Stipule arrangement in the genus Caesalpinia (Leguminosae)

Stipular development in Caesalpinia displays two patterns. More commonly, stipules, throughout the development of the leaf, assume a subordinate position never keeping pace with the petiole-blade portion. In two out of eight species the stipules showed strong proleptic development exceeding in size their own leaf within a plastochron of initiation and soon thereafter covering that leaf. Information on stipule development, as well as other features of the embryonic leaf may be of use to the taxonomist and such data can now be obtained relatively easily using SEM.     

High genetic differentiation among remnant populations of the endangered Caesalpinia echinata Lam. (Leguminosae–Caesalpinioideae)

Forest fragments along the Atlantic coastland of Brazil have been highly impacted by extensive human activities for the last 400 years. Caesalpinia echinata (Leguminosae– Caesalpinioideae), brazilwood, was overexploited during this period due to its economical importance as a dye. As a result, the species has become endangered and today its total population size is very restricted. We have assessed the distribution of genetic variation between five natural populations of brazilwood by means of RAPD (random amplified polymorphic DNA) markers. Of the total genetic variability, 28.5% was attributable to differences between two geographical groups, 29.6% to population differences within groups and 42.0% to individual differences within populations. The high level of population differentiation observed is in contrast to that expected for a primarily outcrossed woody perennial plant, and suggests that there may be a degree of inbreeding. Our results are in agreement with previous studies which postulated that C. echinata has always occurred in clumps, being common in some places but rare in between. From a conservation point of view, different populations representing different regions should be protected and, yet, plants with different origins should not be synthesized into populations in a recovery process at the risk of loss and dilution of genetic information. This study demonstrates that RAPD markers were effective in establishing a clear correlation between genetic and geographical distance and in identifying areas of maximum diversity, and may be used as an initial approach to assess the partitioning of genetic variation in this endangered species.     

Biodeterioration of brazilwood Caesalpinia echinata Lam. (Leguminosae—Caesalpinioideae) by rot fungi and termites

The heartwood of Caesalpinia echinata Lam. (Leguminosae) (commonly called brazilwood) is used for violin bow manufacture due to the unique vibrational and physical properties found in the wood. In the present work, the effects of Pycnoporus sanguineus (white-rot fungus), Gloeophyllum trabeum (brown-rot fungus), Chaetomium globosum (soft-rot fungus), and Cryptotermes brevis (dry-wood termite) on weight losses and chemical composition of extractives and cell-wall polysaccharides of C. echinata wood were investigated under laboratory conditions and compared to those obtained for Anadenanthera macrocarpa, Eucalyptus grandis, and Pinus elliottii. The heartwood of C. echinata was found to be as resistant as A. macrocarpa to the decay fungi tested and to the attack of the dry-wood termite. Pinitol and galactopinitol A were the main sugar alcohols found in the extractives of wood of C. echinata, their presence, however, did not appear related to the resistance to fungal decay. Although only incipient stages of decay were found, the modifications in cell-wall polysaccharide composition of heartwood of C. echinata by rot fungi were related to decrease in polymers other than xylans. The high resistance of C. echinata to xylophages is probably due to the presence of toxic extractives in the wood.     

中国云实属植物一新记录

报道了一种云实属 ( Caesalpinia L.)植物菱叶云实在中国的分布新记录。     

Caenorhabditis elegans integrates food and reproductive signals in lifespan determination

Dietary restriction extends lifespan and inhibits reproduction in many species. In Caenorhabditis elegans, inhibiting reproduction by germline removal extends lifespan. Therefore, we asked whether the effect of dietary restriction on lifespan might proceed via changes in the activity of the germline. We found that dietary restriction could increase the lifespan of animals lacking the entire reproductive system. Thus, dietary restriction can extend lifespan independently of any reproductive input. However, dietary restriction produced little or no increase in the long lifespan of animals that lack germ cells. Thus, germline removal and dietary restriction may potentially activate lifespan-extending pathways that ultimately converge on the same downstream longevity mechanisms. In well-fed animals, the somatic reproductive tissues are generally completely required for germline removal to extend lifespan. We found that this was not the case in animals subjected to dietary restriction. In addition, in these animals, loss of the germline could either further lengthen lifespan or shorten lifespan, depending on the genetic background. Thus, nutrient levels play an important role in determining how the reproductive system influences longevity.     

