describe the formation of these sperm containing structures and document the contribution of the female secretion to spermatodose or female‐determined spermatophore construction. We also discuss the choice of the term ‘spermatodose’ for T. alacris and suggest it be used to refer to sperm masses constructed in the female reproductive organs, at least when they involve the contribution of female secretion. © 2011 Wiley Periodicals, Inc.     

Mapping of protein surface cavities and prediction of enzyme class by a self-organizing neural network

An automated computer-based method for mapping of protein surface cavities was developed and applied to a set of 176 metalloproteinases containing zinc cations in their active sites. With very few exceptions, the cavity search routine detected the active site among the five largest cavities and produced reasonable active site surfaces. Cavities were described by means of solvent-accessible surface patches. For a given protein, these patches were calculated in three steps: (i) definition of cavity atoms forming surface cavities by a grid-based technique; (ii) generation of solvent accessible surfaces; (iii) assignment of an accessibility value and a generalized atom type to each surface point. Topological correlation vectors were generated from the set of surface points forming the cavities, and projected onto the plane by a self-organizing network. The resulting map of 865 enzyme cavities displays clusters of active sites that are clearly separated from the other cavities. It is demonstrated that both fully automated recognition of active sites, and prediction of enzyme class can be performed for novel protein structures at high accuracy.     

Dark tree cavities – a challenge for hole nesting birds?

Holes provide the safest nest sites for birds, but they are an underutilized resource; in natural forests there are usually more holes than birds that could use them. Some bird species could be prevented from nesting in holes because of their inability to operate in the low light conditions which occur in cavities. As no visual system can operate in complete darkness some nest cavities could be too dark to be useable even by hole‐nesters. Thus, the light conditions within tree cavities could constrain both the evolution of the hole nesting habit, and the nest site choice of the hole‐nesting birds. These ideas cannot be tested because little is known about the light conditions in cavities. We took an opportunity provided by ongoing studies of marsh tits Poecile palustris and great tits Parus major breeding in a primeval forest (Bia?owie?a National Park, Poland) to measure illumination inside their nest cavities. We measured illuminance in cavities at daybreak, which is just after the parents commenced feeding nestlings. Only ca 1% of incoming light reached the level of the nest. Illuminance at nests of both species (median = 0.1–0.2 lx) fell within mesopic‐scotopic range, where colour vision is impaired. Measurements in model cavities showed strong declines in illumination with distance from the entrance, with light levels typically as low as 0.01 lx at 40 cm from the cavity entrance. Thus cavities can be very dark, often too dark for the use of colour vision, and we suggest that ‘lighting’ requirements can affect the adoption of specific nest sites by hole nesting birds. We discuss implications of the findings for understanding the adaptations for hole‐breeding in birds.     

A review about nothing: Are apolar cavities in proteins really empty?

Cavities within proteins that are strictly apolar typically appear to be empty. It has been suggested, however, that water molecules may be present within such cavities but are too disordered to be seen in conventional crystallographic analyses. In contrast, it is argued here that solvent mobility will be limited by the size of the cavity and for this reason high‐occupancy solvent in cavities of typical volume should be readily detectable using X‐ray crystallography. Recent experimental studies of cavity hydration are reviewed. Such studies are consistent with theoretical predictions that it is energetically unfavorable to have a single water molecule in an apolar cavity. As apolar cavities become larger, a point is reached where it is favorable to have the cavity occupied by a cluster of mutually H‐bonded water molecules. The exact size of such a cavity in a protein is yet to be verified.     

Foliar oil reservoir anatomy and distribution in Solidago canadensis (Asteraceae, tribe Astereae)

In leaves of goldenrod, Solidago canadensis (Asteraceae, tribe Astereae), numerous internal oil reservoirs with a uniseriate epithelium occur as a single file above or below veins or as isolated cavities in the mesophyll. Reservoirs are abaxial to major veins (vein orders 1–3), either above, below, or superimposed in intermediate 4th order veins, but strictly adaxial to 5th and 6th order minor veins. Reservoirs are initiated as discrete cavities, but those below 1st and 2nd order veins are in a single crowded file, each separated only by epithelial cells. Elongation of these cavities, accompanied by stretching and separation of septa, gives a false impression at maturity of an indefinitely long duct instead of a series of tubular cavities. Reservoirs of vein orders 3–6 are mostly more widely separated and less subject to elongation, thus they are shorter and remain discrete at maturity. The overall foliar pattern is one of successively shorter reservoirs, a sequence that is in concert with the successively narrower and progressively less elongated vein orders. The shift from abaxial to adaxial reservoirs in minor veins may be related to different phloem functions: sugar transport in major veins and photosynthate assimilation in minor veins.     

