Stem Volume Equations for Valuable Timber Species in Mozambique

Development of stem volume for umbrella-shaped crown trees remains a big challenge for efficient use of forest resources in Mozambique. In this study, species-specific stem volume equations were developed for the first time for three of the most important timber species in Mozambique: Afzelia quanzensis Welw. (Chanfuta), Millettia stuhlmannii Taub. (Jambire), and Pterocarpus angolensis D.C. (Umbila). The study was carried out at three locations in Mozambique: Inhaminga, Mavume, and Tome covering 58 trees from which, 24 of Chanfuta, 15 of Jambire, and 19 of Umbila. The volume of the sampled stem sections (logs) was calculated using Smalian’s formula, where stem volume total was obtained through the sum of the respective defined sections. Using a nonlinear procedure, different volume models were tested for each tree species independently. The coefficient of the determination of the tested equations in the tree species ranged from .90 to .95, making the equations potential candidate models for the stem volume equations object of the study. Based on statistical parameters analysis, the best fit nonliner power equation was Equation 2 with the lowest AICc and lowest average absolute bias. The stem volume for the studied species is better explained by models including both diameter and height as explanatory variables.     

Breeding for low seed caffeine content of coffee (Coffea L.) by interspecific hybridization

Summary Seeds from open-pollinated flowers collected from hybrids of several Coffea species were analysed for caffeine content. The caffeine content was not always intermediary to that of the parents; higher and lower values were found. Diploid F₁ hybrids between accessions of C. eugenioides and C. salvatrix showed the lowest seed caffeine content. Seeds of the tetraploid hybrids C. arabica × C. salvatrix or C. arabica × C. eugenioides hybrids presented low caffeine content. The possibility of breeding coffee to reduce the caffeine content in the seeds by interspecific hybridization of C. arabica with other Coffea species is discussed.     

A new type of pterocarpanquinone that affects Toxoplasma gondii tachyzoites in vitro

Toxoplasma gondii, the agent of Toxoplasmosis, is an obligate intracellular protozoan able to infect a wide range of vertebrate cells, including nonprofessional and professional phagocytes. Therefore, drugs must have intracellular activities in order to control this parasite. The most common therapy for Toxoplasmosis is the combination of sulfadiazine and pyrimethamine. This treatment is associated with adverse reactions, thus, the development of new drugs is necessary. In previous studies, naphthoquinone derivatives showed anti-cancer activity functioning as agents capable of acting on groups of DNA, preventing cancer cells duplication. These derivatives also display anti-parasitic activity against Plasmodium falciparum and Leishmania amazonensis. The derivative pterocarpanquinone tested in this work resulted from the molecular hybridization between pterocarpans and naphtoquinone that presents anti-tumoral and anti-parasitic activities of lapachol. The aim of this work was to determine if this derivative is able to change T. gondii growth within LLC-MK2 cells. The drug did not arrest host cell growth, but was able to decrease the infection index of T. gondii with an IC(50) of 2.5 μM. Scanning and transmission electron microscopy analysis showed morphological changes of parasites including membrane damage. The parasite that survived tended to encyst as seen by Dolichos biflorus lectin staining and Bag-1 expression. These results suggest that pterocarpanquinones are drugs potentially important for the killing and encystment of T. gondii.     

Phoretic dispersal of the entomopathogenic nematode Heterorhabditis amazonensis by the beetle Calosoma granulatum

Entomopathogenic nematodes (EPN) have limited ability to travel and need to adopt alternative strategies to reach hosts that are far away. They can attach themselves to an organism that acts only as a dispersal agent to transport the EPN to places that they cannot reach by themselves. The larval and adult stages of Calosoma granulatum (Coleoptera: Carabidae) beetle are important predators of caterpillars that live in the soil of Brazilian agricultural systems. The nematode Heterorhabditis amazonensis (Rhabditida: Heterorhabditidae) is a native of Brazil and plays a major role in the control of Spodoptera frugiperda (Lepidoptera: Noctuidae) caterpillars. This study assessed the ability of C. granulatum to carry and disperse H. amazonensis. The experimental arenas consisted of two types of containers with substrate connected by a plastic tube through which the insects could move freely. Only one of the containers received infective juveniles (IJ) and the other was used as the test container. We first used C. granulatum larvae and adults to evaluate the influence of different concentrations of IJs on phoretic behavior. Then different distances traveled by the adult beetle were tested to measure their effect on IJ transport. The results showed that C. granulatum is a good phoretic dispersal agent and the transport of IJs by the larvae is less influenced than transport by the adult, by a change in the IJ concentration. The distance traveled by the adult influences the number of EPN carried and the detection of phoresy even at greater distances (40 cm) indicates that C. granulatum is capable of transporting the EPN for distances greater than those evaluated.     

Genetic dissection of the relationship between plant architecture and yield component traits in soybean (Glycine max) by association analysis across multiple environments

Plant architecture and yield components are critical for the determination of seed yield in soybean. In this study, we performed genetic association analysis to dissect the relationships between plant architecture and yield component traits. Two hundred and nineteen accessions were employed, and eight agronomic traits were evaluated in six environments. Our results revealed strong positive correlations of plant architecture traits with yield components and the significant association of 4 SNPs with plant architecture traits and of 7 SNPs with yield component traits in two or more environments. Eight SNPs were co‐associated with two traits. Based on the phenotypic effects of the alleles of the detected SNPs, the best alleles were mined for twenty‐three distinct SNPs. Fifteen typical carrier materials harbouring the best allele effects were also mined. Twenty parental combinations were proposed by pyramiding possible alleles per SNP in one individual (excluding possible epistatic effects). These proposed combinations with the best alleles and carrier materials will aid in the improvement of targeted traits and marker‐assisted selection (MAS) efficiency in soybean breeding.     

