Comparative chromosome mapping of 5S rDNA and 5SHindIII repetitive sequences in Erythrinidae fishes (Characiformes) with emphasis on the Hoplias malabaricus 'species complex'

Chromosomal localization of 5S rDNA and 5SHindIII repetitive sequences was carried out in several representatives of the Erythrinidae family, namely in karyomorphs A, D, and F of Hoplias malabaricus, and in H. lacerdae, Hoplerythrinusunitaeniatus and Erythrinus erythrinus. The 5S rDNA mapped interstitially in two chromosome pairs in karyomorph A and in one chromosome pair in karyomorphs D and F and in H. lacerdae. The 5SHindIII repetitive DNA mapped to the centromeric region of several chromosomes (18 to 22 chromosomes) with variations related to the different karyomorphs of H. malabaricus. On the other hand, no signal was detected in the chromosomes of H. lacerdae, H. unitaeniatus and E. erythrinus, suggesting that the 5SHindIII-DNA sequences have originated or were lost after the divergence of H. malabaricus from the other erythrinid species. The chromosome distribution of 5S rDNA and 5SHindIII-DNA sequences contributes to a better understanding of the mechanisms of karyotype differentiation among the Erythrinidae members.     

Gender and ecological restoration: time to connect the dots

Although the human dimension of ecological restoration has increasingly been recognized in recent years, the gender dimension thereof remains largely unexplored. This article aims to fill this gap in the literature by providing an overview of the current knowledge on gender and ecological restoration. Our analysis of selected academic literature on ecological restoration revealed that scholars have only marginally addressed gender issues in their publications. However, in restoration practice, various initiatives that highlight the importance of including a women's rights and gender perspective can be found. These initiatives seem to indicate that applying a gender approach to restoration practice creates a double benefit. First, integrating gender considerations into restoration efforts is desirable from a human rights and gender equality perspective. Second, different case studies suggest that integrating gender considerations can promote the efficiency and effectiveness of restoration work. Integrating a social and gender dimension into restoration policy and practice should therefore be recommended. This integration process can learn from a wide range of literature on gender and the environment, and from existing practices of gender mainstreaming in this field. Furthermore, international law provides useful policy intentions on gender and restoration that could be used as entry points. To conclude, this article summarizes the main challenges for “connecting the dots” between gender and ecological restoration and formulates some recommendations for the Society for Ecological Restoration.     

Chromosomal distribution of repetitive DNA sequences highlights the independent differentiation of multiple sex chromosomes in two closely related fish species

The arrangement of 6 repetitive DNA sequences in the mitotic and meiotic sex chromosomes of 2 Erythrinidae fish, namely Hoplias malabaricus and Erythrinus erythrinus, both with a multiple X(1)X(1)X(2)X(2)/X(1)X(2)Y sex chromosome system, was analyzed using fluorescence in situ hybridization. The distribution patterns of the repetitive sequences were distinct for each species. While some DNA repeats were species-specific, others were present in the sex chromosomes of both species at different locations. These data, together with the different morphological types of sex chromosomes and the distinct chromosomal rearrangements associated with the formation of the neo-Y chromosomes, support the plasticity of sex chromosome differentiation in the Erythrinidae family. Our present data highlight that the sex chromosomes in fish species may follow diverse differentiation patterns, even in the same type of sex chromosome system present in cofamiliar species.     

Hormone homeostasis and induction of the small-fruit phenotype in ‘Hass’ avocado

Plant hormones play an important regulatory role in growth and development of fleshy fruits and often these are synthesized in a sequence that is tissue- and/or fruit-specific. Previous studies using Hass avocado and its small-fruit phenotype as a model demonstrated a relationship between the cytokinin/abscisic acid ration and final fruit size. More detailed studies revealed that differential activity of molybdenum-cofactor-containing enzymes was in part responsible for the observed increase in abscisic acid in small Hass fruit and that the same suite of enzymes likely impacted levels of indole-3-acetic acid. The present study confirms that the inability of the seed to produce/accumulate indole-3-acetic acid is a major contributing factor and characteristic of fruit that display a small-fruit phenotype, that reduced indole-3-acetic acid levels occur concomitant with increased abscisic acid, and that cytokinin metabolism appears unchanged irrespective of fruit size. Results are discussed in relation to the role of molybdenum-cofactor-requiring enzymes in indole-3-acetic acid and abscisic acid metabolism.     

