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1.
Why Don't Chimpanzees in Gabon Crack Nuts?   总被引:5,自引:0,他引:5  
Some populations of wild chimpanzees (Pan troglodytes) use hammers and anvils of stone or wood to crack open nuts for food. Others do not. The aim of this study was to ask why one non-nut-cracking population, in the Lopé Reserve, Gabon, lacks this useful form of tool use. We tested 10 hypotheses: (1) nuts are absent; (2) nuts are few; (3) nuts are unsuitable; (4) hammers are absent; (5) hammers are unsuitable; (6) anvils are absent; (7) anvils are unsuitable; (8) nuts are displaced by better food items; (9) intelligence is insufficient; and (10) knowledge is insufficient. All but the last are clearly falsified, leaving by exclusion the likelihood that Lopé's chimpanzees lack the technology—knowledge of appropriate technique—to exploit this resource. Thus, the behavioral differences across populations of these apes are cultural and not environmentally dictated. This explanation is congruent with the distribution of chimpanzee nut-cracking across Africa.  相似文献   

2.
SYNOPSIS. Oocysts of Eimeria ambystomae Saxe, 1955, Eimeria microcapi sp. n., and Eimeria urodela sp. n. are described from the tiger salamander, Ambystoma tigrinum , collected in Colorado and New Mexico. The oocysts of E. ambystomae are ellipsoid, 29.8 × 17.3 (24–38 × 15–25) μm, and the sporocysts lanceolate, 22.6 × 5.4 (16–27 × 5–7) μm. Oocyst and sporocyst residua are present, but not a polar granule and a micropyle. The oocysts and sporocysts of E. microcapi are ellipsoid, measuring respectively 38.1 × 25.3 (35-41 × 23-26) μm and 18.1 × 7.4 (16-19 × 6–8) μm. Oocyst and sporocyst residua, a micropyle (mean 3 μm), and a distinct micropyle cap (2 μm high) are present, but not a polar granule. The oocysts of E. urodela are spheroid, 22.2 (14-26) μm, and the sporocysts lanceolate, 16.3 × 5.8 (12-19 × 4-7) μm. Oocyst and sporocyst residua are present, but a polar granule and a micropyle are absent.  相似文献   

3.
Stable conformations of β-isomaltose (α-d-glucopyranosyl-(1→6)-β-d-glucose) in gas-phase and aqueous solution are investigated in this study using quantum mechanical calculations. Conformational maps are calculated at HF/6-31G(d,p) level and lower energy structures are sampled in the most stable regions. Entropic and thermal corrections are considered and the Boltzmann population is obtained for conformers that are representative of the 18 most stable regions found on the potential energy surface. B3LYP/6-31+G(d,p) and B3LYP/6-311+G(2d,2p) calculations are used in conformational samplings. Solvation effects are considered through the polarizable continuum model approach. Hydroxymethyl group orientations are investigated for the most stable conformers. The influence of electronic correlation and solvation on the glycosidic linkage preference (TG, GT, and GG) and hydroxymethyl group orientation (tg, gt, and gg) are discussed. Heteronuclear spin coupling constants (3JC,H) along the glycosidic linkage are calculated and comparison with other theoretical results and experiments is used to validate the obtained structures.  相似文献   

4.
Summary An ultrastructual study of hemocytes from 9 different insect orders has led to the identification of 8 cell types: (1) Plasmatocytes, whose cytoplasm is filled with small dense lysosomes and large heterogeneous structures, are phagocytic cells. (2) Granulocytes, filled with uniformly electron dense granules, are involved in capsule formation. (3) Coagulocytes, which contain granules and structured globules and which possess a well developed RER, are involved in phagocytosis. (4) Spherule cells are filled with large spherical inclusions. (5) Oenocytoids are large cells with few cytoplasmic organelles. These 5 hemocyte types represent the majority of insect blood cells. (6) Prohemocytes, blastic cells which are one of the stem cells of hemocytes, are very few in number in each species investigated. (7) Thrombocytoids and (8) Prodocytes are restricted to a small number of insect species.The ultrastructural characteristics of these hemocyte types are discussed.  相似文献   

