Nitrogen supply as a factor influencing photoinhibition and photosynthetic acclimation after transfer of shade-grown Solanum dulcamara to bright light

We have compared the ability of shadegrown clones of Solamum dulcamara L. from shade and sun habitats to acclimate to bright light, as a function of nitrogen nutrition before and after transfer to bright light. Leaves of S. dulcamara grown in the shade with 0.6 mM NO ₃ ^- have similar photosynthetic properties as leaves of plants grown with 12.0 mM NO ₃ ^- . When transferred to bright light for 1–2 d the leaves of these plants show substantial photoinhibition which is characterized by about 50% decrease in apparent quantum yield and a reduction in the rate of photosynthesis in air at light saturation. Photoinhibition of leaf photosynthesis is associated with reduction in the variable component of low-temperature fluorescence emission, and with loss of in-vitro electron transport, especially of photosystem II-dependent processes.We find no evidence for ecotypic differentiation in the potential for photosynthetic acclimation among shade and sun clones of S. dulcamara, or of differentiation with respect to nitrogen requirements for acclimation. Recovery from photoinhibition and subsequent acclimation of photosynthesis to bright light only occurs in leaves of plants provided with 12.0 mM NO ₃ ^- . In these, apparent quantum yield is fully restored after 14 d, and photosynthetic acclimation is shown by an increase in light-saturated photosynthesis in air, of light-and CO₂-saturated photosynthesis, and of the initial slope of the CO₂-response curve. The latter changes are highly correlated with changes in ribulose-bisphosphate-carboxylase activity in vitro. Plants supplied with 0.6 mM NO ₃ ^- show incomplete recovery of apparent quantum yield after 14 d, but CO₂-dependent leaf photosynthetic parameters return to control levels.Symbols and abbreviations F_o initial level of fluorescence at 77 K - F_m maximum level of fluorescence at 77 K - F_v variable components of fluorescence at 77 K (F_v=F_m-F_o) - PSI, PSII photosystem I and II, respectively - RuBP ribulose-1,5-bisphosphate - RuBPCase ribulose-1,5-bisphosphate carboxylase-oxygenase (EC 4.1.1.39)     

Vertebral pathology in the afar australopithecines

Ten vertebral elements from the AL-288 partial hominid skeleton and 11 elements from the AL-333 collection are described. The AL-288 column presents a marked kyphosis at the level of thoracic vertebrae 6 through 10, with pronounced new bone formation on the ventral surfaces of these vertebrae. These features, associated with narrowed disc space and minor osteophytosis, resemble Scheuermann disease in the human. Even though this diagnosis is consistent with a basically human, bipedal locomotor repertoire, the presence of Scheuermann disease suggests that lifting, climbing, or acrobatic activities may have been important in early hominids.     

Ultrastuctural and cytochemical study of spermatogenesis in Scrobicularia plana (Mollusca,Bivalvia)

The ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome-like junctions, elongated spermatids are held at the acrosomal region by support cell finger-like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 μm. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications.     

Nutrition et élevage du prédateur polyphageMacrolophus caliginosus [Heteroptera,Miridae] sur milieux artificiels

La possibilité de nourrir la punaiseMacrolophus caliginosus Wagner à l'aide de milieux artificiels a été testée. En l'absence de végétal, les témoins nourris avec des ?ufs d'Ephestia kuehniella Zeller ont une survie médiocre et fournisent 33% d'adultes. Avec le meilleur milieu artificiel la survie est comparable à celle des témoins et 21 % d'adultes sont obtenus. Avec ce même milieu, mais en présence de feuille de géranium, la production d'adultes atteint 62%. Les compositions en acides aminés des punaises élevées avec le milieu montrent des écarts inférieurs à 20% par rapport aux témoins. Le développement complet deM. caliginosus nourri à l'aide de milieu artificiel a été obtenu. Le végétal joue un rôle important dans la biologie de ce prédateur.     

