Chloromycetin in the nutrition of the silkworm Bombyx mori L.—II. Influence on digestion and utilization of protein,fat, and minerals

The nature and extent of the influence of chloromycetin on larval digestion and utilization of the principal dietary constituents—the proteins, fats, and minerals—was studied. The antibiotic was shown to influence favourably the utilization of all the constituents studied. The results have been discussed in the light of these and other findings.     

Genetic diversity and population genetic structure of three endemic species of Mammillaria (Cactaceae) from the Tehuacán Valley in central México

Biodiversity and Conservation - Mammillaria hernandezii, M. dixanthocentron and M. lanata are endemic and threatened cactus species that inhabit the Tehuacán Valley, an arid zone in southern...     

Chloromycetin in the nutrition of the silkworm Bombyx mori L.—III: Influence on gut weight,oxygen uptake,and glucose absorption

Administration of chloromycetin has been found to enhance the oxygen uptake of the gut of the silkworm. The possibility that this increase might have been due to a thinning of the gut wall has been ruled out since the reduction in gut weight set in much later. Although glucose ultilization by the gut has been found to be increased in vitro, increase in oxygen uptake has not been affected in the presence of glucose. The possibility of a hormonal stimulation has been discussed.     

Fine structure of the eggshells of four primitive moths: Hepialus hecta (L.),Wiseana umbraculata (Guénée) (Hepialidae), Mnesarchaea fusilella walker and M. Acuta philp. (Mnesarchaeidae) (Lepidoptera,Exoporia)

The eggshells of Hepialus hecta, Wiseana umbraculata (Hepialidae) and of Mnesarchaea fusilella (Mnesarchaeidae) (Lepidoptera, Exoporia) were studied by scanning electron microscopy (SEM) and transmission (TEM) electron microscopy. All 3 species show a very similar surface sculpture of the micropylar region which, however, is very different from the eggs of the Ditrysia. The micropylar plate is large and oval. There are only 2 or 3 micropylar openings. In the hepialid moths, the surface of the egg's main body is characterized by spherical protuberances. The radial fine structure of the eggshells of all 3 species as well as of alcohol-stored eggs of Mnesarchaea acuta (Mnesarchaeidae) is basically identical to the eggshell of Korscheltellus lupulinus (Hepialidae). The chorion consists of only one layer, which, in the hepialid species, shows a crystalline-like fine structure. The vitelline envelope is composed of a thin, laminated, outer layer (V-2) and a thick, rigid, inner layer (V-1) that is traversed by large numbers of canals. This kind of eggshell architecture is distinctively different from that of the ditrysian Lepidoptera.     

Comparative analysis of the sequences of the three collagen chains α1(I), α2 and α1(III): Functional and genetic aspects

The amino acid sequences of type I collagen containing α1(I) and α2 chains at a ratio of 2:1, and of type III collagen consisting of α1 (III) chains are known. A statistical analysis of the sequences of these α chains is presented. The inter-chain comparison showed a high level of homology between the three α chains. The interactive amino acids, such as the polar charged and part of the hydrophobic residues responsible for the assembly of the molecules, are strongly conserved. The intra-chain analysis revealed that the α chains are divided into four related D units, each with a length of 234 residues. Between the D units within a chain the polar residues show a higher variability than the hydrophobic amino acids.Besides the D units, other periodicities such as $\text{D}\text{3}$ (78 residues), $\text{D}\text{6}$ (39 residues), $\text{solD}\text{11}$ (21 residues) and $\text{solD}\text{13}$ (18 residues) were observed, particularly in α1 (I) and α1 (III). The D unit is a functional repeat that is formed by the interactive polar charged and hydrophobic residues and which determines the aggregation of the molecules. The $\text{solD}\text{3}$ unit is mainly pronounced by the non-interactive residues such as proline and alanine and appears to be a reminiscence of a primordial gene. The smaller periodic repeating units may be considered as additional genetic units or as structural units, which determine the triplehelical pitch and thus the lateral aggregation of the molecules.In contrast to α1 (I) and α1 (III), the α2 chain shows less regularity in its internal structure.     