Projected Availability of Natural Cavities for Wood Ducks in Southern Illinois

Abstract: Wood ducks (Aix sponsa) and other species use tree cavities in forested wetlands and adjacent upland forests for nest sites and cover. The availability of tree cavities suitable for nesting is important to the population dynamics of hole-nesting species, but there is little quantitative information on how forest succession and maturation affect densities of suitable nest sites in eastern deciduous forests. Several studies have measured availability of tree cavities for nesting wood ducks, but data on cavity formation and persistence rates are needed to model changes in cavity abundance. We measured abundance and persistence of tree cavities suitable for nesting wood ducks in southern Illinois, USA, during 1993-2002. We simulated changes in abundance of nest cavities in the Mississippi River floodplain and adjacent upland forests using estimates of tree cavity densities by tree-diameter size classes and 10-year cavity persistence rates by tree species. Cavities were disproportionately common in the largest size classes, but tree species varied in their propensity to form cavities. Beech (Fagus grandifolia; 0.41 cavities/tree) and sycamore (Plantanus occidentalis; 0.50 cavities/tree) were prolific cavity producers, whereas a small proportion (0.05 cavities/tree) of cottonwoods (Populus deltoides) contained cavities. Kaplan-Meier estimates of annual and 10-year cavity persistence averaged 0.95 and 0.64, respectively. Cavity persistence also differed among species (P = 0.02): cottonwoods had the lowest (0.54) and sycamores had the highest (0.89) 10-year tree cavity persistence rates. Tree fall (50.0%), cavity floor deterioration (37.5%), and narrowing of the cavity entrance (12.5%) were the most prevalent causes of tree cavity loss. Forest stand projections indicated that cavity abundance will increase up to 34% over recent levels during the first 10 years and by 44% after 50 years. Most of this increase will be contributed by tree species that are not commonly used by wood ducks, but cavities will increase in oaks (Quercus spp.) and beeches as the forest matures into cavity-bearing size classes. Sycamores will steadily contribute cavities, but cottonwood is predicted to provide fewer cavities due to low survival of cavity-bearing size classes. Our results suggest that availability of nest and den sites for cavity-dependent wildlife will increase as eastern deciduous forests mature over the next half century. Cost-effectiveness of artificial nest box programs should be reevaluated in light of projected changes in tree cavity availability as deciduous forests mature in the eastern United States.     

Structure and development of the secretory cavities of Myrtus communis leaves

The structure and development of Myrtus communis L. secretory cavities has been studied in young and expanded leaves, using light and scanning electron microscope. Secretory cavities are continuously formed during leaf development, but in mature leaves the rhythm of their appearance shows steep decrease. Each secretory cavity is developed from a single epidermal cell, which undergoes a periclinal division followed by anticlinal and several oblique cell divisions. The lumen of the secretory cavity is initiated by cell wall separation, i.e., schizogenously. The secretory cells line the cavity, where the secreted material is collected. Secretory cavities are covered by modified epidermal cells, which do not seem to form any special aperture. Essential oils seem to be discharged after mechanical treatment of the leaf.     

The potential availability of roosting sites for lesser short‐tailed bats (Mystacina tuberculata) on Kapiti Island,New Zealand: Implications for a translocation

Abstract

Lesser short‐tailed bats (Mystacina tuberculata) have recently been translocated to Kapiti Island in an attempt to form a new population of this threatened species. However, the island's vegetation is regenerating, and there was doubt that the forests provided enough large trees with cavities for bats to roost in. This study measured the availability of tree‐trunk cavities of the right size for potential roost sites on Kapiti Island, and assessed if habitat restoration would be required to increase the translocation's chance of success. first, trees with cavities accessible to us were sampled in six of Kapiti Island's forest types. Size variables known to affect roost site selection by lesser short‐tailed bats at the tree and cavity level were measured. Trees were classified as containing cavities that could potentially provide suitable roosts if their values for all variables measured fell within the range of roosts used by lesser short‐tailed bats in natural populations. Roosts were classified as suitably sized for solitary bats or for colonies, using measurements from both types of roosts in natural populations. Second, the density of these potential roost cavities was calculated. Cavities of a size potentially suitable for colonies were found in four of the six forest types at densities ranging from 3.2 ± 3.2 Se to 52.4 ± 14.0 trees per ha. density of potential solitary roosts was much higher. Not all potential cavities will be suitable because they may be damp, poorly insulated, or have an unsuitable microclimate. Nevertheless, our estimates indicated that the two most extensive forest types each contained thousands of potential cavities of a size suitable for colonies of lesser short‐tailed bats. In addition, there were tens of thousands of cavities large enough to shelter solitary bats. Roost habitat restoration appears unnecessary to assist translocated Mystacina tuberculata on Kapiti Island.     

Details of cavities used by Syrian Woodpeckers Dendrocopos syriacus in Hungary

ABSTRACT

Eighty-two nest and roosting cavities of Syrian Woodpeckers Dendrocopos syriacus were documented over a period of 25 years (1994–2018). Fourteen different tree species were used, the majority being non-native in Hungary. Cavities were found in both main trunks and in larger limbs. The median cavity height was 3.0 m and ranged from 1 to 7 m. The cavity entrance orientation was non-random with a preference for a south-southeast orientation.     

SOUND PRODUCTION IN MUTILLID WASPS (MUTILLIDAE,HYMENOPTERA)

ABSTRACT

The stridulatory organs of male and female Mutillid wasps are similar and occur between their 3rd and 4th abdominal tergites. The three investigated species, Smicromyrme rufipes, Dasylabris kozlovi and Mutilla marginata, possess files with different ‘ripple’ distances that are species specific (2.5 to 5.4 micrometres). The sonagram of the distress calls from female M. marginata shows the ripple frequency with low amplitude rising in the first 20 milliseconds from 1.2 to 1.5 kHz and then falling back in the following 20 milliseconds. The main sound energy occurs in the 2nd and 3rd harmonics.     

FLORAL ANATOMY OF KRAMERIA LANCEOLATA

The anatomy of each of the series of floral organs of Krameria lanceolata was examined. The sepals are characterized by three main veins each, an undifferentiated mesophyll, and stomata on the upper epidermis. The fleshy petals are distinguished by their numerous veins as well as by palisade-like epidermal cells on the outer surface. The three partially united petals have each a single vein and long, narrow epidermal cells similar to those on other floral organs. The stamens are united at their bases and bear tetra-sporangiate, conical anthers. The gynoecium includes a sterile and a fertile carpel. In the receptacle the veins to the sepals and petals are separated by a wide gap; those to the petals and stamens, by a narrow gap. Anatomical characteristics of the flower dissociate Krameriaceae from the legumes with which they have frequently been thought to be allied.