Temporal dynamics of tuber formation and related processes in a crossing population of potato (Solanum tuberosum)

The chronological relationships between stolon formation, stolon tip swelling, tuber initiation, flowering, senescence, growth and resorption of tubers were studied under field conditions in a diploid population of potato with 238 genotypes, the parental clones and seven tetraploid cultivars. Timing of tuber initiation was not closely related to the timing of stolon formation, flowering and duration of the plant cycle. Tuber initiation very often preceded stolon branching. The number and size distribution of tubers were largely influenced by the degree of stolon branching, the length of the stolon swelling period and tuber resorption. The peak production of stolons and swollen stolon tips largely took place within the flowering period, although in most genotypes, some stolon tip swelling took place until the end of the plant cycle. More information on the general temporal relationships between events related to tuber formation and plant development will contribute to a better understanding of the physiological and genetic basis of the processes leading to the production of harvestable tubers.     

Symbiosis in the Larger Foraminiferan Sorites marginalis (with Notes on Archaias spp.)

SYNOPSIS. It was demonstrated with the aid of light and electron microscope studies that Sorites marginalis (Lamarck) harbors zooxanthellae. The hosts were scraped from Thalassia testudinum Konig growing in Key Largo Sound (Florida, U.S.A.) and immediately preserved in appropriate fixatives. Zooxanthellae were distributed unevenly throughout all the chamberlets; only a few symbiotes were found in the embryonic chambers and the inner or outer chambers, but the intermediate chambers were packed with symbiotes. The outer chambers contained many food vacuoles in addition to symbiotes. Some zooxanthellae might have been in the process of degeneration or digestion. The symbiotes were found to have a typical dinoflagellate nucleus, a single large lobate cortical chloroplast with one stalked pyrenoid, an accumulation body, and many starch granules. The nonmotile stage of the zooxanthella was similar, but perhaps not identical, to Symbiodinium microadriaticum Freudenthal from various hosts.
The foraminiferan host is heterokaryotic with hundreds of generative (small) nuclei and scores of vegetative (large) nuclei. Most of the generative nuclei were found in the embryonic apparatus and the inner chambers. Most of the vegetative nuclei were found in the inner and outer chambers.     

Le genre Murciella (Foraminifère, Rhapydionininae), dans le Crétacé supérieur de Grèce (zone de Gavrovo-Tripolitza)

Several new species are described, of which theendoskeletal features present strong similarities with YaberinellaVaughan. Each chamber consists of: 1) a single peripheral layer of tubular «primary chamberlets perpendicular to the septa they join, 2) concentric inner layers of tubular «secondary chamberlets oriented obliquely to the preceding, each layer inclined in the contrary sense to its inner and outer neighbour, and the inclination being symmetrical with respect to any radial plane. Thus the secondary chamberlets form two helices, each with the same axis, which is also the axis of the chamber and the axis of growth: this is called «helicoidal structure. Lateral connections exists between the tubes of different layers («stolons).The chamber arrangement, and above all the presence of a preseptal space equipped with buttresses exclude the new species from Yaberinella and permits their assignment to the sub-family Rhapydionininae, more precisely to the genus MurciellaFourcade, of which several known sections (particularly the holotype of the type-species) seem to show the same organisation.The mode of coiling shown by some of the new forms, together with the lateral connection between chamberlets (the function of which might be the same as that of the preseptal space) permit the advocation of a development from Murciella (Tethysian, Upper Cretaceous) to Yaberinella (central American, Eocene).     

Involvement of Endogenous Gibberellins in the Chilling Requirements of Strawberry (Fragariaxananassa Duch.)

