Multifunctionalised benzoxazinones in the systems Oryza sativa–Echinochloa crus‐galli and Triticum aestivum–Avena fatua as natural‐product‐based herbicide leads

BACKGROUND: Fifteen novel derivatives of D‐DIBOA, including aromatic ring modifications and the addition of side chains in positions C‐2 and N‐4, had previously been synthesised and their phytotoxicity on standard target species (STS) evaluated. This strategy combined steric, electronic, solubility and lipophilicity requirements to achieve the maximum phytotoxic activity. An evaluation of the bioactivity of these compounds on the systems Oryza sativa–Echinochloa crus‐galli and Triticum aestivum–Avena fatua is reported here. RESULTS: All compounds showed inhibition profiles on the two species Echinochloa crus‐galli (L.) Beauv. and Avena fatua L. The most marked effects were caused by 6F‐4Pr‐D‐DIBOA, 6F‐4Val‐D‐DIBOA, 6Cl‐4Pr‐D‐DIBOA and 6Cl‐4Val‐D‐DIBOA. The IC₅₀ values for the systems Echinochloa crus‐galli–Oryza sativa and Avena fatua–Triticum aestivum for all compounds were compared. The compound that showed the greatest selectivity for the system Echinochloa crus‐galli–Oryza sativa was 8Cl‐4Pr‐D‐DIBOA, which was 15 times more selective than the commercial herbicide propanil (Cotanil‐35). With regard to the system Avena fatua–Triticum aestivum, the compounds that showed the highest selectivities were 8Cl‐4Val‐D‐DIBOA and 6F‐4Pr‐D‐DIBOA. The results obtained for 6F‐4Pr‐D‐DIBOA are of great interest because of the high phytotoxicity to Avena fatua (IC₅₀ = 6 µM , r² = 0.9616). CONCLUSION: The in vitro phytotoxicity profiles and selectivities shown by the compounds described here make them candidates for higher‐level studies. 8Cl‐4Pr‐D‐DIBOA for the system Echinochloa crus‐galli‐Oryza sativa and 6F‐4Pr‐D‐DIBOA for Avena fatua‐Triticum aestivum were the most interesting compounds. Copyright © 2010 Society of Chemical Industry     

A lower motor neuron disease in newborn Romney lambs

AIM: To determine the cause and nature of a disease in newborn New Zealand Romney lambs characterised by progressive weakness and premature death. METHODS: Affected lambs were examined clinically, humanely killed and submitted to necropsy. Selected fonmalin-fixed tissues were examined histologically. Data on the parentage of the lambs were collected. RESULTS: The principle lesions found were degeneration and loss of neurons in ventral horns of the spinal cord and brain stem and Wallerian degeneration of motor nerves and denervation atrophy of skeletal muscles fibres. CONCLUSION: The lesions are those of a lower motor neuron disease which appeared to have a genetic cause.     

Cilia-associated respiratory bacillus infection in rats in New Zealand

AIMS: To demonstrate cilia-associated respiratory (CAR) bacillus associated with chronic pneumonia in wild and pet rats in New Zealand. METHODS: A range of tissues from 4 rats were examined grossly and by light microscopy and affected lungs were examined by transmission electron microscopy. RESULTS: All 4 rats had moderate to severe cranioventral bronchopneumonia with bronchiectasis and large numbers of argentophilic bacteria resembling CAR bacillus, intimately associated with the bronchial epithelium. CONCLUSIONS: CAR bacillus infection should be considered as a differential diagnosis for pneumonia in rats in New Zealand.     

Insect midgut structures and molecules as targets of plant‐derived protease inhibitors and lectins

The midgut of insects is involved in digestion, osmoregulation and immunity. Although several defensive strategies are present in this organ, its organization and function may be disturbed by some insecticidal agents, including bioactive proteins like lectins and protease inhibitors (PIs) from plants. PIs interfere with digestion, leading to poor nutrient absorption and decreasing amino acid bioavailability. Intake of PIs can delay development, cause deformities and reduce fertility. Ingestion of PIs may lead to changes in the set of proteases secreted in the insect gut, but this response is often insufficient and results in aggravation of the malnutrition status. Lectins are proteins that are able to interact with glycoconjugates, including those linked to cell surfaces. Their effects on the midgut include disruption of the peritrophic matrix, brush border and secretory cell layer; induction of apoptosis and oxidative stress; interference with nutrient absorption and transport proteins; and damaging effects on symbionts. In addition, lectins can cross the intestinal barrier and reach the hemolymph. The establishment of resistant insect populations due to selective pressure resulting from massive use of a bioactive protein is an actual possibility, but this can be minimized by the multiple mode‐of‐action of these proteins, mainly the lectins. © 2018 Society of Chemical Industry     

Recent advances in allelopathy for weed control: from knowledge to applications

Allelopathy is the biological phenomenon of chemical interactions between living organisms in the ecosystem, and must be taken into account in addressing pest and weed problems in future sustainable agriculture. Allelopathy is a multidisciplinary science, but in some cases, aspects of its chemistry are overlooked, despite the need for a deep knowledge of the chemical structural characteristics of allelochemicals to facilitate the design of new herbicides. This review is focused on the most important advances in allelopathy, paying particular attention to the design and development of phenolic compounds, terpenoids and alkaloids as herbicides. The isolation of allelochemicals is mainly addressed, but other aspects such as the analysis and activities of derivatives or analogs are also covered. Furthermore, the use of allelopathy in the fight against parasitic plants is included. The past 12 years have been a prolific period for publications on allelopathy. This critical review discusses future research areas in this field and the state of the art is analyzed from the chemist's perspective. © 2019 Society of Chemical Industry     