Inbreeding depression on production and reproduction traits of buffaloes from Brazil

The objective of this study was to evaluate the influence of inbreeding depression on traits of buffaloes from Brazil. Specifically, the traits studied were body weight at 205 and 365 days of age, average daily gain from birth to 205 days (ADG_205), average daily gain between 205 and 365 days (ADG205_365) in Mediterranean buffaloes, and milk yield, lactation length, age of first calving and calving intervals in Murrah buffaloes. Inbreeding effects on the traits were determined by fitting four regression models (linear, quadratic, exponential and Michaelis‐Menten) about the errors generated by the animal model. The linear model was only significant (P < 0.05) for growth traits (exception of ADG205_365). The exponential and Michaelis‐Menten models were significant (P < 0.01) for all the studied traits while the quadratic model was not significant (P > 0.05) for any of the traits. Weight at 205 and 365 days of age decreased 0.25 kg and 0.39 kg per 1% of increase in inbreeding, respectively. The inbred animals (F = 0.25) produced less milk than non‐inbred individuals: 50.4 kg of milk. Moreover, calving interval increased 0.164 days per 1% of increase in inbreeding. Interestingly, inbreeding had a positive effect on age at first calving and lactation length, decreasing age of first calving and increasing lactation length.     

Population structure and genetic variability in the Murrah dairy breed of water buffalo in Brazil accessed via pedigree analysis

The objective of this study was to use pedigree analysis to evaluate the population structure and genetic variability in the Murrah dairy breed of water buffalo (Bubalus bubalis) in Brazil. Pedigree analysis was performed on 5,061 animals born between 1972 and 2002. The effective number of founders (fe) was 60, representing 6.32?% of the potential number of founders. The effective number of ancestors (fa) was 36 and the genetic contribution of the 17 most influent ancestors explained 50?% of the genetic variability in the population. The ratio fe/fa (effective number of founders/effective number of ancestors), which expresses the effect of population bottlenecks, was 1.66. Completeness level for the whole pedigree was 76.8, 49.2, 27.7, and 12.8?% for, respectively, the first, second, third, and fourth known parental generations. The average inbreeding values for the whole analyzed pedigree and for inbreed animals were, respectively, 1.28 and 7.64?%. The average relatedness coefficient between individuals of the population was estimated to be 2.05?%??the highest individual coefficient was 10.31?%. The actual inbreeding and average relatedness coefficient are probably higher than estimated due to low levels of pedigree completeness. Moreover, the inbreeding coefficient increased with the addition of each generation to the pedigree, indicating that incomplete pedigrees tend to underestimate the level of inbreeding. Introduction of new sires with the lowest possible average relatedness coefficient and the use of appropriate mating strategies are recommended to keep inbreeding at acceptable levels and increase the genetic variability in this economically important species, which has relatively low numbers compared to other commercial cattle breeds. The inclusion of additional parameters, such as effective number of founders, effective number of ancestors, and fe/fa ratio, provides better resolution as compared to the inclusion of inbreeding coefficient and may help breeders and farmers adopt better precautionary measures against inbreeding depression and other deleterious genetic effects.     

A survey on the occurrence of resistance to anthelmintics of gastrointestinal nematodes of goats in Mozambique

A survey to study the extent of anthelmintic resistance was conducted in Maputo and Gaza, two of the ten provinces of Mozambique, during February and March, 1999. A total of 12 flocks, six in Maputo and six in Gaza, was surveyed. The faecal egg count reduction test was used to assess the efficacy of three anthelmintics most often used in Mozambique, namely albendazole, fenbendazole and levamisole. The degree of resistance was calculated using two different methods, and varied according to the method used. Using the formula of Coles, Bauer, Borgsteede, Geerts, Klei, Taylor & Waller (1992), resistance to the benzimidazoles was detected in one flock in Maputo and one in Gaza, and to levamisole in three flocks in Maputo and one in Gaza. When the formula of Dash, Hall & Barger (1988) was used, however, resistance to the benzimidazoles was detected in only one flock in Maputo, and no resistance to levamisole was detected. The 12 farms surveyed were too few for conclusions to be made on the prevalence of anthelmintic resistance in goats in Mozambique as a whole. Therefore, an extensive survey at national level is needed. This study gives evidence, however, that anthelmintic resistance in nematode parasites of goats is an emerging problem, to which special attention should be paid.     

Ixodid ticks on dogs belonging to people in rural communities and villages in Maputo Province, Mozambique

The species composition and geographic distribution of ixodid ticks infesting domestic dogs owned by people in rural communities and villages in Maputo Province was established by collecting ticks from dogs at each of 27 localities spread throughout the province. Ticks were collected from a total of 132 dogs, and nine species belonging to four genera were identified. One dog was infested with six species, three with five and 13 with four species. Haemaphysalis elliptica followed by Rhipicephalus simus were present on dogs at most localities, and their geographic distribution in Maputo Province has been mapped for the first time.