Plants of Fragaria ananassa Duch. cvs Tioga and Fresno werechilled in a cold store at—1°C for 2–8 months,after which they were transferred to short-day (SD) and long-day(LD)) growth chambers. Chilling promoted subsequent vegetative development, as expressedthrough leaf area, petiole length and stolon production, butinhibited the formation of inflorescences. Leaf area and petiolelength responses appeared to be almost saturated by 2 months'chilling. The increase in stolon production and the reductionin inflorescence formation came into full expression with longerperiods of chilling. Application of gibberellin A₃ (GA₃ to plants pre-chilied for2 months had little effect on leaf area or petiole length butpromoted stolon production and retarded the formation of inflorescences.AMO-1618 applied to plants pre-chilled for 4 months antagonizedthe chilling responses. The level of diffusible gibberellin-like substances from crownapices remained low during most of the chilling period but increasedmarkedly after 6–8 months of chilling, when plants approachedspontaneous sprouting in the cold store. Plants pre-chilledfor 2 months had low levels of gibberellin-like substances whichincreased several fold upon transfer to the growth chambers.This increase was somewhat delayed in plants treated with AMO-1618. The role of gibberellins in the responses of strawberry plantsto chilling is discussed.     

<Emphasis Type="Italic">Cyclopertorbitolites</Emphasis>, a new soritid (Foraminifera) from the Lower Eocene of the Eskişehir and Kastamonu regions (Turkey)

The Lower Eocene sediments in the southwestern Seyitgazi (Eskişehir) region include shallow-water rhythmic deposition of claystones, limestones, clayey limestones, and sandy limestones. The Lower Eocene unit in the northwestern Tosya (Kastamonu) region is composed of shallow-water limestones. Both units contain a new soritid foraminiferal genus, Cyclopertorbitolites (with the type species Cyclopertorbitolites tokerae sp. nov.). Cyclopertorbitolites tokerae gen. et sp. nov. is described in the Middle Ilerdian-Lower Cuisian sediments of Seyitgazi and in the Middle Ilerdian limestones of Tosya in this study. It is characterized by the presence of regular annular chambers with rectangular or subrectangular chamberlets at the juvenile stage and a porcellaneous lamina on either side of the test.     

Studies on hydroid differentiation. VII. The hydrozoan stolon

The stolon of the colonial marine hydroid Podocoryne carnea differentiates sequentially as a function of age, forming four distinguishable regions characterized by epidermal cell differentiation: The Tip, New Stolon, Cnidogenic Masses, Old Stolon. Radioautographs of sections of colonies exposed to tritiated thymidine show that although cells of the epidermis and gastrodermis of the stolon incorporate the nucleoside into acid stable polynucleotide, cells of the stolon tips do not. Stolon extension is not, therefore, the result of a localized meristem-like growth zone. Stolon branching and new polyp formation are, similarly, not signaled by increased thymidine incorporation. The initial event heralding these morphogenetic activities appears to be the reorientation of epidermal cells along a new axis, and the acquisition of perisarc dissolving ability. This evidence is contraindicative of direct dependence of colony form on colony growth. The larger part of stolon epidermal cells are organized into cnidogenic masses where cnidocytes and possibly other amoebocytic cells are produced. Although no mitotic figures have been observed in gastroderm cells of the stolon, thymidine incorporation in this tissue occurs with the same frequency as it does in epidermis. Considerable numbers of gastroderm cells can be found in the gastric cavity. Frequently these and gastroderm cells in the stolon and polyps contain more than one nucleus.     

慈姑匍匐茎的起源和球茎的膨大研究

匍匐茎的发生一般见于主茎倒二或倒三叶原基的叶腋部位。在匍匐茎发生区域的主茎一侧,匍匐茎原始细胞的基部形成壳状区;壳状区的形成对匍匐茎原基的外凸起一定作用。匍匐茎无居间分生组织;它的伸长依靠顶端分生组织细胞的横向分裂,使轴向细胞数目增多,并使细胞的轴向延伸。球茎的膨大是通过匍匐茎第8—10节基本分生组织的细胞有丝分裂,增加细胞数目,然后细胞体积的扩大来实现的。球茎中的淀粉一般为单粒淀粉;匍匐茎中的淀粉由单粒和复合两种淀粉粒组成。     

Cell Proliferation in the Terminal Regions of the Internodes and Stolons of the Colonial Hydroid Campanularia flexuosa