Subunit structure and higher order assembly of the hemocyanins of the Melongenidae family: Melongena corona (Gmelin), Busycon canaliculatum (Linné), B. carica (Gmelin), B. contrarium (Conrad), and B. spiratum (Lamarck)

1. The hemocyanins of the Melongenidae family of marine gastropods: Melongena corona, Busycon canaliculatum, B. carica, B. contrarium, and B. spiratum exist in solution as multi-decameric aggregates characterized by sedimentation coefficients of approximately 105 S, 130 S, 150 S, 170 S, and higher values, corresponding to di-, tri-, tetra-, penta-, and larger multi-decameric particles. 2. The hemocyanins of B. contrarium and B. carica seem to form the largest decameric aggregates with the tri- to penta-decamers respresenting the major constitutents. Scanning transmission electron microscopy (STEM), both of unstained, freeze-dried and negatively-stained specimens, shows the presence of discrete aggregates consisting of up to ten decameric units. 3. The particle masses as determined by STEM mass measurements for individual molecules gave integral multiples of from 4.2 x 10(6) to 4.4 x 10(6) daltons ranging from about 8.2 x 10(6) daltons for the typical di-decamer of B. canaliculatum hemocyanin to as high as about 39 x 10(6) and 43 x 10(6) for the nano-and deca-decamers of B. contrarium hemocyanin. 4. The appearance of the higher multi-decamers in both negatively-stained and freeze-dried specimens suggest that they are formed by the addition of decameric units to a single di-decameric unit "tail-wise" in both directions. The higher aggregates formed seem to terminate with a closed head or collar at both ends of the assembly.     

Population genetic structure of two primary parasitoids of Spodoptera frugiperda (Lepidoptera), Chelonus insularis and Campoletis sonorensis (Hymenoptera): to what extent is the host plant important?

Plant chemistry can strongly influence interactions between herbivores and their natural enemies, either by providing volatile compounds that serve as foraging cues for parasitoids or predators, or by affecting the quality of herbivores as hosts or prey. Through these effects plants may influence parasitoid population genetic structure. We tested for a possible specialization on specific crop plants in Chelonus insularis and Campoletis sonorensis, two primary parasitoids of the fall armyworm, Spodoptera frugiperda. Throughout Mexico, S. frugiperda larvae were collected from their main host plants, maize and sorghum and parasitoids that emerged from the larvae were used for subsequent comparison by molecular analysis. Genetic variation at eight and 11 microsatellites were respectively assayed for C. insularis and C. sonorensis to examine isolation by distance, host plant and regional effects. Kinship analyses were also performed to assess female migration among host‐plants. The analyses showed considerable within population variation and revealed a significant regional effect. No effect of host plant on population structure of either of the two parasitoid species was found. Isolation by distance was observed at the individual level, but not at the population level. Kinship analyses revealed significantly more genetically related—or kin—individuals on the same plant species than on different plant species, suggesting that locally, mothers preferentially stay on the same plant species. Although the standard population genetics parameters showed no effect of plant species on population structure, the kinship analyses revealed that mothers exhibit plant species fidelity, which may speed up divergence if adaptation were to occur.     

Conservation by trans-border cooperation: population genetic structure and diversity of geoffroy’s bat (Myotis emarginatus) at its north-western european range edge

Biodiversity and Conservation - In the European Union, all bat species are strictly protected and member states must ensure their conservation. However, if populations are genetically structured,...     

Identity and genetic structure of eggplant fruit and shoot borer,Leucinodes orbonalis Guenée (Lepidoptera:Crambidae) populations in the Philippines inferred from morphological traits and COI sequence data

