Sea urchin fertilization envelope: Uncoupling of cortical granule exocytosis from envelope assembly and isolation of an envelope intermediate from Strongylocentrotus purpuratus embryos

The sea urchin fertilization envelope (FE) is an extraembryonic coat which develops from the egg vitelline envelope (VE) and the secreted paracrystalline protein fraction of the cortical granules at fertilization. The FE undergoes further developmental changes postinsemination which are characterized by changes in envelope permeability, solubility in reducing and denaturing solvents, and morphology. We have developed a procedure to uncouple cortical granule exocytosis from assembly of the paracrystalline protein fraction onto the VE template. Egg suspensions were inseminated in normal seawater and diluted into Ca²⁺- and Mg²⁺-free seawater at 15 sec postinsemination. Phase-contrast and electron microscopic observations showed that the embryos formed a normally elevated, extremely thin envelope through which the cortical granule exudate permeated. Secretion studies showed that eggs which were diluted into divalent ion-free seawater postinsemination secreted as much protein into the surrounding seawater as eggs which had their VEs removed prior to the experiment. We have termed the envelope elevated in divalent ion-free seawater the VE1 and we believe that it is the VE structural component of the FE based on its thickness and morphology. VE1s were isolated by gentle physical means and the preparations appeared to be greater than 80% pure based on radioactive mixing experiments and on malate dehydrogenase and glucose-6-phosphate dehydrogenase marker studies. VE1s were at least 80% soluble based on extraction of radioiodinated preparations with reducing and denaturing solvents. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of VE1s showed eight major polypeptides which ranged from 30,500 to 270,000 in molecular weight.     

Comparative floral structure and systematics in Apodanthaceae (Rafflesiales)

Comparative studies on floral morphology, anatomy, and histology were performed to identify shared features of the genera of Apodanthaceae (Rafflesiales): Apodanthes, Pilostyles, and Berlinianche. Berlinianche was studied for the first time in detail and its affinity to Apodanthaceae was confirmed. It has a previously undescribed hair cushion on the inner perianth organs and inaperturate pollen. Shared features of members of Apodanthaceae are: unisexual flowers; three (or four) alternating di-/tetra- or tri-/hexamerous whorls of scales of which the inner one or two correspond to a perianth; a synandrium with pollen sacs typically arranged in two rings; opening by a dehiscence line between the two rings of pollen sacs; large vesicular hairs above the synandrium; a gynoecium with four united carpels; inferior and unilocular ovaries with four parietal placentae, ovules tenuinucellate, anatropous with two well developed integuments, oriented in various directions; a nectary disk. Apodanthaceae share some special structural features with Malvales.     

Systems biological approach to investigate the lack of familial link between Down's Syndrome & Neural Tube Disorders

Systems Biology involves the study of the interactions of biological systems and ultimately their functions. Down''s syndrome (DS) is one of the most common genetic disorders which are caused by complete, or occasionally partial, triplication of chromosome 21, characterized by cognitive and language dysfunction coupled with sensory and neuromotor deficits. Neural Tube Disorders (NTDs) are a group of congenital malformations of the central nervous system and neighboring structures related to defective neural tube closure during the first trimester of pregnancy usually occurring between days 18-29 of gestation. Several studies in the past have provided considerable evidence that abnormal folate and methyl metabolism are associated with onset of DS & NTDs. There is a possible common etiological pathway for both NTDs and Down''s syndrome. But, various research studies over the years have indicated very little evidence for familial link between the two disorders. Our research aimed at the gene expression profiling of microarray datasets pertaining to the two disorders to identify genes whose expression levels are significantly altered in these conditions. The genes which were 1.5 fold unregulated and having a p-value <0.05 were filtered out and gene interaction network were constructed for both NTDs and DS. The top ranked dense clique for both the disorders were recognized and over representation analysis was carried out for each of the constituent genes. The comprehensive manual analysis of these genes yields a hypothetical understanding of the lack of familial link between DS and NTDs. There were no genes involved with folic acid present in the dense cliques. Only – CBL, EGFR genes were commonly present, which makes the allelic variants of these genes – good candidates for future studies regarding the familial link between DS and NTDs.