Pattern formation and cell proliferation have been believedto have a causative relationship in the colonial hydroids. Herelinear stolon growth was assumed to be dependent on polarizedcell proliferation restricted to the extreme end of the stolon.The popularity of the concept that pattern formation was a resultof restricted meristematic cell proliferation was based on acorrespondence between the observed growth patterns and theconcept. Nevertheless, there is little direct knowledge of cellproliferation in the stolons of hydroids. The primary objective of this investigation was to determinethe sites of cell proliferation in the terminal growth zonesof the colonial hydroid Campanularia flexuosa in order to evaluatethis concept. The results give evidence that cell proliferationis more or less uniformly distributed throughout the terminalstolon and the internodes of upright stems, and not restrictedto the tips of the stolons and internodes as has been previouslypostulated. Cell proliferation occurs in both the epidermis and gastrodermisof the stolon in a ratio of 3 to 2. The formation of a new uprightis accompanied by increased cell proliferation localized atthe site of initiation. The uniform distribution of cell proliferation in the stolonsupports the hypothesis that growth is via intercalary cellproliferation, which was proposed eailier on the basis of evidenceobtained from the displacement of vital stained bands of tissuein the stolon. Stolon growth via intercalary cell proliferation requires areconsideration of the factors which control morphogenesis.Wolpert has pointed out the importance of determining the mitoticpattern in a developing system before an understanding of positionalinformation within the system may be studied. Thus, informationfor greater insight into the study of positional informationin a developing hydroid has been obtained.     

New Paleocene large cassiduline foraminifera (Cassidinidae fam. nov., Miscellanacea) from Egypt and its phylogeny

Larger foraminifera of the Late Paleocene–Early Eocene lower slope to toe-of-slope deposits of the southern Galala, Egypt, are described. Sulcocassidina nakkadyi n. gen. et sp. (base) and Vacuolicassidella dakhlensis n. gen. et sp. (top) represent a phylogenetic line related to the family Cassidinidae (new family), superfamily Miscellanacea (new superfamily) in the latest Paleocene (shallow benthic zone 4) of the southern Galala, Egypt. In addition, Oscucassidella cassis n. gen. et sp., Pellatispiroides youssefi n. gen. et sp. and Chordcassidella ainshamsiana n. gen. et sp. are described and illustrated. Genus: Pomerolina n. gen. (Type species: Alveolina meandrina Carter, 1861, is newly erected and it belongs to Cassidinidae. In this family, the chambers are initially arranged streptospirally, whereas in later stages they are planispirally enrolled. Lateral chamberlets (retral process) are separated from the laminae by a passage and a marginal crest is added during growth.     

短穗兔耳草基株大小对其克隆生长特征的影响

对采自青藏高原5个不同海拔高度上的短穗兔儿草基株干重与匍匐茎数量、单位长度匍匐茎干重和无性系分株干重之间的相关性,以及匍匐茎与无性系分株总干重与基株干重的比值进行了分析.结果表明,除人为干扰比较严重的生境外,基株大小与匍匐茎数量、单位长度匍匐茎干重之间存在极显著的正线形相关(P<0.01),基株大小对分株的影响可能与匍匐茎数量有关;匍匐茎与分株总干重与基株干重的比值在海拔最高和最低两个样地中最大.短穗兔儿草基株干重对克隆生长有明显的影响,但在不同海拔高度影响作用的大小和方式表现出一定的差异.     

海滨沙地单叶蔓荆匍匐茎对沙埋适应的生长对策

单叶蔓荆(Vitex trifolia var.simplicifoli)是一种耐盐、耐旱固沙地被植物。依据海滨沙地自然沙埋特点对单叶蔓荆匍匐茎进行了不同厚度(半埋和全埋)和不同长度交叉沙埋处理,研究探讨了单叶蔓荆沙埋适应生长对策,为其开发利用、科学管理和海滨环境修复提供指导。结果表明,正常情况下,单叶蔓荆匍匐茎基部和中部生长缓慢,顶部生长快。轻度(沙埋匍匐茎基部)和中度(沙埋匍匐茎基部和中部)半埋和全埋使匍匐茎顶部生长加速,茎长增长量较对照高出1.5到3.1倍;但重度(沙埋整个匍匐茎)半埋和全埋使匍匐茎顶部净增长量减少12%和13%。在20d沙埋中,对照整个匍匐茎各段均无不定根长出,但不同程度半埋和全埋沙埋处理下沙下匍匐茎上均长出不定根,重度半埋使不定根生长受抑;同时匍匐茎上各段茎生物量上升,枝叶生物量下降,且随着沙埋程度的增加而增减幅度提高,在重度半埋和全埋达到最大。在轻度和中度半埋和全埋下,匍匐茎上未沙埋部位枝条生长加速。研究表明,在自然环境中,单叶蔓荆匍匐茎顶端是一个对环境变化反应敏感的部位,并与沙埋后单叶蔓荆茎延伸生长和植株能否生存密切相关。当匍匐茎顶部没被沙埋时,沙埋促进沙埋部位匍匐茎和枝叶中物质转移,加速匍匐茎顶部快速生长和物质积累以弥补沙埋带来的损伤维持物质和能量的代谢平衡。沙埋后,单叶蔓荆以茎顶端快速生长、形成不定根、枝条生长维持茎水分平衡和能量和物质代谢平衡,以快速生长摆脱沙埋影响的生长方式为其对沙埋环境的重要适应对策。因此,在海岸沙地单叶蔓荆种群管理和维护中,在强风移沙引起的重度沙埋后,及时剥离匍匐茎顶部沙子对维护单叶蔓荆种群的延续生存和扩散均有重要作用。     

