Herbivorous insect species in the tree canopy of a relict South African forest

Abstract.

• 1 The herbivorous insects on twelve species of evergreen broadleafed trees were repeatedly sampled over a period of 11 months in a small relict forest on the east coast of South Africa. This extraordinarily speciose forest patch has an unusually high proportion of endemic tree species, some of which are extremely rare.
• 2 The insect herbivore fauna (number of species) seems to be markedly depauperate compared to that reported on native, broadleafed trees from other parts of the world. Some possible reasons for this are discussed.
• 3 The total number of herbivorous insect species on each tree species was strongly correlated with the local relative abundance of the host plant species.
• 4 There was no relationship between the total number of insect herbivore species on each tree species and the relative taxonomic isolation of the trees. The proportion of seemingly unique (= specialist) herbivorous insect species (i.e. those that occurred on one tree species only) was greatest on taxonomically isolated trees.
• 5 A fundamental deficiency in the interpretation of the data in this study, and of many other similar studies that report on the number of insect species on plants, is discussed, namely the lack of clarity on the closeness of the association between individual insect herbivore species and their respective host plants.

     

Isolation of humic acid from the brown algaPilayella littoralis

A standard humic acid extraction procedure has been used to isolate dark brown organic residues from samples of the macroscopic marine brown algaPilayella littoralis. The residues are insoluble in water, but soluble at high pH, and are similar in elemental composition, ash content, UV-visible, IR, PMR and X-Ray fluorescence spectra, X-Ray diffractograms and scanning electron micrographs to residues of a humic acid isolated from municipal compost. These results indicate thatPilayella produces humic acids.Author for correspondence     

金属螯合亲和层析纯化金属硫蛋白

将二价铜离子螯合在Chelating Sepharose Fast Flow凝胶上制成亲和层析柱,锌诱导兔肝和镉诱导小鼠肝经匀浆、乙醇处理后上柱,用pH4.0的醋酸盐缓冲液平衡,再用pH5.2不同浓度的醋酸盐缓冲液分别洗脱,可得两个金属硫蛋白(MT)洗脱峰,经确定先后为MT-2和MT-1.分离方法比传统的凝胶过滤-离子交换法简单、省时,适于实验室规模分离纯化.     

Two related,low-temperature-induced genes from Brassica napus are homologous to the human tumour bbc1 (breast basic conserved) gene

In order to identify genes involved in cold acclimation, we have constructed a cDNA library from Brassica napus (cv. Samouraï) cold-acclimated etiolated seedlings. By differential screening, a cDNA clone named pBnC24 (Brassica napus Cold), corresponding to a new cold-inducible plant gene, was isolated. Northern blot hybridizations using total RNA from acclimated and unacclimated seedlings confirmed that BnC24 represents a cold-regulated gene. In contrast with a number of cold-inducible plant genes, BnC24 does not seem to be responsive to abscisic acid (ABA). In addition, further screening of the cold-acclimated cDNA library using pBnC24 cDNA as a probe, allowed the isolation of a second type of homologous cDNA. Sequence analysis showed that the two BnC24 genes encode basic 24 kDa proteins, which are highly hydrophilic and rich in alanine, lysine and arginine. The nucleotide and deduced amino acid sequences of these clones do not show any homology with other previously described cold-induced plants genes. However they have strong homology with a recently discovered human tumour gene, bbc1 (breast basic conserved), which seems to be highly conserved in eukaryotes.     

Molecular characterization of salt-stress-associated protein in citrus: protein and cDNA sequence homology to mammalian glutathione peroxidases

A gene encoding for a citrus salt-stress-associated protein (Cit-SAP) was cloned from Citrus sinensis salt-treated cell suspension. The gene, designated csa, was isolated from a cDNA expression library. The partial amino acid sequence of the protein, as well as that deduced from the nucleotide sequence of csa, revealed a considerable homology to mammalian glutathione peroxidase (GP), and to clone 6P229 from tobacco protoplasts. The increased expression of Cit-SAP in NaCl-treated cultured citrus cells and in citrus plants irrigated with saline water, and its similarity to GP, raise the possibility that one of the effects of salt stress in plants may be the increase of the level of free radicals.     

The Casparian Strip of Clivia miniata Reg. Roots: Isolation,Fine Structure and Chemical Nature*

The root endodermis of Clivia miniata Reg. was successfully isolated using the cell wall degrading enzymes cellulase and pectinase. The enzymes did not depolymerize those regions of the primary cell walls of anticlinal endodermal root cells where the Casparian strips were located. Since the endodermis of C. miniata roots remained in its primary developmental state over the whole root length, endodermal isolates essentially represented Casparian strips. Thus, sufficient amounts of isolated Casparian strips could be obtained to allow further detailed investigations of the isolates by microscopic, histochemical and analytical methods. Scanning electron microscopy revealed the reticular structure of the Casparian strips completely surrounding the central cylinder of the roots. Whereas in younger parts of the root only the anticlinal cell walls of the endodermis remained intact in the isolates, in older parts of the root the periclinal walls also restricted enzymatic degradation due to the deposition of lignin. Extracts of the isolates with organic solvents did not reveal any wax-like substances which might have been deposited within the cell wall forming a transport barrier, as is the case with cutin and suberin. However, several histochemical and analytical methods (elemental analysis and FTIR spectroscopy) showed that the chemical nature of the Casparian strips of C. miniata roots can definitely be a lignified cell wall. These findings are in complete agreement with studies carried out at the beginning of this century on the chemical nature of the Casparian strips of several other plant species. The implications of these results concerning apoplasmatic transport of solutes and water across Casparian strips are discussed.     

