Fate of sperm tail components after incorporation into the hamster egg

The changes in the cytoplasmic organelles of sperm tail in golden hamster eggs fertilized in vivo were observed by electron microscopy. Eggs were obtained from oviducts of hamsters that had been superovulated and inseminated by injection of cauda epididymal spermatozoa into the uteri. In the egg cytoplasm 10 hours after insemination, some of the mitochondria of the spermatozoon midpiece had begun to swell, and a number of multivesicular bodies were observed surrounding the midpiece. The fibrous sheath of the principal piece quickly disappeared prior to the first cleavage, whereas the axoneme and outer dense fibers were unaltered. During the two-cell stage, numerous multivesicular bodies gathered around the midpiece and fused with the mitochondria. The heterophagic vacuoles thus formed then gradually separated from the axial fibers. The outer dense fibers were disarranged and partially torn into small segments; then they seemed to dissociate into substructural granular components. The axonemal microtubules had begun to swell but were still present in the two blastomeres. It is indicated from these observations that at least the mitochondria of the tail constituents carried into the oocyte are digested into small molecular elements by the multivesicular bodies and are possibly distributed as nutrients for the blastomeres during the early stage of development.     

The structure and phenology of a moist deciduous forest in the Central Indian Highlands

The vegetation structure and phenology of a 74.5 ha block of moist deeiduous forest in Kanha Tiger Reserve, Madhya Pradesh, India were investigated during primatological fieldwork. Within a grid of 0.25 ha quadrats all 9935 trees (woody plants > 2 m tall), of 63 species, were enumerated and their girth measured. The forest was dominated by the dipterocarp sal (Shorea robusta). Most species were rare and showed clumped distributions within the sea of sal whilst the dispersion of five large canopy trees could not be distinguished from random.The phenology of 215 trees, of 61 species, was monitored over 14 months using an index of phytophase abundance. Leaf renewal was highly synchronous between and within species, mostly occurring between February and June. One species was evergreen, 5 were semi-evergreen and 55 were deciduous. Flowering generally occurred between leaf fall and flush whilst fruiting peaked late in the hot weather and early monsoon.     

Structure and floristic composition of the lowland rain forest of Los Tuxtlas,Mexico

Physiognomy, structure and floristic composition of one hectare of lowland tropical rain forest was studied in detail at Los Tuxtlas, Mexico. Physiognomically, the Los Tuxtlas forest should be classified as lowland tropical high evergreen rain forest. The forest showed a closed canopy at 30–35 m. Of all woody, non-climbing species with a DBH1.0 cm 89.4% (94.5% of all individuals) were evergreen, 25.4% (59.5% of the individuals) had compound leaves, and over 80% of species (and individuals) had leaves in the notophyll and mesophyll size classes. The forest structure was characterized by a low density (2976 individuals with a DBH1.0 cm, 346 individuals with a DBH10.0 cm, per ha, excluding vines) with an average basal area (38.1 m², DBH1.0 cm, 34.9 m², DBH10.0 cm, per ha, excluding vines). This was attributed to the relative maturity of the forest on the study plot. The study plot contained 234 species (11 208 individuals with a height 0.5 m), of which 55.1% (34.8% of individuals) were trees, 9.4% (6.8%) shrubs, 3.4% (44.3%) palms, 20.1% (5.2%) vines, 6.8% (8.7%) herbs and 5.1% (0.3%) of unknown lifeform. Furthermore, 58 species of epiphytes and hemi-epiphytes were found. Diversity of trees, shrubs and palms with a DBH1.0 cm was calculated as Shannon-Wiener index (4.65), Equitability index (0.65), and Simpson index (0.10). The dominance-diversity curve showed a lognormal form, characteristic for tropical rain forest. The community structure was characterized by a relative dominance of Astrocaryum mexicanum in the understorey, Pseudolmedia oxyphyllaria in the middle storeys, and Nectandra ambigens in the canopy. Species population structures of 31 species showed three characteristic patterns, differentiated by recruitment: continuously high, discontinuously high, and continuously low recruitment. Height/diameter and crown cover/diameter diagrams suggested a very gradual shift from height growth to crown growth during tree development. Forest turnover was calculated as 138 years. Compared to other tropical rain forests the Los Tuxtlas forest had 1. similar leaf physiognomical characteristics, 2. a lower diversity, 3. a lower density, 4. an average basal area, and 5. a slow canopy turnover.     

