First reported case of spontaneous hermaphrodism in female date palm (Phoenix dactylifera L.), cv ‘Alligue’

The date palm (Phoenix dactylifera L.) is dioecious with male flowers deficient in functional gynoecium and female flowers deficient in functional androecium borne on separate palms. The presence of male and female flowers on the same plant, a phenomenon known as monoecy, is unusual in male date palms.

This study reports for the first time on hermaphrodite (bisexual) flowers borne by two female date palms, ‘Alligue’, that were found growing in an open field in Degache, southern Tunisia. The observations on these two female palms were compared with hermaphrodite male date palms growing in the same location. Hermaphrodite female date palm inflorescence branches bear female flowers predominantly near their base, in contrast to the hermaphrodite flowers that are found primarily toward their upper part. The position of the hermaphrodite flowers in hermaphrodite male date palms is reversed: inflorescence branches bear male flowers toward the upper part while the hermaphrodite flowers are found at the base. Histological examination of female hermaphrodite flowers revealed that they had three carpels and 1–6 stamens. Hermaphrodite flowers on male plants were usually also composed of three carpels of variable size, and six stamens. Hermaphrodite flowers on both female and male palm trees turn generally into parthenocarpic fruits. The present data support the theory that dioecious plants are derived from a common hermaphrodite ancestor. Floral hermaphroditism in date palm should be investigated in relation to the in planta self-fertilization process to identify sex markers and genes that control sex organ development.     

A Mass Balance Mercury Budget for a Mine-Dominated Lake: Clear Lake, California

The Sulphur Bank Mercury Mine (SBMM), active intermittently from 1873–1957 and now a USEPA Superfund site, was previously estimated to have contributed at least 100 metric tons (10⁵ kg) of mercury (Hg) into the Clear Lake aquatic ecosystem. We have confirmed this minimum estimate. To better quantify the contribution of the mine in relation to other sources of Hg loading into Clear Lake and provide data that might help reduce that loading, we analyzed Inputs and Outputs of Hg to Clear Lake and Storage of Hg in lakebed sediments using a mass balance approach. We evaluated Inputs from (1) wet and dry atmospheric deposition from both global/regional and local sources, (2) watershed tributaries, (3) groundwater inflows, (4) lakebed springs and (5) the mine. Outputs were quantified from (1) efflux (volatilization) of Hg from the lake surface to the atmosphere, (2) municipal and agricultural water diversions, (3) losses from out-flowing drainage of Cache Creek that feeds into the California Central Valley and (4) biotic Hg removal by humans and wildlife. Storage estimates include (1) sediment burial from historic and prehistoric periods (over the past 150–3,000 years) from sediment cores to ca. 2.5m depth dated using dichloro diphenyl dichloroethane (DDD), ²¹⁰Pb and ¹⁴C and (2) recent Hg deposition in surficial sediments. Surficial sediments collected in October 2003 (11 years after mine site remediation) indicate no reduction (but a possible increase) in sediment Hg concentrations over that time and suggest that remediation has not significantly reduced overall Hg loading to the lake. Currently, the mine is believed to contribute ca. 322–331 kg of Hg annually to Clear Lake, which represents ca. 86–99% of the total Hg loading to the lake. We estimate that natural sedimentation would cover the existing contaminated sediments within ca. 150–300 years.     

Effect of high temperature and feeding level on energy utilization in piglets

The effect of temperature (23 or 33 degrees C) and feeding level on components of energy balance was studied in seven groups of individually reared Piétrain x (Landrace x Large White) littermate piglets. Within each litter, one pig was reared at 23 degrees C and given a predefined feeding level close to ad libitum (23AL pigs), one was reared at 33 degrees C and also fed close to ad libitum (33AL), and one was reared at 23 degrees C and pair-fed to the 33AL pig (23PF). Piglets of one litter were acclimated during 2 to 4 wk to their experimental temperature in temperature-controlled rooms before being transferred (one per week) to a respiration chamber for measurement of nitrogen and energy balances. The average initial BW was 22.4 kg. The data on O2 consumption, CO2 production, and physical activity were collected over seven consecutive days and used to calculate total heat production (HPtot) and its components: fasting heat production (FHP), heat production due to physical activity (HPact), and thermic effect of feed (TEF). A preliminary trial was conducted in which heat production was measured in three piglets according to a Latin square design at 23, 25, and 27 degrees C. Total heat production was, but activity-free heat production was not, affected by temperature, and no firm conclusions could be drawn as to whether 23 degrees C was within the thermoneutral zone of fed piglets. In Trial 2, the combination of increased temperature and reduced feed intake resulted in a 20% lesser heat production in 33AL than in 23AL pigs. This was due to a reduction in both TEF (-39%) and FHP (0.642 vs 0.808 MJ x d(-1) x kg BW-0.60). Despite the shorter duration of standing activity, HPact was slightly higher at 33 degrees C, probably due to hyperventilation at this temperature. With similar feeding levels (23PF vs 33AL), HPtot and activity-free heat production were less at 33 degrees C and energy retention as protein (+6%) and fat (+31%) was increased. Because HPact was similar for both treatments, the greater energy retention for 33AL seemed to be due to a greater utilization of feed energy or to a reduced maintenance requirement (i.e., reduced FHP). However, the type of stress imposed on 23PF and 33AL pigs was different and may have affected energy metabolism. The results suggest that the reduction in heat production of piglets at high ambient temperatures is caused by a reduction in voluntary feed intake and differences in energetic efficiency. The mechanisms for the lesser efficiency at 23 degrees C compared to 33 degrees C (at the same level of feed intake) remain unclear.     