5.
The myobiid genus Acanthophthirius Perkins, to date comprising four subgenera, is reviewed and divided into just two subgenera, the nominate subgenus and Myotimyobia Fain. The male genital shield and female opisthogastric sclerites, which are here considered to be part of female genitalia, are adopted as the criteria for dividing the subgenera. These structures are essentially the same in form and position in the subgenus Acanthopthirius in its revised sense, while they are both more heterogeneous in species of the redefined subgenus Myotimyobia. The subgenera Acanthophthirius Fain and Chiromyobia Fain are thought to represent species-groups in the nominate subgenus, named respectively the etheldredae and miniopteri groups. The following one new subspecies and 11 new species are described: A. (A.) womersleyi eptesicus, A. (A.) glauconycteris, A. (A.) mauritaniensis, A. (A.) philetoris, A. (A.) otonycteris, A. (A.) steatocaudatus, A. (A.) nyctophilis, A. (M.) vagus, A. (M.) longus A. (M.) baueris, A. (A.) hesperopteris (female only) and A. (M.) pixonixeos (female only). A. (M.) hanensis is synonymised with A. (M.) namurensis, and A. (M.) capacini is emended to A. (M.) capaccinii and relegated to a subspecies of A. (M.) myotis. All the known and new species are assigned to their respective subgenera and shown in a table. Incongruent host-relationships of some of the mites are clarified, although not completely solved, by the introduction of the new classification for the subgenera.  相似文献   

6.
Three new species of Oriental Perlini are described and Agnetina aequalis (Banks) and A. quadrituberculata (Wu) are redescribed. Agnetina jarai sp. n. (Vietnam), Togoperla shan sp. n. (Thailand), and Tyloperla schmidi sp. n. (Assam), are described, compared with related congeners, and male holotypes are designated for each species.  相似文献   

7.
Two gastropod assemblages from the Carnian (Upper Triassic) Raibl Beds of the Mežica region (Karavanke Mountains, Slovenia) are described. The almost monospecific, older assemblage from Mežica Mine was found as a thin shell pavement in the clastic sequence. This association apparently originated during a period of reduced sedimentation. The younger assemblage from Helena Creek was found at the upper surface of an oolitic and oncoidal limestone and represents a more diversified fauna of a crinoid/coelenterate/polychaete meadow. Together, both assemblages contain 11 gastropod species. Five of them are left in open nomenclature, two are known from other localities in the Alps, and the remaining four are new. The new species are Sloeudaronia karavankensis (Skeneidae), Helenostylina mezicaensis (Coelostylinidae), Ampezzopleura slovenica and Striazyga crnaensis (Zygopleuridae). Two new genera, Sloeudaronia (Skeneidae) and Helenostylina (Coelostylinidae), are described.An erratum to this article can be found at  相似文献   

8.
Human African trypanosomiasis (HAT) is an important public health threat in sub-Saharan Africa. Current drugs are unsatisfactory, and new drugs are being sought. Few validated enzyme targets are available to support drug discovery efforts, so our goal was to obtain essentiality data on genes with proven utility as drug targets. Aminoacyl-tRNA synthetases (aaRSs) are known drug targets for bacterial and fungal pathogens and are required for protein synthesis. Here we survey the essentiality of eight Trypanosoma brucei aaRSs by RNA interference (RNAi) gene expression knockdown, covering an enzyme from each major aaRS class: valyl-tRNA synthetase (ValRS) (class Ia), tryptophanyl-tRNA synthetase (TrpRS-1) (class Ib), arginyl-tRNA synthetase (ArgRS) (class Ic), glutamyl-tRNA synthetase (GluRS) (class 1c), threonyl-tRNA synthetase (ThrRS) (class IIa), asparaginyl-tRNA synthetase (AsnRS) (class IIb), and phenylalanyl-tRNA synthetase (α and β) (PheRS) (class IIc). Knockdown of mRNA encoding these enzymes in T. brucei mammalian stage parasites showed that all were essential for parasite growth and survival in vitro. The reduced expression resulted in growth, morphological, cell cycle, and DNA content abnormalities. ThrRS was characterized in greater detail, showing that the purified recombinant enzyme displayed ThrRS activity and that the protein localized to both the cytosol and mitochondrion. Borrelidin, a known inhibitor of ThrRS, was an inhibitor of T. brucei ThrRS and showed antitrypanosomal activity. The data show that aaRSs are essential for T. brucei survival and are likely to be excellent targets for drug discovery efforts.  相似文献   