Rainbow trout (Oncorhynchus mykiss) neuropeptide Y.

Neuropeptide Y (NPY) has been isolated from brain extracts of the rainbow trout (Oncorhynchus mykiss) and subjected to structural analyses. Plasma desorption mass spectroscopy estimated the molecular mass of the purified peptide as 4303.9 Da. Automated Edman degradation unequivocally established the sequence of a 36 amino acid residue peptide as: Tyr-Pro-Pro-Lys-Pro-Glu-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Pro-Glu-Glu-Leu-Ala-Lys-Tyr-Tyr-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr. The molecular mass calculated from this sequence (4304 Da) is consistent with that obtained by mass spectroscopy. The presence of a C-terminal amide was established by radioimmunoassay. Rainbow trout NPY is identical in primary structure to coho salmon (Oncorhynchus kisutch) pancreatic polypeptide (PP). These data may indicate that, in this group of salmonid fishes, a single member of the NPY/PP peptide family is expressed in both neurons and peripheral endocrine cells.     

Morphological dispersion of introduced Hawaiian finches: evidence for competition and a Narcissus effect

Summary Morphological analyses were conducted on finch species introduced to Oahu, Hawaii. As many as 25 species of finches representing four families (Emberizidae, Fringillidae, Ploecidae, Estrildidae) have been introduced to Oahu. Of these, 15 species currently have established wild populations. When compared with pools of 25 and 23 species introduced to Oahu, the 15 surviving species are morphologically overdispersed. This result is consistent with the hypothesis that competition has influenced the outcome of these introductions. We also tested the hypothesis that surviving introduced finches in one habitat (sugarcane fields) were morphologically overdispersed. When the seven surviving finch species found in sugarcane were compared with the pools of 25 and 23 species, they too were morphologically overdispersed. However, when the seven sugarcane species were compared with a species pool consisting of only the surviving 15 species found across Oahu, they were not morphologically overdispersed. This result suggests that morphological analyses of community structure based only on comparisons of assemblages of surviving species may be biased by a Narcissus effect.     

Structure of the sugar-phosphate moiety of lipid A from lipooligosaccharide of Neisseria meningitidis group B,strain BC5S No. 125

On the basis of chemical and NMR data the partial structure of lipid A from lipooligosaccharide (LOS) of Neisseria meningitidis group B, strain BC₅S No 125 was established. Lipid A consisted of disaccharide 2-deoxy-6-O-[2-deoxy-2-(3-hydroxytetradecanoylamino)--gluco-pyranosyl]-2-(3-hydroxytetradecanoylamino)--glucopyranose carrying the -(2-aminoethyl)pyrophosphate residue at 0–4 and the pyrophosphate or phosphate residue at 0–1. On hydrolysis of the acidic form of LOS with 1% acetic acid the substituent at 0–1 was practically completely removed whereas that at 0–4 was stable. The analogous hydrolysis of the Mg-salt of LOS was accompanied by splitting off the pyrophosphate linkage in the substituent at 0–4. Hydrolysis of LOS at pH 4.5 in the presence of SDS led mainly to a lipid A preparation retaining both pyrophosphate residues.Abbreviations KDO 2-keto-3-deoxyoctulosonic acid - LA-I, LA-II preparations of lipid A - LOS lipooligosaccharide - LOS-H⁺ the acidic form of LOS - OS oligosaccharide - TLC thin-layer chromatography - GLC-MS gas-liquid chromatography/mass spectrometry     

Structural characterization of lipid A component of Erwinia carotovora lipopolysaccharide