Comparison of the efficacy of macrocyclic lactone anthelmintics,either singly or in combination with other anthelmintic(s), in nine beef herds in southern NSW

Anthelmintic resistance (AR) is a well-recognized challenge in farmed ruminants. The use of anthelmintics in combination is one of the strategies recommended to slow the rate of AR development. Two studies were undertaken in 2017 and 2019 to assess the efficacy of single-dose macrocyclic lactone (ML) anthelmintic and ML combination drenches. In total, 11 Faecal Egg Count Reduction Trials (FECRTs) were set up in 10 different beef herds, with results available from 10 of those FECRTs (9 herds). AR to a single ML anthelmintic was detected in all 9 herds, with resistance to Cooperia and Haemonchus spp on 9 farms, and resistance to Ostertagia and Trichostrongylus spp on 2 farms. In contrast, for the ML combination anthelmintics, all FECRTs resulted in efficacies of 99%–100%. The results suggest that cattle producers should strongly consider using combination drenches in their herds in preference to single actives.     

Assessment of diagnostics and antimicrobial susceptibility testing of Brachyspira species using a ring test

There is no ring test for quality assessment available in Europe for diagnostics and antimicrobial susceptibility testing of the fastidious, anaerobic bacteria of the genus Brachyspira. Therefore, an international ring test for Brachyspira spp. was performed once a year during 2002-2004. Two sets of coded samples were prepared and distributed on each occasion. One set comprised six swabs dipped in pig faeces spiked with Brachyspira spp. intended for diagnostics. The other set comprised two pure strains intended only for susceptibility testing. All methods used were in-house methods. The species used were Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira innocens, Brachyspira murdochii and Brachyspira intermedia. In most cases, the correct Brachyspira spp. were detected. However, the results showed that Brachyspira spp. could be difficult to identify, especially if two Brachyspira spp. were mixed or if the concentration of Brachyspira in faeces was low. Additionally, some laboratories reported Brachyspira growth in control samples that were not seeded with any spirochaetes. The lowest detection level was 10(2) bacteria/ml faeces for both B. hyodysenteriae and B. pilosicoli. The susceptibility tests performed showed that disc diffusion was not recommendable for Brachyspira spp. Extended antimicrobial dilution series gave most congruent results. The diversity of the results highlights the importance of ring tests for a high quality of diagnostics and antimicrobial susceptibility tests for Brachyspira spp. This is the first ring test described for Brachyspira spp.     

Visual ecology of the Australian lungfish (Neoceratodus forsteri)

Background

The transition from water to land was a key event in the evolution of vertebrates that occurred over a period of 15–20 million years towards the end of the Devonian. Tetrapods, including all land-living vertebrates, are thought to have evolved from lobe-finned (sarcopterygian) fish that developed adaptations for an amphibious existence. However, while many of the biomechanical and physiological modifications necessary to achieve this feat have been studied in detail, little is known about the sensory adaptations accompanying this transition. In this study, we investigated the visual system and visual ecology of the Australian lungfish Neoceratodus forsteri, which is the most primitive of all the lungfish and possibly the closest living relative to the ancestors of tetrapods.

Results

Juvenile Neoceratodus have five spectrally distinct retinal visual pigments. A single type of rod photoreceptor contains a visual pigment with a wavelength of maximum absorbance (λ_max) at 540 nm. Four spectrally distinct single cone photoreceptors contain visual pigments with λ_max at 366 (UVS), 479 (SWS), 558 (MWS) and 623 nm (LWS). No double cones were found. Adult lungfish do not possess UVS cones and, unlike juveniles, have ocular media that prevent ultraviolet light from reaching the retina. Yellow ellipsoidal/paraboloidal pigments in the MWS cones and red oil droplets in the LWS cones narrow the spectral sensitivity functions of these photoreceptors and shift their peak sensitivity to 584 nm and 656 nm, respectively. Modelling of the effects of these intracellular spectral filters on the photoreceptor colour space of Neoceratodus suggests that they enhance their ability to discriminate objects, such as plants and other lungfishes, on the basis of colour.