The effect of light intensity on growth of juvenile dusky kob Argyrosomus japonicus (Temminck & Schlegel 1843)

South African juvenile dusky kob Argyrosomus japonicus are more abundant in turbid estuaries than in clear marine‐dominated estuaries. Turbidity can reduce light penetration into the water and create an environment different from that experienced by fish under culture conditions in mechanically filtered clear water. In order to optimize rearing conditions of this species, the effects of light intensity (23–315 lx) and feeding method (restricted ration vs. feeding to apparent satiation) on growth and food conversion ratio (FCR) of juvenile A. japonicus were assessed in a 56‐day growth trial. Fish weight increased from 7.2±1.6 to 41.9±10.2 g fish^?1 at a growth rate of 3.25% body weight day^?1. Light intensity did not significantly affect growth or FCR. Feeding method did not significantly affect growth rate, but average FCR was significantly better in treatments fed a ration of 3.6% body weight day^?1 than in treatments fed to apparent satiation. Therefore, a light intensity range of 23–315 lx can be used to culture dusky kob juveniles. The better FCR in fish fed a restricted ration suggests that a ration of 3.6% body mass day^?1 allowed good growth of juvenile dusky kob.     

Influence of the Freezing Technique (Nitrogen Liquid vs Ultrafreezer of −152°C) and Male-to-Male Variation Over the Semen Quality in Canarian Mastiff Breed Dogs

This study was carried out to assess the in vitro quality of canine semen frozen in an ultrafreezer at -152 degrees C and to evaluate the male-to-male variation of frozen semen in five male dogs of the Canarian Mastiff breed. Four ejaculates of each dog were processed individually (5% glycerol and 0.5% Equex) to reach a final concentration of 100 x 10(6) spermatozoa/ml. Then, two freezing techniques were tested to assess the seminal quality (sperm motility, live spermatozoa and abnormal sperm cell percentages) at 1, 30, 60, 120 and 360 days after freezing: (i) semen was frozen and stored in liquid nitrogen; (ii) semen was frozen and stored in the ultrafreezer at -152 degrees C. After freezing-thawing, both freezing protocols showed no significant differences in sperm motility and the percentages of live and abnormal spermatozoa. On the other hand, the microscopic characteristics of spermatozoa in fresh semen were practically similar among males; however, after the semen processing and freezing, significant differences were observed (p < 0.05) among males, especially as regards sperm motility. This inter-individual variability was detected in both freezing protocols, showing that the male-to-male variation in the seminal quality post-freezing was independent of the freezing technique used. The in vitro results obtained in the Canarian Mastiff breed confirmed that the use of ultra-freezers at -152 degrees C is a potential alternative to liquid nitrogen for storing canine semen for long periods of time.     

Luteal Characteristics and Progesterone Production on Day 5 of the Bovine Oestrous Cycle

In this study we have examined luteal function in non-lactating and late lactation dairy cows on day 5 of the cycle, during the period of the post-ovulatory progesterone rise. Comparison of luteal progesterone content and in vitro synthetic capacity with circulating plasma progesterone demonstrated that circulating progesterone concentration is a function of total luteal activity rather than the activity of individual units of tissue. Incubation of luteal tissue in vitro demonstrated stimulatory activity of LH and IGF-I, and to a greater degree IGF-II, on luteal progesterone synthesis. Finally the study showed no effect of double ovulation on luteal function. Occurrence of double ovulation in 35% of animals was not associated with any difference in luteal function or plasma progesterone concentrations.     

Suspected zinc-induced copper deficiency in growing kittens exposed to galvanised iron

AIM: To investigate the possible causes of fading coat colour and an acquired hind-limb ataxia affecting sixteen 4 to 5-month old kittens in a closed feline colony during 1993 and 1994. METHODS: Records of kittens and litters born in the colony between 1991 and 1997 were analysed. The kittens had been kept from birth until approximately 5 months of age in plastic cages with galvanised iron bar doors. Histopathological sections from 4 of the worst affected ataxic kittens necropsied in 1993 were re-examined. In addition, 6 of the original 16 affected kittens that survived were re-examined as 4 to 5-year old adults, which were moderately ataxic; these cats were then humanely killed for necropsy. RESULTS: In the kittens, clinical signs included lordosis, dysmetria, ataxia of the hind-limbs and fading coat colour; histopathological lesions included Wallerian-type degeneration in the spinal cord, pons and medulla, and neuronal degeneration in the vestibular nuclei and ventral horns of the spinal cord. Analysis of colony data ruled out an inherited disease, and there was no evidence of dietary inadequacy or excess. Similar, though milder, clinical and histopathological changes were noted in the affected adults. CONCLUSIONS: Circumstantial evidence is consistent with a diagnosis of zinc-induced copper deficiency caused by the ingestion of zinc oxide from the galvanised iron bar doors. CLINICAL RELEVANCE: Because of the possibility of zinc-induced copper deficiency, galvanised iron should be avoided when designing and constructing cages for cats in veterinary clinics, pet shops and boarding facilities.