Structure and Development of Stomata in Some Labiatae

The structure and ontogeny of stomata have been studied in 33species of the Labiatae. The mature stomata are diacytic, transitionalbetween paracytic and diacytic, and anomocytic. The anomocyticstomata are haplocheilic or perigenous. The diacytic and thetransitional type of stomata are syndetocheilic or mesogenousas the two subsidiary cells and a pair of guard cells arisefrom the same meristemoid. The diacytic and the transitionalstomata are formed through three successive mitotic divisions.Abnormal stomata with single guard cells, arrested developments,and contiguous stomata have been observed. Contiguous stomataare formed either from two adjacently placed meristemoids orare the result of spatial readjustment during maturation ofthe leaf.     

Germination of Species of Labiatae in Response to Gibberellins

Gibberellic acid at between 1 and 1000 mg/1 was used to treat fruits of different Labiatae species kept at an unfavourable temperature for normal germination (25°C). Germination requirements were diverse, but all germinated in response to gibberellic acid. Minimum effective concentrations varied widely from 1 mg/1 with Salvia glutinosa up to 1000 mg/1 with Lycopus europaeus and Scutetlaria galericulata.
When species were tested under conditions in which a proportion of the fruits germinated naturally the results suggested that, even under marginal conditions, relatively high concentrations of gibberellic acid were required to promote germination, although hypocotyl extension in each of the species responded to much lower levels (0.1 mg/1).
Treatments applied to fruits of Lycopus europaeus and two Galeopsis species showed that modifications to the physical conditions of the test, such as light and temperature, produced only small changes in response to gibberellic acid. This effect was found even when situations in which a proportion of seeds germinated without gibberellin treatment were compared with conditions extremely unfavourable for germination.
Comparisons of the effects of gibberellic acid (A3) and gibberellin A4 suggested that the latter promoted germination at approximately one hundred times the dilution of the former when tested on Lycopus europaeus and Galeopsis pyrenaica.     

Cell Wall Composition in Relation to the Taxonomy of Some Actinoplanaceae

Hydrolytic residues of the cell walls of 48 strains of Actinoplanaceae, previously assigned to 10 species and the four genera, Actinoplanes, Ampullariella, Amorphosporangium, and Pilimelia, were examined by paper chromatography and column chromatography. Comparisons were made for taxonomic purposes between the groupings obtained, by use of chemical characters and the groupings currently recognized morphologically. Most of the species investigated had qualitatively distinct cell wall compositions. Often, however, the cell wall compositions of species in different genera were more similar, in some respects, than were those of species in the same genus. Quantification of the cell wall amino acids and amino sugars substantiated that cross-generic similarities existed. Based on these results and the morphological conclusions reached by other investigators, a single-genus concept is suggested for the Actinoplanaceae examined.     

Some Factors in Relation to Bulliform Cell Silicification in the Grass Leaf

The formation of discrete ‘tablets’ of hydratedsilica in the bulliform cells of the leaf blade was followedover a 16-day period in three species of the Gramineae representingdifferent habitats. Seedlings of Oryza sativa (rice) and Cynodondactylon (Bermuda Grass) were cultured under growth-cabinetconditions at levels of 50 and 500 ppm dissolved silica (SiO₂)in the nutrient solution. In addition, bulliform depositionwas studied in mature tiller leaves of Sieglingia decumbens(Heath Grass). Attached leaves, as well as those excised fromthe culm, were used. Initial stages of tablet formation were observed by the 2-dayharvest in the central and basal zones of the fully expandedseedling blades. Deposition did not occur at a stage when bulliformturgor changes might influence blade evolvement. At the 16-dayharvest, deposition was heaviest in the tip zone, and decreasedprogressively towards the base of the blade. In addition, proportionatelyhigher tablet counts (P = 0.05) generally were absent from theleaves grown at the higher silica level. This indicated a limitedavailability of deposition sites. These results are discussed in relation to (i) cellular maturation;(ii) internal leaf anatomy; (iii) leaf expansion; (iv) a basipetalsenescence gradient within the leaf blade. Certain of theseare considered to be possible limiting factors to silica depositionin the grass leaf.     