Morphological and molecular analysis of 15 Philippine populations of eggplant fruit and shoot borer (EFSB), Leucinodes orbonalis Guenée were conducted to determine if these populations are constituted singly by L. orbonalis or by different species and to assess the level of variability among them. Morphometric analysis of five genital traits of 850 male adult EFSB from field populations and analysis of the COI gene sequence of 879 F₁ EFSB larvae from 15 main eggplant-producing provinces identified all individuals as belonging to L. orbonalis. Principal Component Analysis of five morphometric genital characters revealed high similarity among the EFSB populations regardless of geographic location. Thirteen (13) sequence variants (haplotypes) were identified, with one haplotype predominant and widespread throughout the country. The remaining haplotypes occurred rarely and differed from the widespread haplotype by one mutation. Overall, the EFSB populations from Philippines exhibited low nucleotide and haplotype diversity, indicating low genetic diversity. Topologies from a maximum likelihood tree indicate all thirteen haplotypes cluster in a single clade with EFSB populations from India and other South-East Asian countries. Further analysis with the Generalized Mixed Yule Coalescent (GMYC) method classified the different haplotypes into a single GMYC entity. Combined with morphometric analysis, differences between haplotypes are not suggestive of any subspecies. Negative values of Tajima's D and Fu's F_s tests combined with the phylogenetic analysis and overall low genetic diversity of Philippine populations support the hypothesis that EFSB is not endemic but introduced to the Philippines.     

Can larvae of the pod-borer,Helicoverpa armigera (Lepidoptera: Noctuidae), select between wild and cultivated pigeonpea Cajanus sp. (Fabaceae)?

Experiments were conducted to observe the feeding and food selection-behaviour of different instars of the pod-borer Helicoverpa armigera (Hübner) in response to choices between the cultivated and a wild species of Cajanus. First and second instars fed upon a cultivated variety of Cajanus cajan in preference to a wild species, C. scarabaeoides and on flowers of C. cajan, rather than pods or leaves of C. cajan. First and second instars preferred pods of C. scarabaeoides with trichomes removed to pods with trichomes present. All instars fed upon pods of C. cajan rather than those of C. scarabaeoides. Solvent extraction of the pod surfaces affected the feeding of larvae, in some instances. They preferred the unextracted pods of C. cajan; the extracted pod of C. scarabaeoides (first and second instars) or the unextracted pod of C. scarabaeoides (fourth and fifth instars). Glass-fibre disc bioassays showed that the methanol, hexane and water extracts from the pod-surface of C. cajan stimulated the feeding of fifth instars. The experiments have shown that characteristics of C. cajan, such as either the compounds present or the type and distribution of trichomes on the plant surfaces, can determine the susceptibility of C. cajan to pod-borer larvae.     

Genome sizes of Eucomis L’Hér. (Hyacinthaceae) and a description of the new species Eucomis grimshawii G.D.Duncan & Zonneveld

Nuclear genome size, as measured by flow cytometry with propidium iodide, was used to investigate the relationships within the genus Eucomis L’Hér. (Hyacinthaceae). Most species of Eucomis have the same basic chromosome number, x = 15. However, the somatic DNA 2C-value (2C) is shown to range from 21 to 31 pg for the diploids. The largest genome contains roughly 10¹⁰ more base pairs than the smallest. Genome sizes are evaluated here in combination with available morphological and geographical data. Therefore, the taxonomy proposed here is not based on genome size alone. The genus Eucomis, as here determined, has 12 species. These can be divided into two groups: mainly dwarf diploid species and large-sized, tetraploid species. A small diploid plant, Eucomis (autumnalis subsp.) amaryllidifolia, is restored to species status, as a diploid subspecies seems incongruent with an allotetraploid Eucomis autumnalis. Moreover, as a diploid it is separated reproductively from the allotetraploid E. autumnalis. A new diploid species that has the lowest C value, E. grimshawii, is described here. On the basis of DNA content and other morphological characters, possible parents are suggested for all tetraploid species. Nuclear DNA content as measured by using flow cytometry may conveniently be used to produce systematic data. It is applicable even in dormant bulbs or sterile plants for the monitoring of the trade in bulbous species.     

Does genetic population structure of Ambrosina bassii L. (Araceae,Ambrosineae) attest a post-Messinian land-bridge between Sicily and Africa?