9.
Biliary excretion in foreign compounds. Sulphonamide drugs in the rat   总被引:14,自引:13,他引:1       下载免费PDF全文
1. The extent of biliary excretion in the rat of 15 sulphonamide compounds was studied. 2. Most of the sulphonamides studied, with molecular weights from 172 (sulphanilamide) to 352 (N4-acetylsulphadimethoxine) are poorly excreted in the bile (0–4% of the dose), except sulphapyridine, sulphamethoxypyridazine and sulphadimethoxine. The last three are partly metabolized to glucuronides, whose molecular weights and polarities are such as to allow them to be excreted in the bile in appreciable amounts. 3. Succinylsulphathiazole and phthalylsulphathiazole are polar and have molecular weights (355 and 403) of an appropriate order, and are excreted unchanged in the bile in appreciable amounts. 4. Sulphadimethoxine N1-glucuronide (mol.wt. 487) is extensively excreted in the bile unchanged. 5. The results are examined in the light of the hypotheses put forward in the preceding paper (Millburn, Smith & Williams, 1967).  相似文献   

10.
Malus sieversii is a progenitor species of domestic apple M. × domestica. Using population “GMAL 4595” of 188 individuals derived from a cross of Royal Gala × PI 613988 (apple scab resistant, M. sieversii), 287 SSR (simple sequence repeats) loci were mapped. Of these SSRs, 80 are published anchors and 207 are newly developed EST (expressed sequence tag) contig-based SSRs, representing 1,630 Malus EST accessions in GenBank. Putative gene functions of these EST contigs are diverse, including regulating plant growth, development and response to environmental stresses. Among the 80 published SSRs, 18 are PI 613988 specific, 38 are common and 24 are Royal Gala specific. Out of the 207 newly developed EST contig-based SSRs, 79 are PI 613988 specific, 45 are common and 83 are Royal Gala specific. These results led to the construction of a M. sieversii map (1,387.0 cM) of 180 SSR markers and a Royal Gala map (1,283.4 cM) of 190 SSR markers. Mapping of scab resistance was independently conducted in two subsets of population “GMAL 4595” that were inoculated with Ventura inaequalis races (1) and (2), respectively. In combination with the two major resistance reactions Chl (chlorotic lesions) and SN (stellate necrosis) to each race, four subsets of resistance data, i.e., Chl/race (1), SN/race (1), Chl/race (2) and SN/race (2), were constituted and analyzed, leading to four resistance loci mapped to the linkage group 2 of PI 613988; SNR1 (stellate necrosis resistance to race (1)) and SNR2 are tightly linked in a region of known scab resistance genes, and ChlR1 (Chlorotic lesion resistance to race (1)) and ChlR2 are also linked tightly but in a region without known scab resistance genes. The utility of the two linkage maps, the new EST contig-based markers and M. sieversii as sources of apple scab resistance are discussed.  相似文献   

11.
Inland salt waters of southern Africa   总被引:5,自引:5,他引:0  
Inland salt lakes are widely distributed in southern Africa: they are particularly common in South Africa, but many occur in Namibia and Botswana. All are shallow, and most are ephemeral with salinities that are not very high (mostly < 50 g l−1). Fringing zones of halophytes or submerged macrophytes are neither well-developed nor taxonomically diverse. The Cyanobacteria, especially Nodularia spumigena, often dominate the phytoplankton. The fauna of the Makgadikgadi area (northeast Botswana) is diverse and is similar to that of East African salt lakes. The aquatic fauna of salt water south of the Makgadikgadi Basin, on the other hand, is extremely depauperate, has no well-defined assemblage confined to saline waters, and appears mostly to comprise tolerant freshwater forms. Lovenula falcifera and Metadiaptomus transvaalensis (diaptomid copepods), Moina micrura (Cladocera) and Brachionus plicatilis (Rotifera) are frequently encountered zooplankton species, a few species of insects (Anisops sp., beetles, chironomids and ephydrids) are the principal non-planktonic macroinvertebrates. Artemia ‘salina’ is occasionally present, but may be an introduced form. The avifauna, in contrast to the aquatic macroinvertebrate fauna, is rich, with the greater and lesser flamingo often common.  相似文献   