从一名国内感染的艾滋病人分离人免疫缺陷病毒（HIV）

从一名国内感染的艾滋病人采血,分离其外周血单核细胞（ＰＭＣｓ）。首先与正常的ＰＭＣｓ共培养,４周后检测其ＨＩＶ－１ｐ２４抗原（ＥＬＩＳＡ）达到峰值。用此时的细胞及其上清分别感染Ｊｕｒｋａｔ－ｔａｔ、ＣＥＭ、ＭＴ４细胞,可很快地在这三株细胞中检测到ＨＩＶ生长,ＨＩＶ在Ｊｕｒｋａｔ－ｔａｔ细胞中生长情况最好,同时用病人血清直接感染Ｊｕｒｋａｔ－ｔａｔ和ＭＴ４细胞,４周后检测其细胞上清ＨＩＶ－１ｐ２４抗原（ＥＬＩＳＡ法）为阳性,但ＯＤ值很低（约为ＰＭＣ共培养组的一半）。用病人的少量全血与正常ＰＭＣｓ共培养,得到的结果与分离病人ＰＭＣｓ法相近。应用间接免疫荧光法（ＩＦＡ）、免疫酶法（ＩＥＡ）、蛋白印迹法及ＨＩＶ－１ＰＯｌ基因和Ｅｎｖ基因特异引物的聚合酶链反应（ＰＣＲ）等证实为ＨＩＶ－１病毒。分离的ＨＩＶ在Ｊｕｒｋａｔ－ｔａｔ细胞中连续传代,细胞被感染后２－３天即出现以大量融合细胞为主的细胞病变,感染后７－１０天细胞几乎全部死亡。病毒在连续传代过程中的生长特征及致细胞病变特征不变。此病毒命名为ＣＡ－２毒株。     

Sexual isolation in Drosophila. II. Intraspecific variation in mate recognition systems

A simple behavioral model is used to investigate whether differences in the specific-mate-recognition system (SMRS), occur within species of the Drosophila genus. This model takes into account, and overcomes, the distorting effect of vigor differences on experimental results. Analysis shows significant deviations from the expected values under the assumption of identical SMRSs in around one fifth of the multiple-choice experiments performed with natural strains of twelve different Drosophila species. Different selection procedures raise the number of significant assortative mating results between strains of D. melanogaster and D. pseudoobscura from 3.0% to 32.8%. Finally, sub- or semispecific taxa show variations in their SMRS even more frequently (74.5%). Differences in male vigor and female receptivity are also found. These results show that a classification of Drosophila species based on SMRS stability, as proposed by the “Recognition concept of species”, is virtually impossible.     

Substance P-Evoked Calcium Mobilization and Ionic Current Activation in the Human Astrocytoma Cell Line U 373 MG: Pharmacological Characterization

Abstract— In the human astrocytoma cell line U 373 MG, application of substance P (SP) leads to a transient increase in cytosolic calcium concentration and to a biphasic current response in voltage-clamped cells. Using these two functional assays we have characterized pharmacologically the SP response in U 373 MG cells. SP and [l -Pro⁹]SP displayed high potencies in both assays with EC₅₀values of 2.5 ± 10^?9M and 1 ± 10^?9M on calcium responses and 110^?9M and 510^?9M on ion current responses, respectively. The high potency of SP and [l -Pro⁹]SP as well as the low potency of [Lys⁵,MeLeu⁹,N-Leu¹⁰]neurokinin A_(4-10) and the inactivity of senktide demonstrate the NK₁-type pharmacology of these responses. Furthermore, the NK₁ antagonists (±)-CP 96,345, its chloro analogue, (±)-cis-3-(2-chlorobenzylamino)-2-benz-hydrylquinuclidine, and RP 67580 were potent antagonists of both SP responses. For the calcium mobilization induced by SP (1 (10^?7M), the IC₅₀ values for the three antagonists were 4 ± 10^?10M, 4 ± 10^?9M, and 9 ± 10^?9M, respectively, whereas on the current response evoked by SP 10^?8M), the IC₅₀ values were 8 ± 10^?9M, 2.4 ± 10^?8M, and 1.2 10^?7M, respectively. Despite differences in the absolute IC₅₀ values obtained with both techniques, the relative potencies of the three antagonists correlate fairly well. The U 373 MG cell line provides a useful model system for studies of the pharmacology of the human NK₁receptor and its transduction mechanisms at the level of second messengers and modulation of ion currents.     

THE GENETICS OF AN ISOLATING MECHANISM BETWEEN TWO SIBLING SPECIES OF DROSOPHILA

Matings between Drosophila simulans females and males of the sibling species D. mauritiana are of abnormally short duration. These rapid matings interrupt the transfer of sperm, leading to substantial reproductive isolation in interspecific as compared to intraspecific copulations. Genetic analysis of this behavior shows that it is influenced much more by the male than the female genotype, with genes from D. simulans being dominant. In males, shortened copulation is caused by interspecific divergence at a minimum of three loci, with one gene on each of the major chromosomes. This is an underestimate of the true number of loci affecting the trait, which could be much larger. The two autosomes have the largest effect, whereas that of the X chromosome is much smaller. The genetic architecture of copulation duration and the larger effect of male than female genotype suggest that females can detect and discriminate against differences in male genitalia.