Geographic control of Titan's mid-latitude clouds

Observations of Titan's mid-latitude clouds from the W. M. Keck and Gemini Observatories show that they cluster near 350 degrees W longitude, 40 degrees S latitude. These clouds cannot be explained by a seasonal shift in global circulation and thus presumably reflect a mechanism on Titan such as geysering or cryovolcanism in this region. The rate of volatile release necessary to trigger cloud formation could easily supply enough methane to balance the loss to photolysis in the upper atmosphere.     

The Relevance of Species Concepts in Sustainable Forestry

Species concepts and the definition of a species are discussed in the context of sustainable forest management and the sustainability of biological systems in general. Sustainable forestry requires that the habitats created by silvicultural manipulation match the ecological niches of the species being managed, enabling them not only to grow but to reproduce themselves so they can persist on the landscape beyond the current rotation. For this to be possible, foresters must be able to identify species and understand how species are defined.     

The activity of some pyrethroids against Periplaneta americana and Blattella germanica

The knockdown and contact killing actions of various pyrethroids were compared using Blattella germanica and Periplaneta americana. A wide range of knockdown activity was found; 5-benzyl-3-furylmethyl (1R)-cis-3-(dihydro-2-oxo-3-thienylidenemethyl)-2,2-dimethylcyclopropanecarboxylate (RU 15525) acted fastest, more rapidly than pyrethrins, against B. germanica as well as having a low LD₅₀ value. Topical application and direct spray tests showed that (S)-α-cyano-3-phenoxybenzyl (1R)-cir-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate (NRDC 161) was more active as a killing agent, by an order of magnitude, than cismethrin, the next most active compound, and also had considerable knockdown activity. Piperonyl butoxide generally had little synergist effect. Female P. americana were over three times more tolerant than males to a range of insecticides applied topically. Residual knockdown action in the WHO resistance test was observed to provide baseline data. There was little overlap in speed of action between pyrethroids and other insecticides among the compounds tested.     

Intake of trichostrongylid larvae by goats and sheep grazing together

SUMMARY Cashmere goats and Merino sheep were grazed together at 7.5 animals per ha on annual rye grass and clover pasture in southern Victoria, a winter rainfall area. Intake of parasitic larvae was measured in oesophageal extrusa samples collected from 2 animals of each species, 4 times in one week, on 7 occasions between mid-March (autumn) and mid-June (winter). Pasture contamination with larvae was measured at the same times. The number of larvae per kg of green grass was lower than on green clover; the most heavily contaminated portion of the pasture was the mat of dead herbage on the ground. The diet selected by goats contained more green grass and dead herbage and less clover that that of sheep (P < 0.01). Goats ingested 643 infective trichostrongylid larvae per kg dry matter intake (DMI) versus 274 per kg DMI for sheep in autumn, increasing to 1892 versus 1143 in early winter. The heavier trichostrongylid burdens of goats compared with sheep, when grazed together, are due in part to greater rates of infection consequent on different grazing patterns as well as greater susceptibility to infection.     

Expression of Genes in the Canine Pre‐implantation Uterus and Embryo: Implications for an Active Role of the Embryo Before and During Invasion

The aim of the present study was to assess genes expressed in maternal uterine tissue and pre‐implantation embryos which are presumably involved in maternal recognition and establishment of canine pregnancy. For this purpose, 10 pregnant bitches were ovariohysterectomized between days 10 and 12 after mating. Four non‐pregnant bitches served as controls. Early pregnancy was verified by flushing the uterine horns with PBS solution. The collected embryos (n = 60) were stored deep‐frozen (?80°C). Uterine tissue was excised, snaps frozen in liquid nitrogen and homogenized using TRI Reagent. All embryos from one litter were thawed together and also homogenized in TRI Reagent. RT‐PCR was performed to prove mRNA expression of progesterone receptor, key enzymes of the prostaglandin synthesis pathway, selected growth factors, cytokines, immune cell receptors, major histocompatibility complex (MHC) and matrix‐metalloproteinases (MMP). Only pregnant uteri revealed the presence of mRNA for interferon (IFN)‐γ, IL‐4 and CD‐8, which resembles the milieu in humans and other mammalians. Similarly, in day 10 embryos, mRNA for transforming growth factor‐β, insulin‐like growth factor‐1,‐2, hepatocyte growth factor, leukaemia inhibitor factor, tumour necrosis factor‐α, interleukin‐1β,‐6,‐8, cyclooxygenase‐2, CD4⁺ cells, and MMP‐2 and ‐9 were detected, but not MHC‐I or ‐II. We therefore suppose that the canine embryo, like its human counterpart, actively initiates measures to prevent attacks from the maternal immune system to prepare its own adhesion, nidation, growth and further development.     

Lactoferrin increases sperm membrane functionality of frozen equine semen

During cryopreservation, sperm was submitted to an increase in reactive oxygen species generation. This work aimed to improve the quality of frozen equine sperm after the addition of antioxidants lactoferrin (Lf) and catalase (Cat) to a freezing extender. Semen from six stallions was frozen with the extenders: F1) control, INRA 82 freezing extender, F2) F1 + 500 μg/ml Lf and F3) F1 + 200 IU/ml Cat. After thawing, sperm motility parameters, membrane functionality and integrity, and acrosome integrity and spontaneous acrosome‐reacted sperm were evaluated with a computer‐assisted sperm analysis, a hypoosmotic swelling test and epifluorescent microscopy, respectively. Nitrite, hydroperoxide and iron concentrations of frozen semen were measured with spectrophotometry. The percentage of functional membrane sperm treated with Lf was higher (50.7% ± 11.6%) compared to that of the control (37.6% ± 15.6%), while the iron (61.4 ± 11.6 vs 73.3 ± 13.8 mg/dl) and nitrite concentrations (16.3 ± 7.1 vs 25.9 ± 4.2 μM/μg protein) were lower, respectively (p < .05). Thus, it can be suggested that Lf protect stallion spermatozoon during freezing as it has increased the percentage of sperm with functional membrane and decreased the lipid oxidant agents.     

Lack of a relationship between concentrations of plasma Luteinising hormone,Thyroxine and Prolactin at nine weeks of age and subsequent egg production in the domestic hen

1. The concentrations of plasma luteinising hormone (LH), thyroxine and prolactin were measured in about 200 birds from each of two homogenous strains of White Leghorn hens at 9 weeks of age and related to subsequent egg production.

2. Within each strain, no relationships were found in individual birds between the concentrations of the plasma hormones and subsequent egg production after 90, 180 and 270 d of laying.

3. Single measurements of plasma LH, thyroxine or prolactin before the onset of lay do not appear to be useful criteria for the selection of egg‐laying strains.