Respiration and plasma membrane ATPase in strawberry stolons

The biochemical, physiological and anatomical properties of strawberry (Fragaria ananassa Duch.) cv. 'Cambridge Favourite' stolons were studied during growth. ATPase activity was measured, in microsomal and plasma membrane fractions, along with chlorophyll determination, in-situ photosynthesis measurements and scanning electron microscopy (SEM) and X-ray microanalysis of stolon cross-sections. Potassium-stimulated ATPase activity and proton-pumping, both together indicating the presence of plasma membrane ATPase, was greatest in the stolon tip, the tissue with the fastest growth and respiratory activity. The enzyme activity and respiration gradient from the tip of the stolon to the base was concomitant with xylem development which was more differentiated in the base than in the tip. These cross-sections also showed 30% greater amounts of calcium and potassium of the cryo-preserved basal part relative to the stolon tip. This gradient existed independent of the presence of daughter plants. A hypothesis is presented which suggests that for the long-distance longitudinal transport of nutrients this gradient between stolon tip and base is likely to be involved in stolon growth.     

Cytological Observations of the Large Symbiotic Foraminifer Amphisorus kudakajimensis Using Calcein Acetoxymethyl Ester

Large benthic foraminifera are unicellular calcifying reef organisms that can form symbiotic relationships with a range of different microalgae. However, the cellular functions, such as symbiosis and calcification, and other aspects of cellular physiology in large benthic foraminifera are not fully understood. Amphisorus kudakajimensis was used as a model to determine the detailed cellular characteristics of large benthic foraminifera. We used calcein acetoxymethyl ester (calcein AM) as a fluorescent indicator for live confocal imaging. We demonstrated that calcein AM is a useful fluorescent indicator to stain the fine network of reticulopodia and the cytoplasm in living A. kudakajimensis. We showed that at least two types of reticulopodia exist in A. kudakajimensis: the straight bundle of reticulopodia that spreads from the aperture and the fine reticulopodia along the surface of the aperture and chamber walls. The cytoplasm in outer chambers was highly branched and contained a few dinoflagellates. In contrast, the inner chamberlets contained condensed cytoplasm and many dinoflagellates, suggesting that the cytoplasm of A. kudakajimensis performs different functions based on its location within the large test. Our confocal detailed image analysis provides real-time cellular morphology and cell physiology of living foraminifera.     

Experimental control of budding and stolon elongation in Perophora orientalis. A compound ascidian

The elongation of stolon and the formation of an endoblastic vesicle leading to the differentiation of a blastozooid in an isolated stolon piece of Perophora orientalis were described. A treatment of isolated stolon pieces with 2 × 10^?2 M thiourea for 5 hr completely inhibited stolon elongation and at the same time accelerated the formation of an endoblastic vesicle. Inversely, 10^?5 M thyroxine and 10^?5 M triiodothyronine markedly stimulated stolon elongation with concomitant suppression of the formation of an endoblastic vesicle. The isolated stolon piece was thus proved to be experimentally directed either to the elongation of stolon or to the formation of an endoblastic vesicle, and to be a potential system for the study of the control mechanisms between the two alternative pathways, growth and differentiation.     