Abbreviations

NTD - Neural Tube Disorders, DS - Down''s Syndrome, MTHFR - Methylenetetrahydrofolate reductase, MTRR– 5 - methyltetrahydrofolate-homocysteine methyltransferase reductase.     

Floral development and floral phyllotaxis in Anaxagorea (Annonaceae)

Background and Aims Anaxagorea is the phylogenetically basalmost genus in the large tropical Annonaceae (custard apple family) of Magnoliales, but its floral structure is unknown in many respects. The aim of this study is to analyse evolutionarily interesting floral features in comparison with other genera of the Annonaceae and the sister family Eupomatiaceae. Methods Live flowers of Anaxagorea crassipetala were examined in the field with vital staining, liquid-fixed material was studied with scanning electron microscopy, and microtome section series were studied with light microscopy. In addition, herbarium material of two other Anaxagorea species was cursorily studied with the dissecting microscope. Key Results Floral phyllotaxis in Anaxagorea is regularly whorled (with complex whorls) as in all other Annonaceae with a low or medium number of floral organs studied so far (in those with numerous stamens and carpels, phyllotaxis becoming irregular in the androecium and gynoecium). The carpels are completely plicate as in almost all other Annonaceae. In these features Anaxagorea differs sharply from the sister family Eupomatiaceae, which has spiral floral phyllotaxis and ascidiate carpels. Flat stamens and the presence of inner staminodes differ from most other Annonaceae and may be plesiomorphic in Anaxagorea. However, the inner staminodes appear to be non-secretory in most Anaxagorea species, which differs from inner staminodes in other families of Magnoliales (Eupomatiaceae, Degeneriacae, Himantandraceae), which are secretory. Conclusions Floral phyllotaxis in Anaxagorea shows that there is no signature of a basal spiral pattern in Annonaceae and that complex whorls are an apomorphy not just for a part of the family but for the family in its entirety, and irregular phyllotaxis is derived. This and the presence of completely plicate carpels in Anaxagorea makes the family homogeneous and distinguishes it from the closest relatives in Magnoliales.     

Multicarpellate gynoecia in angiosperms: occurrence,development, organization and architectural constraints

Most angiosperms have gynoecia with two to five carpels. However, more than five carpels (here termed ‘multicarpellate condition’) are present in some representatives of all larger subclades of angiosperms. In such multicarpellate gynoecia, the carpels are in either one or more than one whorl (or series). I focus especially on gynoecia in which the carpels are in a single whorl (or series). In such multicarpellate syncarpous gynoecia, the closure in the centre of the gynoecium is imprecise as a result of slightly irregular development of the carpel flanks. Irregular bumps appear to stuff the remaining holes. In multicarpellate gynoecia, the centre of the remaining floral apex is not involved in carpel morphogenesis, so that this unspent part of the floral apex remains morphologically undifferentiated. It usually becomes enclosed within the gynoecium, but, in some cases, remains exposed and may or may not form simple excrescences. The area within the remaining floral apex is histologically characterized by a parenchyma of simple longitudinal cell rows. In highly multicarpellate gynoecia with the carpels in a whorl, the whorl tends to be deformed into an H‐shaped or star‐shaped structure by differential growth of the floral sectors, so that carpels become aligned in parallel rows, in which they face each other with the ventral sides. In this way, a fractionated compitum may still be functional. Multicarpellate gynoecia (with the carpels in one whorl or series) occur in at least one species in 37 of the 63 angiosperm orders. In contrast, non‐multicarpellate gynoecia are present in at least one species of all 63 orders. The basal condition in angiosperms is more likely non‐multicarpellate. Multicarpellate gynoecia are restricted to flowers that are not highly synorganized. In groups with synorganized androecium and gynoecium and in groups with elaborate monosymmetric flowers, multicarpellate gynoecia are lacking. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 1–43.     

New species of Malouetia (Apocynaceae): A trio from Amazonia

Three new species ofMalouetia (Apocynaceae) are described and illustrated:M. amazonica andM. pumila from Brazil andM. gentryi from Peru.Malouetia amazonica grows in inundated igapó forest, whereas the other two are found in non-inundated habitats:M. pumila incampa fechada, andM. gentryi in upland forest.     

