Reproductive cycles

The nonvisual or subtle effects of air pollutants involve reduced plant growth and alteration of physiological and biochemical processes, as well as changes in the reproductive cycle. Reduction in crop yield can occur without the presence of visible symptoms. This type of injury is often related to low-level, long-term chronic exposure to air pollution. Studies have shown that field plantings exposed to filtered and unfiltered ambient air have produced different yields when no visible symptoms were present (5). Reduction in total biomass can lead to economic loss for forage crops or hay. 

Laboratory studies have also investigated the interaction of air pollutants and the reproductive cycle of certain plants. Subtle changes in reproduction in a few susceptible species can render them unable to survive and prosper in a given ecosystem. 

Forest systems also act as sources of CO2 when controlled or uncontrolled burning and decay of litter occur. In addition, release of ethylene occurs during the flowering of various species. One additional form of emission to the atmosphere is the release of pollen grains. Pollen is essential to the reproductive cycle of most forest systems but becomes a human health hazard for individuals susceptible to hay fever. The contribution of sulfur from forests in the form of dimethyl sulfide is considered to be about 10-25% of the total amount released by soils and vegetation (12). 

The interactions in the intermediate-dose category may result in effects on the reproduction cycle of species, the utilization of nutrients, the production of biomass, and the susceptibility to disease,... 

Using this looser criterion of self-reproduction - it is looser since, unlike von Neumann s requirement, it does not force the self-reproducing structure to be capable of universal construction - Langton discovered a relatively simple self-reproducing structure embedded within a two-dimensional CA that we will refer to as Langton s Loop figure 11.4 shows a few snapshots of its 151 time-step reproduction cycle. 

The gonadotropins (FSH and LH) influence the secretion of sex hormones, development of secondary sex characteristics, and the reproductive cycle in both men and... 

Neurons within the SCN innervate those hypothalamic areas which have a crucial role in the regulation of the reproductive cycle, mood and sleep/arousal, as well as regions such as the basal forebrain and the thalamus which help to determine the state of arousal. They also project to the pineal gland to govern the synthesis and release of... 

Figure 22.1 Pathways projecting to and from the suprachiasmatic nucleus (SCN). Inputs from photoreceptors in the retina help to reset the circadian clock in response to changes in the light cycle. Other inputs derive from the lateral geniculate complex and the serotonergic, Raphe nuclei and help to reset the SCN in response to non-photic stimuli. Neurons in the SCN project to the hypothalamus, which has a key role in the regulation of the reproductive cycle, mood and the sleep-waking cycle. These neurons also project to the pineal gland which shows rhythmic changes in the rate of synthesis and release of the hormone, melatonin...

OBST J M, SEAMARK R F (1975) Hormone Studies on Ewes Grazing an Oestrogenic (Yarloop Clover) Pasture During the Reproductive Cycle. Aust J Biol Sci. 28 279-90. 

Evans C.S. and Goy R.W. (1968). Social behaviour and reproductive cycles in captive Ring-tailed lemurs, Lemur catta. J Zool 156, 171-197. 

Human data divided into specific problems that occur during the reproductive cycle in which caffeine might be implicated. 

OCPs paralyze the nerves of fish, which leads to disruptions in coordination and in the feeding reflex this in turn causes the fish to become emaciated. OCPs also disrupt the metabolizing of carbohydrates, proteins and lipids, and affect the reproductive cycle. All of these factors lead to many fish species weakening and dying out [6]. 

Figure 11.B1 Changes in plasma FSH (a) and LH (b) levels during the reproductive cycle of a healthy human female...

Change in biodiversity Measures of impacts on flora and fauna, e.g. compatibility with native biomass, alteration of production and growth period and geographic distribution of populations and alterations in reproduction cycles of species... 

Hosken, D.J., Blackberry, M.A. Stewart, T.G. and Stucki, A.F. (1998) The male reproductive cycle of three species of Australien vespertilionid bats. J. Zool. Lond. 245, 261-270. 

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