Aim of the present work is the analysis (through the study of enzyme polymorphism) of Sicilian and African (Tunisian) populations of Ambrosina bassii, a small perennial endemic to the Central-Western Mediterranean basin, in order to verify if the complex geological history of this part of the Mediterranean area left its mark in the present-day genetic structure of this taxon. Starch gel allozyme electrophoresis of seven putative loci of A. bassii was employed to estimate genetic diversity, genetic structure and gene flow. Populations from Sicily, Tunisia and Sardinia (as outgroup) were sampled. Results show that Sicily populations have 4 private alleles, Sardinia 3, Tunisia just one. One allele is private to both Sardinia and Tunisia, another one to Sardinia and Sicily. Even if there are no alleles private to Sicily and Tunisia, “cluster analysis” (based on Nei's genetic distances), “non-metric multidimensional scaling” (computed on the basis of a matrix with F_ST values between populations) and Bayesian analysis point out a clear isolation of Sardinian populations, and a greater similarity between Sicilian and Tunisian populations compared to Sardinian ones. The strong genetic affinity between populations from Sicily and Tunisia, considering the very low dispersal ability of the species, gives evidence of a recent continuity between the populations as well as between the two areas. Considering also the estimates of divergence times, a post-Messinian terrestrial connection between the two landmasses can be hypothesized.     

Culture-independent analysis of an endophytic core microbiome in two species of wheat: Triticum aestivum L. (cv. ‘Hondia’) and the first report of microbiota in Triticum spelta L. (cv. ‘Rokosz’)

The main goal of the study was to determine the structure of endophytic bacteria inhabiting different parts (endosperm, germ, roots, coleoptiles, and leaves) of two wheat species, Triticum aestivum L. (cv. ‘Hondia’) and Triticum spelta L. (cv. ‘Rokosz’), in order to provide new knowledge about the stability and/or changeability of the core microbiome in different plant organs. The endophytic core microbiome is associated with plants throughout their whole life cycle; however, plant organs can determine the actual endophytic community. Therefore, next generation sequencing with MiSeq Illumina technology was applied to identify the endophytic microbiome of T. aestivum and T. spelta. Bioinformatic analyses were performed with the use of the DADA2(1.8) package and R software (3.5.1).It was demonstrated that wheat, which is an important crop plant, was associated with beneficial endophytic bacteria inside the endosperms, germs, roots, leaves, and coleoptiles. Importantly, for the first time, biodiversity was recognized in the coleoptiles of the investigated wheat species. Flavobacterium, Pseudomonas and Janthinobacterium were shown to be common genera for both tested wheat cultivars. Among them, Pseudomonas was found to be the only endophytic genus accompanying both wheat species from the endosperm stage to the development of the leaf. Paenibacillus was recognized as a core genus for the ‘Hondia’ cv., whereas Pedobacter and Duganella constituted the core microbiome in the ‘Rokosz’ cv. In addition, the first insight into the unique and yet unrecognized endophytic microbiome of T. spelta is presented.     

Geographical variation in the genetic diversity and composition of the endangered queen conch Strombus gigas (Mesogastropoda: Strombidae) from Yucatán, México

In Mexico and elsewhere in the Caribbean, the queen conch Strombus gigas is an endangered species. Understanding the genetic connectivity of their populations will support management strategies for long-term conservation of the species. Genetic diversity and population differentiation was assessed from samples collected at Banco Chinchorro and Isla Cozumel in the Mexican Caribbean and at Arrecife Alacranes in the Gulf of Mexico. Samples were obtained from the commercial capture at Banco Chinchorro (n = 50) and Isla Cozumel (n = 40) on March 2004. On November 2004, a non-invasive method for the Arrecife Alacranes sampling was applied, taking the hemolymph of live animals (n = 65) and releasing them to the wild. The mitochondrial DNA variation at two genes (COI and Cyt-b) was analyzed. Genetic diversity at the three locations ranged between 0.55-0.65 in COI and 0.87-0.94 in Cyt-b, showing no bottleneck evidences. A non-significant fixation index (F(ST) = 0.019, p = 0.161) and a Maximum Parsimony Network tree that did not show particular clades associated with any of the geographical locations, suggested a lack of statistically significant genetic differentiation among populations. Nevertheless, the cline patterns observed in both genetic diversity and haplotypic frequencies from Banco Chinchorro through Arrecife Alacranes, and the larger genetic distance between these locations from those between Isla Cozumel, Banco Chinchorro and Arrecife Alacranes, suggest the possibility of a pattern of isolation-by distance. The role of the main current systems over the potential genetic differences in S. gigas populations along the Mexican Caribbean, and the conservation management of S. gigas at these locations as discrete units is discussed.