ATRACTOMORPHA PORCATA SP. NOV., A NEW MEMBER OF THE SPHAEROPLEACEAE (CHLOROPHYCEAE) FROM CALIFORNIA1

Atractomorpha porcata sp. nov. is described from culture isolates derived in 1981 from zygotes present in a 28 year old, dried soil sample collected from near Lemon-cove, Tulare County, California. Vegetative individuals are coenocytic, spindle-shaped unicells with long, thin-pointed apices. Asexual reproduction is by means of large, biflagellate zoospores or, frequently, by aplanospores. Sexual reproduction is usually monoecious, with a single spindle-shaped gametangial cell producing small, biflagellate male gametes at either end, and larger female gametes in the midportion. Female gametes are often biflagellate, but more commonly they lack flagella and are liberated by squeezing through slit-like openings in the gametangial wall. Sexual reproduction may thus be considered as either oogamous or anisogamous, depending on whether or not a particular female gamete has flagella; most often it is oogamous. Atractomorpha porcata is readily distinguished from A. echinata, the only other known member of the genus, by (1) its greater tendency toward oogamy (versus anisogamy), (2) its bisexual gametangia, (3) its frequent production of aplanospores in asexual reproduction, (4) its unusual primary membranes that frequently bear long, delicate bristles, and (5) its distinctive zygote wall ornamentation.     

Contributo preliminare alla sistematica di Chamaecytisus hirsutus e Chamaecytisus supinus

Abstract

Chamaecytisus hirsutus and C. supinus: a preliminary report. – Chamaecytisus hirsutus (L.) Link and C. supinus (L.) Link have been described as twostrictly related species, which differ mainly in the form of inflorescence: C. hirsutus has lateral flowers, C. supinus has terminal flowers. Besides, most Floras provide a set of additional differential characters that should permit to di-C. hirsutus and C. supinus.

The author analyses such differential characters and demonstrates that all of them are inconsistent: therefore the inflorescence seems to be the only difference between C. hirsutus and C. supinus.

The inflorescence itself, however, is not a constant character: indeed, it is known that C. supinus may develop vernal latera flowers besides the normal aestival terminal ones.

The geographic distributions of the two inflorescence types are accurately examined (a report of the distributions is given, a list of herbarium specimens is presented in appendix, a point distribution map of the two types is given in figs. 1 and 2); the only differences are the following ones: plants with flowers in leafy racemes (usually identified as C. hirsutus) seem to be absent from Spain and from Southern Poland, and to be unfrequent in Central and Western France; instead, plants with flowers in heads (usually identified as C. supinus) are very unfrequent in the Southern Balcan Peninsula, and are absent from Southern Greece and the Italian Peninsula.

After a discussion of the biological significance of the capitate and lateral inflorescence, and on the basis of in vivo observations, the author argues that probably the same taxonomic unit is present in the whole area, showing some differences in its flowering behaviour; in the largest part of the areal – including the center of distribution of the species – most individuals flower twice, and therefore have been recorded as two different species; a trend toward the capitate inflorescence is remarkable in the North and in the West; instead, in the South and the East the trend is toward lateral flowers (fig. 3).

Further biometrical and biochemical studies on the species are now in progress; more observations in field in different parts of Europe are necessary in order to get conclusive evidence of the identity of these two so-called «species».     

豚鼠卵巢囊淋巴孔的发现及卵巢囊超微结构研究

本实验通过扫描电镜等方法研究豚鼠卵巢囊及卵巢囊淋巴孔的结构,并探讨了卵巢囊及其淋巴孔的种属差异.实验结果首次报道豚鼠卵巢囊内、外层上皮均存在淋巴孔;豚鼠卵巢囊结构在输卵管走行、囊闭合程度及囊表面超微结构等方面与金仓鼠存在差异.结果提示豚鼠卵巢囊内、外层淋巴孔是沟通卵巢囊腔、卵巢囊淋巴系及腹膜腔的形态基础,可能是三者间物质转运的重要途径.卵巢囊淋巴孔可能影响物种的繁殖并参与囊腔内局部免疫反应.卵巢囊结构和发育程度与对应的输卵管伞端等结构及其他生殖特点相适应,研究结果丰富了生殖形态学和比较解剖学资料.     