Induction of c-fos mRNA Expression by Afterdischarge in the Hippocampus of Naive and Kindled Rats

Periodic induction of focal electrical seizure [afterdischarge (AD)] is an absolute prerequisite for the development of kindling, an animal model of complex partial epilepsy. Once established, it is a permanent condition. The mechanism(s) that translate ADs, which last tens of seconds, into life-long alterations in the CNS is unclear. Cellular immediate-early genes have been implicated in the conversion of short-term stimuli to long-term alterations in cellular phenotypes by regulating target gene expression. We have investigated the contribution of one such early gene, c-fos, to this process. The relationship between ADs and expression of c-fos gene in the rat hippocampus, a key structure in kindling development, was studied by analysis of mRNA levels. The low constitutive expression of c-fos mRNA in the hippocampus was not altered by kindling. There was an "all-or-none" relationship between induction of c-fos and the duration of AD. The threshold for induction was approximately 30 s of AD. Above-threshold ADs induced c-fos in both naive and kindled animals to the same extent and with identical temporal profiles. Although the expression of c-fos is unchanged with kindling, c-fos may nonetheless contribute to many long-term changes of kindling, both adaptive and epileptogenic.     

记内蒙古Juxia一新种

本文记述了在内蒙古沙拉木伦额尔登敖包地区第三系下渐新统乌兰戈楚组中发现的始巨犀的一个新种:寿氏始巨犀(Juxia shoui)。据其前臼齿及鼻切迹的位置等特点,这一新种当为始巨犀属中比较进步的一个成员,是包氏始巨犀和巨犀之间的过渡类型的犀类动物。     

陕西蓝田公王岭“蓝田伟猴”化石的再研究

蓝田公王岭动物群中,唯一的一种非人灵长类化石由胡长康、齐陶(1978)定名为Megamacaca lantianensis(蓝田伟猴)。但按其形态,我们觉得把它归于疣猴亚科比较适宜。特别是与该亚科中的金丝猴属(Rhinopithecus)更为相像,例如蓝田标本下颌支与下颌体垂直,冠状突略向后弯,齿尖起伏较大等都显示了金丝猴的一般性质。至此,本文将蓝田伟猴归于金丝猴属,保留原有种名:Rhinopithecus(Megamacaca)lantianensis(Hu and Qi)。时代为早更新世晚期。     

The effects of phosphate supply on growth of plants from the Brasilian Cerrado: experiments with seedlings of the annual weed,Bidens gardneri Baker (Compositeae) and the tree,Qualea grandiflora (Mart.) (Vochysiaceae)

Summary Plants of the cerrado tree species Qualea grandiflora and the annual herb Bidens gardneri were grown from seed in controlled environment rooms at 30/20° C and 12 hour photoperiod. Seedlings were grown in pots or small tubes containing sand and provided with various amounts of mineral solutions based on the formulation of Hoagland and Arnon but with the phosphate content modified in some cases. In a long-term experiment lasting 213 days, plants supplied with full strength Hoagland's solution all died but plants of Qualea given 1/10 strength solution survived, although they grew very slowly. Low relative growth rates (0.008–0.036 d^–1) were also a feature of other experiments with Qualea and calculated rates of net assimilation rate gave values of 3–7 mg CO₂ dm^–2 h^–1. Expansion of the photosynthetic surface proceeded slowly and the cotyledons were the main site of photosynthesis for more than 40 days. The low rates of growth occurred despite significant uptake of phosphorus by young plants and in shortterm experiments growth was independent of the amount of phosphate supplied and accumulated. In contrast, the values of R found for plants of Bidens reached 0.24 d^–1. Growth of young plants was dependent on the external supply of phosphorus, being reduced when this was low and also when it was very high. Growth of the photosynthetic surface was also much more rapid than for Qualea and also varied with supply of phosphorus. The results are discussed in the context of the occurrence of these species in the Cerrado.     

Threat calls in alliance formation by members of a captive group of Japanese monkeys

The vocal behavior of threat calls was investigated in a captive group of Japanese monkeys (Macaca fuscata fuscata). The vocalizations were heard most often when they undertook winner-support during triadic agonistic interactions. The likelihood of call emission in support of the winner was affected by the attributes of the participants, and not by the types of agonistic behavior. The calls were emitted by intermediate ranking animals frequently in support of high ranking animals and in support of females. The calling behavior of winner-supporters appears to advertise the partner and distant group members of their support for reciprocation in the near future.