Transport of 14C-Assimilates in Seedlings of Phaseolus vulgaris L. in Relation to Vascular Anatomy

Patterns of ¹⁴C-photosynthate translocation in bean (Phaseolusvulgaris L.) seedlings have been investigated in relation tovascular-bundle continuity between exporting and importing organsby use of radioassay and tissue-clearing techniques. Assimilatefrom the primary leaves reaches the first trifoliate leaf byan indirect route. There is no direct vascular connection betweenthe primary leaves and distal tissues. Bundles of the primaryleaf petiole connect with an anastomosis at the node, and allbundles which originate from this structure descend the stem.Assimilate from primary leaves moves down the stem, and is thentransferred to an ascending pathway, the bundles of which traversethe anastomosis at the second node. The lateral leaflets ofthe first trifoliate leaf are served differentially by primaryleaves with respect to assimilate supply. Differences are relatedto position, and may be accounted for by differences in vascularcontinuity.     

一串红胚胎发育过程中多胺含量的变化

选取发育正常和败育一串红(Saliva splendens)5个不同时期的胚胎,分别提取、测定多胺(精胺、亚精胺、腐胺与尸胺)的含量变化.通过比较一串红胚胎发育不同阶段多胺物质的变化规律,探讨多胺在一串红胚胎发育中的生理作用.结果表明,一串红的胚胎败育和胚珠中较低的多胺含量及其在发育进程中较大的降幅有关;在盛花期,胚胎发育的关键时期,正常胚珠中哑精胺的含量有一个明显的峰值,而败育的胚珠中则无,这表明亚精胺含量变化在胚胎发育中起关键调节作用.     

Regulation of Vascular Development

   apd: 7 June 2001     

Polymorphism of Apolipoproteine E in Relation with Alzheimer and Vascular Dementia

Summary 1. The epsilon 4 allele of the apolipoprotein E gene increases the risk of late onset familial and sporadic Alzheimer disease. Relation of epsilon 4 allele of the apolipoprotein E gene to various types of dementia and the onset of dementia were analyzed in the present study.2. The study comprised 139 patients (50 men and 89 women) with dementia, mean age 73.61 years (range 47–98). The diagnosis of dementia was made according to Diagnostic and Statistical Manual of Mental Disorders, and subtypes diagnoses were made according to NINCDS-ADRDA and NINDS-AIREN criteria. Minimental State Examination (MMSE) was used for the screening of dementia. Apolipoprotein E polymorphism was determined by the PCR-RFLP technique-polymerase chain reaction and subsequent digestion with specific restriction endonuclease. For statistical analyses chi-square test and the crude Gart′s odds ratio (OR) and 95% confidence intervals (CI) were used.3. From 139 dementia patients (MMSE ≤24 points) in 61 (45%) Alzheimer disease (AD) was present, in 44 patients (31%) vascular dementia (VD), and in 34 (24%) mixed dementia (MD) were revealed. In comparison with control group the presence of at least one ApoE-ɛ4 allele was significantly higher only in the group with AD (p < 0.001), (OR=2.76; 95%: 1.42–5.36). The frequency of ɛ4 allele carriers was significantly overrepresented in AD group compared with VD (χ²=5.94; p=0.0148). Differences between AD and MD or VD and MD were not confirmed.     

Obstructions in Vascular Networks: Relation Between Network Morphology and Blood Supply

We relate vascular network structure to hemodynamics after vessel obstructions. We consider tree-like networks with a viscoelastic fluid with the rheological characteristics of blood. We analyze the network hemodynamic response, which is a function of the frequencies involved in the driving, and a measurement of the resistance to flow. This response function allows the study of the hemodynamics of the system, without the knowledge of a particular pressure gradient. We find analytical expressions for the network response, which explicitly show the roles played by the network structure, the degree of obstruction, and the geometrical place in which obstructions occur. Notably, we find that the sequence of resistances of the network without occlusions strongly determines the tendencies that the response function has with the anatomical place where obstructions are located. We identify anatomical sites in a network that are critical for its overall capacity to supply blood to a tissue after obstructions. We demonstrate that relatively small obstructions in such critical sites are able to cause a much larger decrease on flow than larger obstructions placed in non-critical sites. Our results indicate that, to a large extent, the response of the network is determined locally. That is, it depends on the structure that the vasculature has around the place where occlusions are found. This result is manifest in a network that follows Murray’s law, which is in reasonable agreement with several mammalian vasculatures. For this one, occlusions in early generation vessels have a radically different effect than occlusions in late generation vessels occluding the same percentage of area available to flow. This locality implies that whenever there is a tissue irrigated by a tree-like in vivo vasculature, our model is able to interpret how important obstructions are for the irrigation of such tissue.     

Cell-Cell Interactions during Vascular Development

Received 1 September 2001/ Accepted in revised form 15 October 2001