Comparison of Horizontal Spread of White Clover (Trifolium repensL.) Grown Under Two Artificial Light Sources Differing in their Content of Blue Light

The effects of blue light on the growth and development of differentbranches were studied to determine if variations in the bluelight supply modified the horizontal spread of white clover.Cuttings of white clover (‘Huia’) were grown for56 d in two controlled chambers under conditions similar exceptfor level of blue light (BL). The horizontal spread of whiteclover was characterised by the phyllochron, internode lengthand branching or flowering of different axes. The responsesto a reduction in BL were different according to axis degree:(1) on the main axis, lowering BL slightly decreased the phyllochronand had no effect on internode length or stolon length; (2)on older primary branches, it decreased their phyllochron, butreduced stolon length due to a reduction in internode length;(3) on secondary branches, it increased the phyllochron anddecreased internode length, triggering a strong reduction instolon length (up to 54%). Moreover, an increase in BL reversedthese effects. The switch to lower BL or higher BL had no effecton internode length of primary branches, but triggered changesin internode length of the main axis. These differential effectsof variations in BL on the morphogenesis of different branchesare discussed in relation to the clonal integration of variationsin light composition. Changes in the horizontal spread of whiteclover induced by BL could play a role, combined with responsesto low red:far-red ratio and low photosynthetic photon flux(PPF) in the strategy of horizontal colonisation and shade-avoidanceof white clover.Copyright 1998 Annals of Botany Company Blue light, branching, horizontal spread, morphogenesis, phyllochron, plant development, plant morphology, stolon growth,Trifolium repensL., white clover.     

Simple growth chambers for culturing microalgae with precision at different temperatures and irradiance

Profiles describing the relationships between growth, irradiance and temperature are important in the evaluation of microalgae and cyanobacteria for biomass production, as well as for their general characterization. To get correct results culturing chambers with plane parallel optical faces are needed. Only these give a defined light climate in the culture, but such devices are not found commercially. We here describe the testing of thermostated growth chambers with 200-mL culture volumes, easily constructed from disposable 144-mm diameter plastic Petri dishes. Their properties were examined by growing Spirulina platensis concurrently in 15 parallel cultures under identical conditions of illumination and temperature, showing efficient and reproducible growth between them. The chambers are naturally also very suitable for growing microalgae in general. This revised version was published online in August 2006 with corrections to the Cover Date.     

Controlled-Environment Sunlit Plant Growth Chambers

Controlled environment sunlit plant growth chambers have been built because of a great interest in plant responses to environmental variables under light intensities approaching those of natural sunlight conditions. Individual research projects have designed sunlit chambers that differ in size, structure, material, and environmental control systems dependent on the goals of the projects. Most literature describes plant organism responses to environmental variables, whereas reports of system design and performance are few. The objective of this article is to present a review of the engineering aspects of the design, environmental control, and performance of sunlit growth chambers that have been described in the literature. Most controlled environment sunlit growth chambers have been constructed with experimental plants grown in either pots or soil bins. Although a few sunlit growth chambers were designed for field grown plants, precise environmental control was not available. Further progress in the development of precise controlled environment sunlit growth chambers should include portability (or movability) so these chambers can be used in multiple field sites for greater cost-effectiveness. Modifications for improvements in guidelines for the design and operation of controlled environment growth chamber studies are also proposed.     

Distribution and fine structure of the lymphatic system in the human testis

Summary The distribution of lymph vessels in the human testis was investigated using ink injection methods, and light and electron microscopy. Lymph capillaries occur in the septula testis but are absent in the intertubular tissue. They consist of endothelial cells provided with an incomplete basal lamina and anchoring filaments of the adjacent connective tissue. Frequently, the endothelial cells are separated by gaps measuring up to 2m. The lymph capillaries of the septula testis are connected to lymph vessels in the rete testis and tunica albuginea. These vessels have occasional smooth muscle cells and valves. At the posterior margin of the testis, the network of lymph vessels merges into collecting ducts, which together with vessels derived from the rete testis are drained by the lymphatic system in the spermatic cord.Dedicated to Prof. Henriette Oboussier, Hamburg, on the occasion of her 65th birthday