12.
Analyses of meiotic and mitotic chromosomes were undertaken in 16 taxa of Echinocereus belonging to 12 species and all seven taxonomic sections (sensu Taylor). Chromosome numbers are reported for the first time for eight taxa, and previously published chromosome counts are confirmed for the remaining eight. Both diploid and polyploid counts were obtained. Eleven (69%) of the taxa surveyed were diploid (2n = 22); the five varieties of E. engelmannii were polyploid (2n = 44). Overall, chromosome counts are available for 23 of the 48 proposed species (sensu Taylor). Of these, 19 (82%) are diploid, and four (18%) are polyploid. Polyploid cytotypes are most common in the primitive sections, e.g., sections Erecti and Triglochidiatus, which suggests that polyploidy is probably a derived condition in Echinocereus. Polyploid taxa range from medium to high latitudes and elevations relative to the overall distribution of the genus. Polyploidy, hybridization, and cryptic chromosomal rearrangements are thought to be the major causes of the speciation events of the genus.  相似文献   

13.
SYNOPSIS Four new eimerian species are described from red-backed voles. Clethrionomys gapperi in Pennsylvania. Sporulated oocysts of Eimeria clethrionomyis sp. n. are ellipsoidal, 18.8 (16.5–21.5) × 14.9 (14.0–16.5) with elongate, ovoid sporocysts, 10.6 (9.5–12.0) × 6.1 (5.5–7.0). The oocyst wall is smooth, with 2 layers, and thins, with terminal cap at one or both ends. Polar granules, dark Stieda body and sporocyst residuum are present. The occyst residuum is absent. Sporulated oocysts of Eimeria gallatii sp. n. are ellipsoidal, 27.7 (21–32) × 19.3 (17–24) with ovoid sporocysts, 13.5 (12–15) × 8.8 (8–10). The oocyst wall is smooth, 2-layered, with a micropyle and thin wall at the end opposite the micropyle. Polar granules. Stieda body and sporocyst residuum are present. The oocyst residuum is atypical, of cobwebby material. Sporulated oocysts of Eimeria pileata sp. n. are subspherical to spherical, 25.2 (20.5–29.5) × 22.5(19.5–25.5) with ellipsoidal sporocysts, 13.4(10.5–15.0) × 8.4 (7.5–9.5). The oocyst wall is rough, pitted, striated, 2-layered, with no micropyle. Polar granules, oocyst and sporocyst residuum. Stieda body and stiedal cap are present. Sporulated oocysts of Eimeria marconii sp. n. are ellipsoidal, 13.0 (10.5–15.0) × 10.6 (9.5–12.0) with elongate, ovoid sporocysts, 7.7 (7.0–8.5) × 4.2 (3.0–4.5). The oocyst wall is smooth, single-layered, with no micropyle. Polar granules, dark Stieda body and sporocyst residuum are present. There is no oocyst residuum.  相似文献   

14.
Twenty-two pteridophytes (13 endemic and 9 non-endemic) from São Tomé e Príncipe (Gulf of Guinea) are evaluated as regards their rarity and conservation status. IUCN Red List Categories are assigned to these taxa. Eight taxa are Critically Endangered (CR), eleven taxa are Vulnerable (VU) and three taxa are Endangered (EN). Specific measures to conserve these rare pteridophytes are outlined.  相似文献   

15.
Efficient degradation of by‐products of protein biogenesis maintains cellular fitness. Strikingly, the major biosynthetic compartment in eukaryotic cells, the endoplasmic reticulum (ER), lacks degradative machineries. Misfolded proteins in the ER are translocated to the cytosol for proteasomal degradation via ER‐associated degradation (ERAD). Alternatively, they are segregated in ER subdomains that are shed from the biosynthetic compartment and are delivered to endolysosomes under control of ER‐phagy receptors for ER‐to‐lysosome‐associated degradation (ERLAD). Demannosylation of N‐linked oligosaccharides targets terminally misfolded proteins for ERAD. How misfolded proteins are eventually marked for ERLAD is not known. Here, we show for ATZ and mutant Pro‐collagen that cycles of de‐/re‐glucosylation of selected N‐glycans and persistent association with Calnexin (CNX) are required and sufficient to mark ERAD‐resistant misfolded proteins for FAM134B‐driven lysosomal delivery. In summary, we show that mannose and glucose processing of N‐glycans are triggering events that target misfolded proteins in the ER to proteasomal (ERAD) and lysosomal (ERLAD) clearance, respectively, regulating protein quality control in eukaryotic cells.  相似文献   