Conclusion

The presence of a complex colour vision system based on multiple cone types and intracellular spectral filters in lungfishes suggests that many of the ocular characteristics seen in terrestrial or secondarily aquatic vertebrates, such as birds and turtles, may have evolved in shallow water prior to the transition onto land. Moreover, the benefits of spectral filters for colour discrimination apply equally to purely aquatic species as well as semi-aquatic and terrestrial animals. The visual system of the Australian lungfish resembles that of terrestrial vertebrates far more closely than that of other sarcopterygian fish. This supports the idea that lungfishes, and not the coelacanth, are the closest living relatives of the ancestors of tetrapods.     

Effect of low storage temperature on some of the flavour precursors in garlic (Allium sativum)

Garlic (Allium sativum) cloves were stored at ambient temperature and 4 degrees C for periods up to six months to establish the effect of position of the individual clove within the bulb and of low storage temperature on the composition of several flavours precursors and other organic sulphur compounds, measured by gradient High Pressure Liquid Chromatography. Levels of alliin, gamma glutamyl allyl cysteine sulphoxide and gamma glutamyl isoallyl cysteine sulphoxide were statistically significantly higher in outer than in inner cloves. There was no statistically significant change in levels of alliin, the major flavour precursor, in cloves stored at 4 degrees C, remaining in the average range 17.5+/-3.8-39.1+/-7.5 mM. However, isoalliin increased significantly during storage at 4 degrees C, rising from an average 0.6+/-0.2 mM (outer cloves) -- 0.7+/-0.4 mM (inner cloves) to 7.1+/-1.7 mM (outer cloves) -- 4.1+/-0.7 mM (inner cloves). A decline in other sulphur-containing compounds, most likely to be the peptides gamma-glutamyl allylcysteine sulphoxide and gamma-glutamyl isoallylcysteine sulphoxide, occurred at the same time and possibly contributed to the increase in the flavour precursor compounds. The degree of chemical changes during storage will be of interest to the food and pharmaceutical industries.     

Hatch timing of two subarctic salmonids in a stream network estimated by otolith increments

Hatch timing in autumn-spawning stream salmonids is poorly understood in the subarctic region because snow cover prevents direct sampling of cryptic early life stages. Otolith micro-increment analysis was used to infer hatch dates of white-spotted charr Salvelinus leucomaenis (Pallas) and masu salmon Oncorhynchus masou (Brevoort) in a mainstem-tributary network in northern Japan. Accuracy and precision were validated by ageing hatchery individuals with known hatch date ranges. In July 2018, 93 wild young-of-the-year white-spotted charr and 81 masu salmon were collected and aged. Masu salmon hatched, on average, 24 days earlier (mean = February 8) than white-spotted charr (March 4), and hatch dates spanned a minimum of 2 months for each species. In masu salmon, hatch dates of individuals collected in the mainstem were nearly 3 weeks earlier than those in a tributary. This study provided knowledge on intra- and inter-specific variation in hatch timing of native salmonids in a subarctic stream network.     

Differential responses of body shape to local and reach scale stream flow in two freshwater fish species

Stream flow is recognised as an important influence on the physical traits, distribution and diversity of stream fishes. However, measures of ‘stream flow’ are not consistent among studies and can refer to variables characterising microhabitat (e.g. flow velocity) or reach‐level (e.g. discharge) parameters. Because of the ambiguity associated with the term ‘stream flow’, the differential effect of these two aspects of local stream hydrology on freshwater fishes is unclear. Using two frequently sympatric freshwater fish species, Etheostoma nigrum and Pimephales notatus, we tested for correlations between population‐level body shape and two measures of stream flow, microhabitat flow velocity (m/s) and reach‐level discharge (m³·s^?1). Etheostoma nigrum body shape was correlated with flow velocity, while P. notatus body shape was correlated with mean annual discharge. The respective correlations are potentially manifestations of behavioural differences among the two species. Etheostoma nigrum is a benthic specialist rarely venturing far from its associated microhabitats. Pimephales notatus is a habitat generalist and uses many different microhabitats but is unable to escape the overall discharge pressures of a particular stream. These results demonstrate the importance of considering the spatial scale of variables when predicting phenotype–environment associations.