Karyotypic diversity and evolution of Loricariidae (Pisces, Siluriformes)

We present cytogenetic analyses of four fish species, belonging to four Loricariidae subfamilies: Neoplecostomus microps (Neoplecostominae) with 2n=54 chromosomes, Harttia loricariformis (Loricariinae) with 2n=56 chromosomes, Hypostomus affinis (Hypostominae) with 2n=66 chromosomes and Upsilodus sp. (Upsilodinae), with 2n=96 chromosomes. In addition to karyotypes, data on the location of 18s rDNA sites are presented, derived from indirect (silver nitrate impregnation) and direct (FISH) methods. There is only one pair of nucleolar organizing regions (NORs) per species, except in H. affinis. Diversity and NOR macrokaryotypic evolution in the species analyzed are discussed in relation to the evolution of the Loricariidae as a whole. In addition, a revision of the cytogenetic data available for this family is presented.     

Heterochromatin characterization of four fish species of the family Loricariidae (Siluriformes)

The karyotypic structures and the composition and distribution of the heterochromatin in the karyotypes of four catfish species belonging to four Loricariidae subfamilies were analysed, namely: Neoplecostomus microps (Neoplecostominae) with 2n=54 chromosomes, Harttia loricariformis (Loricariinae) with 2n=56 chromosomes, Hypostomus affinis (Hypostominae) with 2n=66 chromosomes and Upsilodus sp. (Upsilodinae) with 2n=96 chromosomes. The amount and composition of heterochromatin was quite unequal among the studied species, being copious and mainly GC-rich in Upsilodus sp. and scarce and balanced in H. loricariformis. All of the H. affinis heterochromatin is GC-rich and related with nucleolar organizing regions. N. microps show low quantity of interstitial and GC-rich heterochromatin, one of them being related with NORs. Trends in the macrokaryotypic diversification as well as in the distribution pattern of the heterochromatin are discussed.     

Heteromorphic sex chromosome system with an exceptionally large Y chromosome in a catfish Steindachneridion sp. (Pimelodidae)

The chromosomes and banding patterns of Steindachneridion sp., a large catfish (Pimelodidae), endemic to the Igua?u River, Brazil, were analyzed using conventional (C-, G-banding) and restriction enzyme banding methods. The same diploid number (2n = 56) as in other members of the genus and the family was found but the karyotype displayed an XX/XY sex chromosome system. The X chromosome was the smallest submetacentric, while the Y was the largest chromosome in the karyotype. Meiotic analysis showed 27 autosomal bivalents plus one heteromorphic XY bivalent during spermatogenesis. Sex chromosomes had no particular pattern after C-banding but G- and restriction enzyme bandings showed specific banding characteristics. The present finding represents the first report of a well-differentiated and uncommon sex chromosome system in the catfish family Pimelodidae.     

Saccharomyces cerevisiae-based molecular tool kit for manipulation of genes from gram-negative bacteria

A tool kit of vectors was designed to manipulate and express genes from a wide range of gram-negative species by using in vivo recombination. Saccharomyces cerevisiae can use its native recombination proteins to combine several amplicons in a single transformation step with high efficiency. We show that this technology is particularly useful for vector design. Shuttle, suicide, and expression vectors useful in a diverse group of bacteria are described and utilized. This report describes the use of these vectors to mutate clpX and clpP of the opportunistic pathogen Pseudomonas aeruginosa and to explore their roles in biofilm formation and surface motility. Complementation of the rhamnolipid biosynthetic gene rhlB is also described. Expression vectors are used for controlled expression of genes in two pseudomonad species. To demonstrate the facility of building complicated constructs with this technique, the recombination of four PCR-generated amplicons in a single step at >80% efficiency into one of these vectors is shown. These tools can be used for genetic studies of pseudomonads and many other gram-negative bacteria.     

Banding pattern of A and B chromosomes of Prochilodus lineatus (Characiformes, Prochilodontidae), with comments on B chromosomes evolution

B chromosomes in Prochilodus lineatus, a migratory neotropical fish, were analyzed in a comparative study among populations from the Dourada lagoon (State of Paraná, Brazil) and from Mogi-Guaçu river (State of São Paulo, Brazil). The data on C-banding and fluorescent in situ hybridization with a satellite DNA probe (SATH1), indicate that the small metacentric B chromosome might correspond to an isochromosome. On the other hand, both populations presented a distinct set of B chromosomes, differentiated either by their number and by the presence of variant B types in the population from Mogi-Guaçu river. The present results indicate that the B chromosomes of P. lineatus should have an ancient origin, and have undergone a differential evolutionary pathway among distinct populations.