Stomatal control of transpiration from a developing sugarcane canopy

Abstract. Stomatal conductance of single leaves and transpiration from an entire sugarcane (Saccharum spp. hybrid) canopy were measured simultaneously using independent techniques. Stomatal and environmental controls of transpiration were assessed at three stages of canopy development, corresponding to leaf area indices (L) of 2.2, 3.6 and 5.6. Leaf and canopy boundary layers impeded transport of transpired water vapour away from the canopy, causing humidity around the leaves to find its own value through local equilibration rather than a value determined by the humidity of the bulk air mass above the canopy. This tended to uncouple transpiration from direct stomatal control, so that transpiration predicted from measurement of stomatal conductance and leaf-to-air vapour pressure differences was increasingly overestimated as the reference point for ambient vapour pressure measurement was moved farther from the leaf and into the bulk air. The partitioning of control between net radiation and stomata was expressed as a dimensionless decoupling coefficent ranging from zero to 1.0. When the stomatal aperture was near its maximum this coefficient was approximately 0.9, indicating that small reductions in stomatal aperture would have had little effect on canopy transpiration. Maximum rates of transpiration were, however, limited by large adjustments in maximum stomatal conductance during canopy development. The product of maximum stomatal conductance and L. a potential total canopy conductance in the absence of boundary layer effects, remained constant as L increased. Similarly, maximum canopy conductance, derived from independent micrometeorological measurements, also remained constant over this period. Calculations indicated that combined leaf and canopy boundary layer conductance decreased with increasing L such that the ratio of boundary layer conductance to maximum stomatal conductance remained nearly constant at approximately 0.5. These observations indicated that stomata adjusted to maintain both transpiration and the degree of stomatal control of transpiration constant as canopy development proceeded.     

Occurrence of sorbitol in Zea mays

The identity of sorbitol (d-glucitol) from maize seeds was confirmed by GC/MS of the TMSi-ether and by co-chromatography with authentic sorbitol. Sorbitol was found in seeds and silks but not in pollen or leaves. Both endosperm and embryo contained sorbitol, but endosperm accounted for most of the sorbitol recovered from intact seeds.     

沙棘属和胡颓子属叶表皮形态与分类的扫描电镜研究 Ⅱ.沙棘属叶表皮形态与分类

扫描电镜观察结果表明, 叶表皮毛、角质层和气孔器可作为沙棘属各分类单位分类依据之一。柳叶沙棘全为星状毛, 西藏沙棘全为盾状毛, 为两个独立的种。肋果沙棘叶表皮毛虽与其他沙棘种(亚种)相似, 但其气孔器较大, 呈盘状而有区别。从叶表皮毛和气孔器上, 中国沙棘、云南沙棘、中亚沙棘、蒙古沙棘和江孜沙棘相似。但江孜沙棘星状毛毛臂具螺旋状细条纹饰与柳叶沙棘相近。     

妊娠和激素干预对豚鼠卵巢囊淋巴孔的影响

本实验以台盼蓝为示踪剂,观察成年雌豚鼠在妊娠、注射促排卵激素和雄激素时,卵巢囊淋巴孔对示踪剂的吸收情况,并结合扫描电镜和计算机图像处理,对豚鼠卵巢囊内壁的淋巴孔进行观察和统计,以研究妊娠和激素干预对豚鼠卵巢囊淋巴孔开放和淋巴吸收功能的影响。结果表明,妊娠组卵巢囊吸收示踪剂的量最多,促排卵组次之,雄激素组最少,且组间两两比较均有显著性意义(P<0.05)。在每1000μm~2的视野中,妊娠组卵巢囊淋巴孔的开放面积为189.9±48.7μm~2,促排卵组为104.4±31.2μm~2,雄激素组为40.5±18.7μm~2,组间两两比较均有显著性意义(P<0.05)。妊娠组卵巢囊内层纤毛柱状上皮的分泌颗粒数量最少,而促排卵组的分泌颗粒较多,且纤毛最活跃。本实验研究结果表明,妊娠和激素干预能影响豚鼠卵巢囊淋巴孔的开放和吸收,囊内卵巢的功能状态与豚鼠卵巢囊淋巴孔的调控密切相关。     

Stomatal responses to humidity in air and helox

Abstract. Stomatal responses to humidity were studied in several species using normal air and a helium: oxygen mixture (79:21 v/v, with CO₂ and water vapour added), which we termed 'helox'. Since water vapour diffuses 2.33 times faster in helox than in air, it was possible to vary the water-vapour concentration difference between the leaf and the air at the leaf surface independently of the transpiration rate and vice versa. The CO₂ concentration at the evaporating surfaces ( c_i ), leaf temperature and photon flux density were kept constant throughout the experiments. The results of these experiments were consistent with a mechanism for Stomatal responses to humidity that is based on the rate of water loss from the leaf. Stomata apparently did not directly sense and respond to either the water vapour concentration at the leaf surface or the difference in water vapour concentration between the leaf interior and the leaf surface. In addition, stomatal responses that caused reductions in transpiration rate at low humidities were accompanied by decreases in photosynthesis at constant c_i , suggesting heterogeneous (patchy) stomatal closure.