Cunoniaceae in the Cretaceous of Europe: Evidence from Fossil Flowers

Fossil flowers of the Cunoniaceae from Late Cretaceous sedimentsof southern Sweden are described in detail. The flowers aresmall, bisexual, actinomorphic, tetramerous with broadly attachedvalvate sepals; they have narrowly attached petals; eight stamensin two whorls; a massive, lobed nectary; a semi-inferior, syncarpousgynoecium with axile placentation; numerous ovules; separatestyles; and peltate, probably secretory, trichomes. They sharemany features with extant representatives of both the Cunoniaceaeand Anisophylleaceae. However, the gynoecium structure in particularindicates a closer relationship to the Cunoniaceae. The floralcharacters are not specific for any extant genus of the familyand therefore a new genus and species, Platydiscus peltatusgen. et sp. nov., is formally described. This is the first recordof cunoniaceous floral structures from the Northern Hemisphereand the oldest record of Cunoniaceae flowers worldwide. Copyright2001 Annals of Botany Company Anisophylleaceae, Cunoniaceae, fossil flowers, Late Cretaceous, Oxalidales, Platydiscus peltatus gen. et sp. nov., Santonian-Campanian, southern Sweden     

Androecial development and systematics inFlacourtiaceae s. l.

Androecial development of 13 species belonging to six tribes ofFlacourtiaceae has been investigated. While inScolopieae andFlacourtieae the stamens develop centrifugally, inErythrospermeae, Oncobeae andPangieae they are initiated in a centripetal sequence or a sequence that is neither distinctly centripetal nor centrifugal. The distribution of these developmental patterns coincides with the distribution of other characters (e.g. cyanogenic compounds, salicoid leaf teeth) and therefore supports a split of the family intoFlacourtiaceae s. str. (containing theScolopieae, Homalieae, Prockieae, Flacourtieae, Casearieae andBembicieae) andKiggelariaceae (withErythrospermeae, Oncobeae andPangieae) and is in accordance with results of recentrbcL studies.     

A Comparison of Floral Structures of Anisophylleaceae and Cunoniaceae and the Problem of their Systematic Position

Flowers of Anisophyllea(Anisophylleaceae, Cucurbitales) andCeratopetalum(Cunoniaceae, Oxalidales) are surprisingly similar in appearance.To date, these families have never been interpreted as closelyrelated, and even in present molecular (rbcL) studies they appearin different orders of eurosids I (APG, Annals of the MissouriBotanical Garden85:531–553, 1998). In this investigation,flowers of selected taxa of both families are morphologicallyand anatomically compared. In addition, previous work on thetwo families is reviewed. The results strongly emphasize thegreat similarity in all floral organs. Some special similaritiesinclude the occurrence of trimerous flowers, isomerous organwhorls (including the gynoecium), valvate sepals, digitate petals,obdiplostemony, incurved filaments in bud with similar anthers,similar pollen, similar nectaries, carpels with free styles,a canal in the centre of each individual carpel as well as inthe centre of the entire gynoecium along the symplicate zone,and similar ovules with a slit-shaped micropyle. In addition,recently recovered Late Cretaceous floral fossils that sharefeatures of both families further emphasize a potential closerelationship. However, if more extensive molecular studies areperformed in the future that support the current disparate positionof the two families, then an explanation of the biological/functionalsimilarities in floral structure should be attempted: specifically,whether this suite of features is a symplesiomorphy for basalrosids, or an autapomorphy for each family. Copyright 2001 Annalsof Botany Company Anisophylleaceae, Cucurbitales, Cunoniaceae, eudicots, floral structure, molecular systematics, Myrtales, Oxalidales, Saxifragales     

Conversion of phenylalanine into tyrosine by portulaca callus

The incorporation of [(14)C]phenylalanine and [1,6-(14)C]shikimic acid into tyrosine was investigated in the callus of Portulaca grandiflora, var. JR (L.). By inhibiting phenylalanine with 1-alpha-aminooxy-beta-phenyl-propionic acid and tyrosinase with 1-cysteine-HCl and hydrazine-hydrate, the possible synthesis of tyrosine from phenylalanine was demonstrated. Tetrahydropterine sulfate was an effective activator of this pathway and tyrosine accumulation via 4-hydroxy-prephenic acid is regulated by feedback inhibition. l-alpha-Amminooxy-beta-phenylpropionic acid inhibits both phenylalanine ammonia-lyase and the production of phenylalanine from prephenic acid.