16.
Abstract

In the present paper 702 families have been studied belonging to different endogamous groups in three multicaste villages of Srikakulam District, Andhra Pradesh. It is observed that 33.76 per cent of families are consanguineous marriages. With regard to the types of marriages, 12.11 per cent are uncle‐niece; 14.10 per cent are matrilateral cross‐cousins; 5.84 per cent are patrilateral cross‐cousins; 0.57 per cent are first cousins once removed, and 1.14 per cent are second cousins. There are only six couples (0.86 per cent) in intercaste marriages. The coefficient of inbreeding for autosomal and sex‐linked genes, 0.045 and 0.059, respectively, for Chakalis which are higher than Kalingas (F = 0.03; F1 = 0.038), Segidis (F = 0.031; F1 = 0.041), Velamas (F = 0.026; F1 = 0.036), Vysyas (F = 0.027; F1 = 0.034), Malas (F = 0.017; F1 = 0.026), and others (F = 0.026; F1 = 0.032). The t‐tests for mean marriage distances are statistically significant among all castes, but chi‐squares for intergroup difference of consanguineous and nonconsanguineous marriages are statistically significant only among Kalingas and Chakalis, Vysyas and Chakalis, and Malas and Chakalis.  相似文献   

17.
World species of the genus Archipines are reviewed, keyed and illustrated. The following new synonyms are proposed: Archipines championi (Gorham, 1889) [=Archipines multinotata (Pic, 1929)]; Archipines exsanguis (Gerstaecker, 1858) [=Archipines quadrimaculata (Pic, 1928)]; Archipines flavida (Pic, 1928) [=Archipines grandis Strohecker, 1957]. Lectotypes are designated for Phalantha championi Gorham, Ph. intricata Gorham, Ph. pictipennis Gorham and Ph. variegata Gorham. Four new species: Archipines oberthuri (Brazil), A. unicolor (Brazil), A. macromaculata (Peru), A. peruviensis (Peru) and two new subspecies: A. exsanguis sanestebani (Venezuela), A. apicicornis fairmairei (Peru) are described. The immature stages (mature larva and pupa) of A. championi are described and illustrated. Distribution, nomenclatural history and diagnoses are provided for each species.  相似文献   

18.
This paper describes three new species of Isospora from Pycnonotus 1eucogenys in Saudi Arabia ( I. gatifenensis sp.n.; I. khobarensis sp.n. and I. hafoufenensis sp.n.). Sporulated oocyats of I. gatifenensis are ovoidal, 23-26.5 ± 16.5-19(25.03 ± 0.12 ± 18.13 ± 0.09))μm and sporocysts are elongated ovoidal 17-20.5 ± 8-11 (18.9 ± 0.09 ± 9.3 ± 0.07) μm. Sporulated oocysts of I. khobarensis are ovoidal 22-26 ± 15.5-19 (24.3 ± 0.18 ± 17.1 ± 0.19)μm and sporocysts are pyriform 13-16 ± 9-11.5 (14.8 ± 0.15 ± 9.9 ± 0.13)μm. Sporulated oocysts of I. hafoufenensis are ovoidal 22-27 ± 19-24(25.4 ± 0.25 ± 22.1 ± 0.26) μm and sporocysts are ovoidal 14.5-18 ± 8-13 (16.5 ± 0.14 ± 11.4 ± 0.18) μm.  相似文献   

19.
Lorilichus n. g. (Pterolichidae, Pterolichinae) is restricted to the Indo-Australian parrots of the family Loriidae. Assigned to this new genus are Pterolichus (Pseudalloptes) species described by Trouessart in 1884, namely, lobiger (type-species), delibativentris, discifer, cultriventris, emargiventris and securiventris. The first three named species are illustrated and two new species, parvifolius and grandifolius, are described: the five species are from Lorius domicellus (L.).  相似文献   

20.
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