The chemical structure of the lipid A component of lipopolysaccharide excreted into the liquid medium by the plant pathogenic enterobacterium Erwinia carotovora FERM P-7576 was characterized. It consists of a -1, 6-linked glucosamine disaccharide which carries ester-and amide-bound fatty acids and phosphate similar to the lipid A from other gram-negative bacteria. The lipid A preparation was not uniform in the number and composition of the fatty acids linked to the disaccharide. Four prominent lipids A were involved, they were composed of five to seven residues of fatty acid. Among them the major component was hexa-acyl lipid A, in which the hydroxyl group at position 3 and the amino group of the non-reducing glucosamine unit carry 3-dodecanoyl-oxytetradecanoyl residues. Positions 2 and 3 of the reducing glucosamine unit were substituted by 3-hydroxytetradecanoic acid. In the hepta-acyl lipid A, an additional hexadecanoic acid was linked to the hydroxyl group of the 3-hydroxytetradecanoyl residue at position 2 of the hexa-acyl lipid A. Two penta-acyl lipids A were the homologs of the hexa-acyl lipid A with decreasing acylation. Dodecanoic acid was missing from one, and 3-hydroxytetradecanoic acid from another. 3-Dodecanoyloxytetradecanoyl residue at position 3 differentiates E. carotovora lipid A from that of other gram-negative bacteria.Abbreviations LPS lipopolysaccharide - GlcN glucosamine - KDO 3-deoxy-d-manno-octulosonic acid - FAB-MS fast atom bombardment mass spectrometry - u atomic mass unit     

Geminiviruses: Genome structure and gene function

The plant pathogenic single‐strand DNA‐containing geminiviruses have been the recent focus of intense investigation, owing both to their agronomic importance and to their potential as vectors for the expression of foreign genes in plants. Molecular genetic studies have provided detailed information on the genomic organization of many of these viruses. A greater genetic complexity has been demonstrated among the members of this viral family than had previously been suspected, as well as an apparently rapid rate of evolution of genetic diversity. We now recognize fundamental differences in the genome structure and organization of the whitefly‐ and leafhopper‐transmitted viruses, as well as among those geminiviruses infecting dicotyledonous or monocotyledonous hosts. This knowledge has provided new insights into the evolution of these viruses. The viral genes involved in replication and in systemic movement in the plant have been defined, and viral origins for single‐strand (ss) and double‐strand (ds) DNA replication have been mapped to small nucleotide regions. With the structural features of the viral genomes now well defined, current efforts are focused on elucidating the molecular aspects of viral gene regulation and interactions with host‐cell components that lead to the production of disease. Recent progress in determining the mechanism of replication and systemic movement and the contributions of these to symptom and disease development are discussed in the context of the potential for genetically engineering disease‐resistant plants.     

Multiple protein sequence alignment from tertiary structure comparison: assignment of global and residue confidence levels.

An algorithm is presented for the accurate and rapid generation of multiple protein sequence alignments from tertiary structure comparisons. A preliminary multiple sequence alignment is performed using sequence information, which then determines an initial superposition of the structures. A structure comparison algorithm is applied to all pairs of proteins in the superimposed set and a similarity tree calculated. Multiple sequence alignments are then generated by following the tree from the branches to the root. At each branchpoint of the tree, a structure-based sequence alignment and coordinate transformations are output, with the multiple alignment of all structures output at the root. The algorithm encoded in STAMP (STructural Alignment of Multiple Proteins) is shown to give alignments in good agreement with published structural accounts within the dehydrogenase fold domains, globins, and serine proteinases. In order to reduce the need for visual verification, two similarity indices are introduced to determine the quality of each generated structural alignment. Sc quantifies the global structural similarity between pairs or groups of proteins, whereas Pij' provides a normalized measure of the confidence in the alignment of each residue. STAMP alignments have the quality of each alignment characterized by Sc and Pij' values and thus provide a reproducible resource for studies of residue conservation within structural motifs.